COMPARATIVE ANALYSIS OF STOMATAL CHARACTERS IN TWO PHENOTYPES WIDELY DIFFERENTIATED IN A POPULATION OF LOTUS GLABER MILL . [SYN. L. TENUIS WALDST. ET KIT(FABACEAE)]
Materials and methods
Results and discussion
Table 1 indicates that were found significant differences (t test, P < 0,01) among DP and TP for the characters: stomata density on UE and LE, length of the stomata in UE and the ratio width /length of the stomata in UE.
The stomata density and the stomata size found in both epidermal surfaces of TP was very approaching to those that had been communicated by Arambarri and Colares (1993). The DP showed lower stomata density on both epidermis and stomata on UE longer than the TP plant. This «dilution» of stomata density of DP has been apparently balanced by the increasing size, in length of individual stomata, but it was only on the upper epidermis. In addition to this, similar changes in stomata characters has been associated with a increase in the ploidy level (Willmer, 1983).
The variation coefficient indicated that was a wide variation among the analyzed samples for the stomata density on UE and LE surfaces, especially in the case of DP. By the contrary, the coefficient of variation was low for the width and length of the stomata, especially in the case of DP. These results point out that the stomata size was more constant character than stomata density and that this pattern to become more accentuated in DP than TP.
On the other hand, the stomata density ratio UE /LE, the Table 2 shows that the analysis based on random combinations UE-LE density data denote significant differences among DP and TP (test of «t», P < 0,01). In L. glaber has been determined that the leaves present greater stomatal number in the upper epidermis (Arambarri and Colares, 1993). This sort of distribution adaxial/abaxial of stomata was confirmed in this experience and more over it was found that in the «new» (DP) phenotype was significantly more remarkable (Table 2). Stomata distribution on adaxial/abaxial epidermis was related with the loss of water from leaves that is greater from the stomata of adaxial surface (Robins et al , 1965). According this interpretation the DP plants presents a ratio that would be favorable to a greater loss of water than TP plants.
It was determined by the analysis of single correlation that in TP the analyzed characters varied in independent form (P > 0,05), while in DP only was significant the correlation width vs. length of the LE stomata, (r=0,48, P=0,0003).
Results indicate that the phenotype «new» (DP) present differences from the normal (TP) in the stomata density, stomata length on the UE and density ratio UE /LE. The precedents on the origin of the evaluated materials and the uniformity of the environment conditions during their development permit to suppose that the registered differences could be genetics. This will be studied in future experiences.
Acknowledgments
The authors wish to express their appreciation to Prof. Ana María Arambarri, Area de Botánica, for her assistance.
References
Arambarri AM and M Colares, 1993 L. corniculatus L. and L. tenuis Waldst. et Kit (Leguminosae) anatomy of the leaf. Lotus Newsletter, 24: 38-39.
Tichá I, 1985 Ontogeny of leaf morphology and anatomy. In: Photosynthesis during leaf development, De. Zdenek Sestak. 16-50.
Lüttge U., M. Kluge and G. Bauer, 1993. Botánica. McGraw Hill/Interamericana de España, Madrid. 573 pp.
Willmer C M, 1983. Stamata. Longman Group Limited. London. 192 pp.
Robbins WW, TE Weier and CR Stocking, 1965. Transpiration, conduction and absortion. In: Botany. An introduction to plant science. John Wiley & Sons, Inc., third edition. 167-181.
(**): indicated significant differences (t test, P < 0,01), between the means of TP and DP for each character.
(n.s.): differences are not significant.
(**): difference between XTP and XDP is significant (t test, P<0.01)
CHANGES IN THE RELATIVE CONCENTRATIONS OF FLAVONOIDS RELEASED NATURALLY FROM LOTUS GLABER (SYN. L. TENUIS) SEEDS DURING GERMINATION
Wagner M.L.1,2, Kade M.3, Strittmatter C.D.3, Ricco R.A.1 and Gurni A.A.1
1Cátedra de Fármacobotánica
2Museo de Farmacobotánica «Juan A. Domínguez»
Fac. de Farmacia and Bioquímica (UBA)
Junín 956
1113 Buenos Aires. Argentina.
3CEVEG-CONICET
Serrano 669
1414 Buenos Aires. Argentina.
Lotus glaber Mill . (syn. L. tenuis Waldst. et Kit exWilld). is the only important pasture legume for the Flooding Pampa (Depresión del Río Salado), the most extensive region for calf production in Argentina (7.5 million hect.). The species has perfectly adapted to the unfavorable environmental conditions of this area, to such an extent that during spring and summer it is a dominant species in the natural grasslands that cover the region (Collantes et al. 1988).
Our previous studies in birdsfoot trefoil have demonstrated the dependence of flavonoid composition on developmental stage (Strittmatter et al. 1992, 1994; Wagner et al. 1996). Kaempferol and its glycosides were identified during the whole life cycle of the plant in different organs, whereas free quercetin (Q) and its two glycosides could only be detected in the seeds of L. glaber (Strittmatter et al. 1994; Wagner et al. 1996).
In the present study, the identification of seed flavonoid was completed including the isoflavones. Their distribution was examined during germination, as well as in exudates from seeds, in order to evaluate the role of these flavonoids in response to soil bacteria.
Experimental procedures
Results
Discussion
Analysis of the flavonoids released during imbibition and germination of L. glaber seeds confirmed our previous results (Wagner et al. 1996) that Q and its glycosides are the dominant flavonoids in the seeds.
These results agree with Hartwig et al. (1991) and Tsai and Phillips (1991), who detected that nearly half (46%) of the flavonoids fraction released from intact alfalfa seeds consisted of Q or its derivatives.
The presence of an isoflavone in dry seeds of L. glaber is also noteworthy. Bonde et al. (1973) and Ingham (1977) reported the isolation of the two isoflavans sativan and vestitol in leaves of L. corniculatus, a closely related species to L. glaber, but in response to inoculations with fungi. Flavonols and isoflavones released from L. glaber seeds were also identified in dry seeds, and thus, they would not function as phytoalexins; they must have been synthesized previously.
It remains to be determined which seed tissue is the source of the mentioned flavonoids; alfalfa seeds most apparently store the flavonoids in the seed coat (Hartwig and Phillips, 1991), whereas in soybean the amounts of isoflavones were much larger in the cotyledons than in the roots or hypocotyls (Suganuma and Takaki, 1992).
Data from this study suggest the following preliminary model of how flavonoids diffuse from seeds during the initial stages of germination. Seeds release the isoflavone and KSR during imbibition into aqueous solution as well as Q glycosides. The aglycones, which are less soluble in water than glycosides, diffuse away from the already germinating seed as revealed the filter paper (Table 2).
Although it could be questionable to extrapolate directly the results from this experiment to the soil environment, the mentioned flavonoids should certainly affect soil microorganisms.
EFFECTS OF FLOODING ON THE REPRODUCTION OF LOTUS GLABER (SYN. L. TENUIS) AND LOTUS CORNICULATUS
Osvaldo R. Vignolio, Néstor O. Maceira and Osvaldo N. Fernández
Cátedra de Ecología
Unidad Integrada Balcarce FCAUNMdP/EEA-INTA
C.C. 276, 7620 Balcarce, Argentina.
Flooding effects on the reproduction of Lotus glaber Mill . and Lotus corniculatus L. were studied under experimental conditions. The hypothesis that, the effects of flooding on the reproduction differ with species and plant age, was tested.
Flooding were carried out in winter (42 days flooding), spring (49 days) and summer (17 days),in pots under field conditions. Spring flooding was applied to young (133 days) and old (208 days) plants. Winter flooding did not affect weight and number of fruits and seeds per plant. Reproductive characteristics in plants of different age and treatment of the same species were not affected by spring flooding. Lotus glaber produced more fruits and seeds than Lotus corniculatus in the spring flooding.
Indeterminate reproduction and higher reproductive effort of young plants, determined that reproductive traits for each species had no significant differences between treatments and plant age. Summer flooding (17 days) promoted both flower and fruit abortion and a plant mortality of 100 % in L. corniculatus and 50 % in L. glaber.
EFFECTS OF FLOODING ON THE GERMINATION OF LOTUS GLABER (SYN. L. TENUIS) AND LOTUS CORNICULATUS SEEDS. THEIR ROLE IN THE DIFFERENTIAL DISTRIBUTION OF BOTH SPECIES IN THE FLOODING PAMPA (BUENOS AIRES, ARGENTINA).
Lotus glaber (L.g.) and Lotus corniculatus (L.c.) were introduced as forage plants in the Flooding Pampa around 50 years ago. While L.g. has naturally colonized the frequently flooded habitats. L.c. has not shown the same expansion. In this paper we studied the tolerance to flooding of seeds of both species. The seeds were flooded during 7 weeks, in controlled conditions of temperature and light, and samples were taken at increasing time intervals. Germination percentage (G.P.) of the seeds was taken as a measure of tolerance to flooding and it was found that although G.P. decreased with flooding time in both species, the soft seeds of L.c. lost viability earlier than those of L.g. With 49 days of flooding, hard seeds were the only ones that maintained the G.P. and were more frequent in L.g. (approximately 50 % in L.g. and 6 % in L.c., in 5 months old seed). These characteristics probably play an important role in the capacity of L.g. of colonizing habitats that are periodically flooded.
Ecología Austral Vol.5, No 2: 157-163, 1995.
STUDIES ON THE SYMBIOTIC POTENTIAL OF A RHIZOBIUM LOTI STRAIN NATIVE FROM CHASCOMÚS ON LOTUS PEDUNCULATUS AND LOTUS CORNICULATUS VAR . HIRSUTUS PLANTS
M. Julia Estrella, Fernando L. Pieckenstain, Rodolfo A. Ugalde and Alberto A. Iglesias.
Instituto Tecnológico de Chascomús (INTECH — CONICET)
Camino Circunv. Laguna
km 6. Casilla de Correo 164
Chascomús (7130). Bs. As. Argentina.
INTRODUCTION
The Salado River Basin is an extense area in Buenos Aires province (Argentina) dedicated to beef and dairy cattle production, which is mainly sustained on a grazing system based on native grasslands with a minor portion of cultivated pastures. Therefore, proven the extensive conditions of cattle production in the area, nitrogen contents of the forage biomass is a critical point determining yield for the process. Any future intensification in animal production within a pasture based system will demand an increase in the amount and the quality of forage supply. In this way, great amounts of nitrogen should be incorporated to the plant-soil system (Simpson and Stobbs, 1981). Basically, this can be achieved by periodical applications of nitrogen-containing fertilizers or, alternatively, through the symbiotic fixation of atmospheric nitrogen.
Legumes associate in a symbiotic way with bacteria belonging to the genus Rhizobium, thus producing root nodules where the nitrogen fixation process occurs. Recent agronomic studies about Lotus species cultivated in the introduction garden of the Instituto Tecnológico de Chascomús (INTECH), project L. pedunculatus and L. corniculatus var . hirsutus by their good adaptability to local conditions (Remis et al, 1996). The former is a commercial forage and the latter is a non commercial botanical variety. Both of them have still not been tested nor cultivated in the region. Nutritional evaluations done by our group (Locatelli et al., this issue) suggest that this two species might substantially improve the quality of pastures present in the zone by increasing their protein content.
Condensed tannins are known to be present in Lotus species and their compositions usually differ between them (Pankhurst and Jones, 1979; Pankhurst et al., 1987). These compounds could affect nodulation of such legumes and indirectly diminish plant persistence and quality, particularly in low fertile and poorly drained soils. Pankhurst and Jones (1979) found that delphinidin rich tannins accumulated in roots and ineffective nodules of L. pedunculatus. They suggested that such ineffectiveness could be due to the sensitivity of Rhizobium strains located in the nodules to those compounds. L. corniculatus var. hirsutus roots also contain a high level of delphinidin rich tannins, but lower than roots of L. pedunculatus plants. On the contrary, condensed tannins present in L. glaber do not contain delphinidin in their structure (Pankhurst and Jones, 1979; Pankhurst et al., 1987).
R. loti strains commonly found in soils of the Salado River Basin are able to form nodules in L. glaber roots. However, no data concerning the capacity of these strains to nodulate other Lotus species are currently available. The aim of the present work was to determine the ability of an indigenous strain of R. loti isolated from L. glaber to form effective nodules in other Lotus species. Data are compared with two additional strains of R. loti: one of them (NZP 2037) is known to form effective nodules in roots of both Lotus species used in this study, while the other (NZP 2213) forms ineffective nodules on some species which contain delphinidin rich tannins in their roots (e.g. L. pedunculatus) (Pankhurst et al., 1987).
MATERIALS AND METHODS
Plant material and culture: Legumes used in this study were L. corniculatus var . hirsutus and L. pedunculatus. Seeds obtained from the introduction garden were surface disinfected with concentrated sulfuric acid for 15 min, thoroughly rinsed with sterile distilled water and then kept in water for 24h. After that, they were placed in culture tubes containing 20 ml of solid Jensen medium (Vincent, 1970) and incubated in a climatized room at 25°C with a photoperiod of 16 h.
Rhizobium loti strains: Strain 1-INTECh was originally isolated from nodules of L. glaber plants naturally growing in the outskirts of the INTECH. Strains NZP 2037 and NZP 2213 from Beltsville Rhizobium Culture Collection were kindly gifted by Dr. Paul Beuselinck, USDA-ARS, University of Missouri, Columbia, MO, USA. Bacteria were cultured in AMA medium (Vincent, 1970), at 28°C with rotatory shaking.
Nodulation assay: Three days after transfer to culture tubes, seedlings were inoculated with 0.1 ml of bacterial culture and incubated in the above stated conditions for a 6 week period. Combinations of each Lotus species and bacterial strain were done, each one consisting of 24 plants. Control plants were inoculated with the same volume of AMA medium.
Nitrogenase activity determination: Nitrogenase activity of nodules was measured by using the acetylene reduction technique (Hardy et al., 1968) on the same plants used for the nodulation assay. Six weeks old plants were placed in 50 ml culture tubes (8 plants each) and hermetically closed with rubber caps. Each treatment included three replicate tubes. Air (5 ml) was withdrawn and replaced by an equivalent volume of acetylene. Tubes were incubated at 25°C during 2 h, and then 0.5 ml gas samples were removed and analysed for acetylene and ethylene content using a Hewlett-Packard 5890-A gas chromatograph fitted with a flame ionization detector and «Poropak N» in a 1.5 mm x 1.32 m column.
RESULTS
Figure 1 shows whole plants of L. pedunculatus (Fig. 1A) and L. corniculatus var . hirsutus (Fig. 1B) inoculated with three different strains of R. loti: the two collection strains NZP 2213 and NZP 2037, and the indigenous strain 1-INTECh. L. pedunculatus plants inoculated with strains NZP 2213 and 1-INTECh had a morphological aspect similar to that of non-inoculated plants (Fig. 1A). Their aerial parts were scarcely developed and exhibited chlorotic leaves. On the contrary, L. pedunculatus plants inoculated with strain NZP 2037 showed a normal development of aerial parts and no symptoms of chlorosis were detected on leaves. On the other hand, L. corniculatus var . hirsutus plants inoculated with all three strains grew more vigorously than controls (Fig. 1B), although some chlorosis was observed in leaves of plants inoculated with strain 1-INTECh. Nodules formed by strain NZP 2037 in both Lotus species looked similar . They were spherical and pink coloured. Strains NZP 2213 and 1-INTECh also formed this type of nodules in L. corniculatus var hirsutus plants but in L. pedunculatus plants they formed pseudonodules.
Figure 1: Nodulation of plantlets of L. pedunculatus (A) and L. corniculatus var hirsutus (B) by Rhizobium strains (from left to right : control, 1-INTECh, NZP 2213 and NZP 2037).
Table 1 shows results obtained when nitrogenase activity was measured in nodules of Lotus plants inoculated with the three different R. loti strains. As shown, strain NZP 2037 was capable of forming effective, nitrogen-fixing (Nod+ fix+) nodules with the two species of Lotus. Strain NZP 2213 formed (Nod+ Fix+) nodules in L. corniculatus var . hirsutus and ineffective (Nod+ Fix-) nodules in L. pedunculatus. Indigenous strain 1-INTECh formed (Nod+ Fix-) nodules in both species, even when the morphology of those formed in L. corniculatus var . hirsutus was very similar to that of effective ones.
REFERENCES.
Hardy, R.W.F.; R.D. Holsten; E.K. Jackson and R.C. Burns (1988) Plant Physiol. 43: 1185-1207.
Pankhurst, C.E. and W.T. Jones (1979) J. Exp. Bot. 30: 1109-1118.
Pankhurst, C.E.; D.H. Hopcroft and W.T. Jones (1987) Can. J. Bot. 65: 2676-2685
Remis, J.L.; O.A.Ruiz; R.A.Ugalde and A.A.Iglesias (1995) Lotus Newsletter 26:17-20
Simpson, J.R. and T.H. Stobbs (1981) In: Grazing Animals (Morley, F.W., ed.). pp. 261-287. Elsevier Scientific Publishing Company, Melbourne.
Vincent, J.M. (1970) A Manual for the Practical Study of Root Nodule Bacteria. Blackwell Scientific Publications, Oxford.
EVALUATION OF FORAGE QUALITY ATTRIBUTES FOR LOTUS SPP. GROWN IN THE SALADO RIVER BASIN
M. Laura Locatelli, José L. Remis and Alberto A. Iglesias.
Instituto Tecnológico de Chascomús (INTECH — CONICET)
Camino Circunv. Laguna
km 6. Casilla de Correo 164
Chascomús (7130). Bs. As. Argentina.
INTRODUCTION
Beef and dairy cattle production in the Salado River Basin is essentially a grazing system mainly based on natural grasslands, with a minor portion of cultivated pastures. Edaphic characteristics: limed and poorly drained soils with severe phosphorus deficiency, medium organic matter levels, high alkalinity and salinity; together with periodic exposition of soils to waterlogged conditions, significantly decrease persistence and yield of common legume species (red clover, alfalfa, white clover) in this region (Mazzanti et al., 1986). A strategy to be developed to solve these problems is the introduction of foreign legume species. In this way, Lotus spp. is an important alternative, after their growing conditions and significant nutritional value. Currently, the genus Lotus has been introduced in the Salado River Basin which counts with L. corniculatus and L. glaber (already naturalized) species. However, at the present time, information about nutritional quality (and its variability throughout the year) of commercial species in the area is scarce, and an exhaustive analysis on the productive performance of Lotus in the region is far from complete.
In grazing systems (preferentially extensive) animal production will be highly influenced by nutritional variability of forage offer along the year. Therefore, it is relevant to know (besides biomass production) the nutritional attributes (protein, energy, etc.) and the efficiency by which ruminants profit different legume forage species. After this information, it is possible to design different utilization and agronomic management strategies to obtain a maximum yield from a specific forage material. It has been reported (McGraw et al., 1989) the relevance of an early evaluation of quality parameters in introduction trials of unknown species, in order to identify desirable or undesirable characteristics and thus to postulate rationale strategies for the improvement of forage quality.
Last year, we reported studies carried out at Instituto Tecnológico de Chascomús (INTECH) concerning green and dry matter production for different Lotus spp. growing at an introduction garden located in the Salado River Basin region (Remis et al., 1995). The present study completes that previous evaluation by analysis of chemical and biological parameters determining the quality of the different plant species.
MATERIALS AND METHODS
Aerial biomass (whole plant) of the different Lotus entries (perennial species) was sampled from small plots of the introduction garden during years 1994 and 1995. According to seasonal periods and plant species, these samples included leaves, stems, flowers and/or fruits. Distribution in the different seasonal periods was made by considering the time of sample collection as follows: i) Fall-winter: from late March to early August, ii) Spring: from mid October to mid November, and iii) Summer: from late December to mid February. Samples were oven-dried at 60°C until constant weight to determinate dry matter (DM) content (data expressed as % of the aerial biomass), and then milled to 1 mm by using a Wiley-type mill.
Crude protein (CP) was estimated in the samples by total nitrogen determination after sulfuric acid digestion, distillation and titration by the Kjeldahl method (N x 6.25). Neutral detergent fiber (NDF) was determined according to Goering and Van Soest (1970). The enzymatic pepsin-cellulase method (Donofer et al., 1963) was use to measure DM in vitro digestibility (DMIVD) of the samples. CP, NDF and DMIVD are expressed as % of the DM.
RESULTS AND DISCUSSION
Table 1 shows quality parameters determined for periods of spring and summer in different Lotus spp. grown at the introduction garden in INTECH. Data corresponding to Medicago sativa and Trifolium pratense are included to establish a comparison with two commonly used forage species. As shown (Table 1) besides L. glaber and L. corniculatus (the two commercial species already used in the region) other forage materials exhibited relatively low NDF levels, as well as CP and DMIVD values higher than the mean found for the different Lotus spp. analyzed. In this way, L. corniculatus var . hirsutus showed a good pattern of quality parameters, thus reinforcing the promising data previously obtained with this species (Remis et al., 1995). Table 1 also shows that the hybrid L. corniculatus x L. pedunculatus exhibited high values of CP and DMIVD during the spring, whereas similar results are observed for L. parviflorus during the summer peirod. Concerning L. rectus, Table 1 shows that this species exhibited low parameter values estimating quality. However, it needs to be considered that L. rectus was the only arbustive species in the introduction garden, and that the data could be masked by a significant proportion of lignified stems in the samples. Periodic defoliations of aerial biomass could reverse the low leaf to stem ratio found in our samples and renders a more actual picture of the nutritive value of L. rectus when utilized by ruminants.
ACKNOWLEDGMENTS
The authors are greatly indebted to D.F. Gómez Casati and G.A. Polenta for helpful suggestions on the experimental procedures. AAI is a Member of the Investigator Career from CONICET.
REFERENCES
Barry, T.N., Manley, T.R. and Duncan, S.J. 1986. The role of condensed tannins in the nutritional value of Lotus pedunculatus for sheep. 4. Sites of carbohydrates and protein digestion as influenced by dietary reactive tannin concentration. British J. Nutr. 55:123-137.
Carámbula, M., Ayala, W. and Carriquiry, E. 1994. Lotus pedunculatus. Adelantos sobre una forrajera que promete. Serie Técnica Nº 45. INIA, Uruguay.
Chiquette, J., Cheng, K.J., Rode, L.M. and Milligan, L.P. 1989. Effect of tannin content in the two isosynthetic strains of birdsfoot trefoil ( Lotus corniculatus L.) on feed, digestibility and rumen fluid composition in sheep. Can. J. Anim. Sci. 69:1031-1039.
Donefer, E. Niemann, P.J., Crampton, E.W. and Lloyd, L.E. 1963. Dry matter disappearance by enzyme and aqueous solutions to predict the nutritive value of forages. J. Dairy Sci. 46:965-970.
Forde, M.B. and de Latour, G. 1978. Plant introduction trials. Classification of Lotus introductions. N.Z. J. Exptl. Agr. 6:293-7.
Goering, H.K. and Van Soest, P.J. 1970. Forage fiber analysis (apparatus, reagents, procedures and some applications). Agric. Handbook 379. USDA.
Kelman, W.M. and Tanner, G.J. 1990. Foliar condensed tannin levels in Lotus species growing on limed and unlimed soils in South-Eastern Australia. Proc. N.Z. Grassl. Assoc. 52:51-54.
Lowther, W.L., Manley, T.R. and Barry, T.N. 1987. Condensed tannin concentrations in Lotus pedunculatus cultivars grown under low soil fertility conditions. N.Z. J. Agric. Res. 30:23-25.
Mazzanti, A., Darwich, N.A., Cheppi, C. and Sarlangue, H. 1986. Persistencia de pasturas cultivadas en zonas ganaderas de la Pcia. de Buenos Aires. Rev. Arg. Prod. Anim. 6 (Sup. 1):65.
McGraw, R.L., Beuselinck, P.R. and Marten, G.C. 1989. Agronomic and forage quality attributes of diverse entries of birdsfoot trefoil. Crop Sci. 29:1160-1164.
Remis, J.L., Ruíz, O.A., Ugalde, R.A. and Iglesias, A.A. 1995. Evaluation of Lotus spp. growth in the Salado River Basin. Lotus Newslett. 26:17-20.
Roberts, C.A. and Beuselinck, P.R. 1992. Condensed tannins in Lotus species. Lotus Newslett. 23:41.
Waghorn, G.C., Shelton, I.D. and McNabb, W.C. 1994. Effects of condensed tannins in Lotus pedunculatus on its nutritive value for sheep. 1. Non-nitrogenous aspects. J. Agric. Sci. 123:99-107.
After the seedling emergence it was observed a notorius alteration in the uniformity size of the seedlings aerial part. Among the fourth and fifth weeks the seedlings were removed from the tray and it were evaluated the roots and the aerial components.
The seedling abnormalities observed were: The roots of the most seedlings showed some alterations in their morphology and size, inhibition of roots elongation coupled with lateral swelling , hypertrophyes, be bent into curls and a negative gravitropism in lateral roots. The more important seedling abnormalities are shown in the figure 1 (a). Seedlings with their roots affected and also normal seedlings were registered, (n=114). The frequency of seedlings affected and unaffected was 73.68% and 26.32%, respectively.
Figure 1. (a) Seedling abnormalities: small size of aerial part, hypertrophyes and curls in the root system. (b) Recovery of the abnormal seedlings after fourth weeks cultivated at the open air.
The abnormal plants were cultivated during fourth weeks at the open air in pots with agricultural ground to evaluate their following behavior. During the fourth weeks that the plants were cultivated in the open air it was register that the affected plants were recovering gradually their normal growth. Immediately to the end of this period was observed that, from the affected roots had been originated roots with normal morphology (figure 1 ( b)).
REFERENCES
Abeles FB, PW Morgan and ME Saltveit Jr (1992) Ethylene plant biology. Academic Press Inc.. New York. 414 pp.
NEW MORPHOLOGICAL PHASES DELIMIT LOTUS STRIGOSUS (NUTTALL) GREENE VAR. TOMENTELLUS ISELY FROM LOWER CALIFORNIA AND SONORA, MEXICO (FABACEAE — LOTEAE)
Ana M. Arambarri
Area de Botánica, Jardín Botánico y Arboretum «C. Spegazzini»
Facultad de Cs. Agrarias y Ftales — UNLP
C. C. 31, 1900 La Plata, Argentina
Abstract. The Lotus strigosus var. tomentellus complex from Lower California and Sonora, Mexico in which «phases» to denote aberrant forms or intermediates within a species have been found was studied morphologically. Until present the phases 1 and 2 are knowledge for L. strigosus var . tomentellus Isely. The specimens of herbarium (MEXU) were examined with a stereoscopic microscope and the topographic features of the testa were analyzed by SEM. According to morphological characteristics found the specimens studied were separated in three groups. The group 1 correspond to L. strigosus var. tomentellus «phase 1» Isely. It is characterized by the presence of peduncled inflorescence with flowers more than 7 mm length, and the bract 1-2 (-3) leaflets. The groups 2 and 3 agree with L. strigosus var . tomentellus Isely by the presence of flowers no more than 6 mm length, subsessiles or shortly peduncled and bract absent. However, fruit and seed characteristics delimit two new morphological phases to L. strigosus var . tomentellus from Lower California and Sonora, Mexico. They are «phase 3» to group 2 with fruit incurved, falcate, and seed with the hilum superficial, and «phase 4» to group 3 with fruit distally incurved and seed with the hilum sunken in a lateral notch.
Key words: Fabaceae; Loteae; Lotus; Lower California; Mexico; morphology; phases; Sonora.
Introduction
Isely (1981) uses the word «phases» to denote aberrant forms or intermediates within a species. Such «phases» have been found in this study in the L. strigosus var . tomentellus complex from Lower California and Sonora, Mexico.
Lotus strigosus (Nutt.) Greene, L. strigosus var. hirtellus (Greene) Ottley and L. strigosus var . tomentellus (Greene) Isely are distributed in California, Lower California, and Mexico.
The Lotus strigosus group shows a continuous variation in its morphological characteristics. According to Isely (1981), Nuttall's (1838) names Hosackia nudiflora, H. rubella and H. strigosa illustrate local population variance. Greene (1890) examined and subdivided Nuttall's species in the L. strigosus group. He renamed L. tomentellus to one species from Lower California.
Later, Ottley (1923, 1944) distinguished three taxa, namely, L. strigosus, L. strigosus var . hirtellus and L. tomentellus which she based on seed characteristics. She described the seed of L. strigosus, and L. strigosus var . hirtellus as: «cubical, notched at the hilum» and that of L. tomentellus as «globose to oval an occasional one cubical.»
Isely (1981) reduced L. tomentellus to a variety of L. strigosus. At the same time he established two phases, both for L. strigosus (phase 1 and 2) and for the var. tomentellus (phase 1 and 2) based on the fact that the phases represent «aberrant forms or intermediates.»
This study redefines the characteristics found in specimens of L. strigosus var . tomentellus from Lower California and Sonora.
Materials and Methods
The specimens studied were from (MEXU), Herbario Nacional de Mexico, Instituto de Biologia, Universidad Nacional Autónoma de Mexico. The acronym for the herbarium is given according to Holmgren et al. (1990). The morphological characters were examined with a Wild M 8 stereoscopic microscope equipped with a camera lucid. The topographic features of the testa were examined from whole seeds and portions of them by means of a Jeol JSM T100 scanning electron microscope (SEM). Drawings of the characters were prepared.
Results and Discussion
According to morphological characteristics, the specimens studied have been separated in groups as follows:
Group 1.
- Leaves greenish, 2 — 3 cm length. Leaflets 8 — 12 mm length. Peduncles 10 — 30 mm. Bract 1 — 2 (-3) leaflets. Flowers 7 — 8 mm. Standard frequently panduriform. Legume 20 — 25 mm x 1 — 2 mm. Ovules numerous, circular in lateral view, hilum superficial. Seeds non developed.
LOWER CALIFORNIA. Western base of Cocupah Mts., on shores of Laguna Maguata, C. Epling, M. Darsie, W. M. Stewart and W. M. Robison, s. n. Feb-19-1933 (552731 MEXU).- Loc. Puerto Refugio, Punta Norte de la Isla Angel de la Guarda, Mpio. Ensenada, 029º 33' 00 N lat, 113º 34' 00 W long, Elev. 50 m s. n. m. Pedro Tenorio L. 10849, C. Romero de T., Feb-07-1986. Desierto sarcocaulescente, suelo arenoso-pedregoso (523662 MEXU).
SONORA. Tiburon Island, Ensenada Blanca, vicinity 28º 59' N lat, 112º 29½' W long, Joe Edmundson; Alexander Russell, R. S. Felger , R.S.F. 17276, Feb-20-1968. (447029 MEXU).
Group 2.
- Leaves greenish, cinereous, 0.8 — 2 cm length. Leaflets 4 — 6 (-10) mm length. Flowers 4.5 — 6 mm, subsessiles or peduncled. Peduncles, when present 2 — 10 mm. Bract absent. Standard non panduriform. Legume 15 — 20 mm x 1.5 — 2 mm; incurved, falcate, sometimes slightly straight at maturity, and impressed between seeds. Seed globose, spheroid or square; outline in lateral view circular, round or quadrangular; 1 — 1.15 mm; yellowish, mottled; surface smooth or rugose, occasionally sinuate (at 40 x or less); lens discernible or prominent; hilum superficial; micropyle bifurcate. Testa topography reticulate with or without mounds.
LOWER CALIFORNIA. Loc. Desierto de Vizcaino, Arroyo San José de Castro, Mpio. Mulejé. Elev. 160 m s. n. m.; Jorge Cancino Hernández 6, Jun-26-1983. Hierba anual de 7 cm . Abundancia regular. Vegetación circundante matorral subinerme, vegetación halófila, en potrero. (354700 MEXU).- Loc. Desierto de Vizcaino, E de Bahía Asunción, Mpio. Mulegé. Jorge Cancino, Carlos Plata, C. 68; Feb-11-1984. Hierba anual escasa, 10 — 15 cm altura. Vegetación primaria de ecotono, duna mat. halófilo; suelo arenoso. (428089 MEXU).- Loc. La Bocana, Mpio. Santa Rosalía, 26º 53' N lat, 113º 44' W long. Elev. 20 m s. n. m. Pedro Tenorio L 12927, C. Romero T. Apr-17-1987. Hierba escasa, flores amarillas. Vegetación de dunas; suelo amarillo arenoso. [(282843 MEXU),both L. strigosus var. tomentellus and L. salsuginosus var. brevivexillus are on the same sheet].
SONORA. Tiburon Island, Ensenada de La Perra; vicinity 28º 47' N lat, 112º 16' long. R. S. Felger, J. Edmundson, N. Thomas, R. S. F. 17724, Apr-12-1968. (453698 MEXU).
Group 3.
- Leaves greenish, cinereous, 0.8 — 2 cm length. Leaflets 4 — 6 (-10) mm length. Flowers 4.5 — 6 mm, subsessiles or peduncled. Peduncles, when present 2 — 10 mm. Bract absent. Standard non panduriform. Legume 10 — 15 mm x 2 — 3 mm; straight and distally incurved, and not impressed between seeds. Fruit broader than of the group 2 relative. Seed laterally compressed, irregular; outline in lateral view circular, rarely quadrangular; 1.4 — 1.6 mm; light yellow, mottled; surface sinuate, rugose (at 40 x or less); lens prominent; hilum sunken in a lateral notch; micropyle deltoid. Testa topography papillose, with or without small mounds.
LOWER CALIFORNIA. Loc. San Ignacito, 14 km al SW de Cataviña, por la carr. transpeninsular, Mpio. Ensenada. 29º 47' N lat, 114º 45' W long. Elev. 640 m s. n. m. Pedro Tenorio L. 13110, C. Romero de T. Apr-28-1987. Hierba postrada, abundante, fl. amarilla, fr. inmaduro. Vegetación matorral desértico, primaria; suelo arenoso amarillo. [(155141MEXU), specimen corresponds to L. strigosus var. tomentellus, the envelope attached contains a mixture of the specimen L. strigosus var. tomentellus with L. salsuginosus var. brevivexillus].
SONORA. On hillsides of volcanic rock 2.5-3 mi N of Sáric, approx. 31º 07' N lat, 111º 20' W long. Elev. 2900 ft.; Grady L. Webster 22517, Mar-26-1978. Scrub of mesquite, saguaro, Cercidium, et al. Postrate, fls. yellow. (305643 MEXU).- Coast of the Gulf of California near the mouth of the Rio Concepcion, 10.6 mi. NE of El Desemboque on the road toward Caborca. Near 30º 40' N lat, 112º 57' W long. Elev. 100 ft. A. C. Sanders, M. Dimmitt, G. Montgomery, et al. 3479, Mar-7-1983. Sandy coastal flats with low dunes; creosote Bush Scrub with Larrea and Ambrosia dunosa. A fairly common yellow-flowered annual. (358773 MEXU).- Loc. km 71 de la carr. Sonoyta-San Luis Río Colorado. 32º 04' N lat, 113º 34' W long. Alvaro Campos V 4435a, J. L. Panero, L. I. Cabrera, Feb-28-1992. Hierba 20 cm altura, fl. blanca, fr. verde, frecuente. Vegetación matorral espinoso con Opuntia. (578101 MEXU).
- Group 1 characteristics correspond to L. strigosus var. tomentellus «phase 1» according to Isely (1981).
- Seed characteristics of the group 2 agree with the description of L. tomentellus by Ottley (1944), whereas seed characteristics of group 3 relate to descriptions of L. strigosus.
- Characteristics of groups 2 and 3 agree with the description of L. strigosus var. tomentellus by Isely (1981).
- Fruit and seed characteristics delimit two forms belonging to L. strigosus var. tomentellus.
Group 2 fruit incurved, falcate and seed with the hilum superficial.
Group 3 fruit distally incurved and seed with the hilum sunken in a lateral notch.
- I informally named «phase 3» to group 2, and «phase 4» to group 3.
Acknowledgments
I express my appreciation to Curators of the Herbario Nacional de Mexico (MEXU). I also thank Prof. William F. Grant for his helpful comments on the manuscript, and Rafael Urrejola for technical assistance using SEM.
PRODUCTION AND SOIL ENHANCING LEGUME LIVING MULCH SYSTEM FOR AGRONOMIC CROPS
N. L. Hartwig
Prof. of Weed Sci., Dept. of Agronomy, Pennsylvania State University, University Park, PA. 16802
ABSTRACT
Crownvetch ( Coronilla varia L.) and birdsfoot trefoil ( Lotus corniculatus L.) can be used as perennial living mulches in the production of corn ( Zea mays L.), soybeans ( Glycine max L.) small grains and forages. The primary benefit is the almost total reduction in soil erosion. Other benefits are enhanced productivity through soil conservation, increased soil organic matter and organic nitrogen, improved soil tilth, better footing during spring planting and fall harvesting seasons when it might otherwise be too wet to get into the field. Positive side effects include a reduction in environmental pollution from soil, nutrient and pesticide runoff, recycling of nutrients from deeper in the soil profile and more flexibility in meeting soil erosion criteria, including increasing the amount of corn and soybeans that can be grown on sloping cropland than otherwise would be allowed.
With the recent introduction of imidazolinone resistant (IR) corn and a weed control program based on imazethapyr, it is now possible to establish these legumes in corn without injuring the corn or the legume ground cover. Crownvetch is very slow to establish but when once established it will persist forever with the right management. Birdsfoot trefoil provides quick cover but gradually thins out over a period of years as a result of crownvetch competition and chemical suppression, leaving a predominately crownvetch cover. Corn of any kind can be planted into a one year old stand of birdsfoot trefoil and crownvetch using a recommended rate of rimsulfuron + thifensulfuron (Basis) for weed control with little or no injury to the cover crop or corn. Atrazine at a rate of 0.5 to 0.75 lb/A needs to be tank mixed with Basis to suppress the birdsfoot trefoil so it won't compete with the corn. Generally corn yields have not been suppressed when cover crop suppression is 95 to 98% for the first six weeks after planting. Fortunately crownvetch and to some extent birdsfoot trefoil will recover and provide up to 80% ground cover by fall even after suppression of this magnitude early in the summer.
Birdsfoot trefoil that is one year old and crownvetch that is two or more years old will tolerate 0.5 lb/A of glyphosate applied at about the time dandelion ( Taraxacum officinale Weber in Wiggers) is in bloom. This makes it possible to plant Roundup Ready¨ soybeans and use low rates of glyphosate for weed control and crownvetch or birdsfoot trefoil suppression. Roundup Ready¨ soybean yields up to 60 bu/A were obtained when planted into crownvetch in 1996 but yields up to 75 bu/A were obtained where there was no cover crop. It would appear that some refinement of this system may be necessary to prevent soybean yield suppression when planting into a crownvetch or birdsfoot trefoil living mulch.
Small grains and alfalfa have also been planted into crownvetch and grown without a loss in yield and without losing the cover crop. A blanket treatment of glyphosate or paraquat is commonly necessary before planting small grains or alfalfa to suppress the cover crop for the first six weeks of crop growth. Post treatments may be necessary for annual or winter annual weed control. Two herbicides that crownvetch will not tolerate are clopyralid and 2,4-DB but it will tolerate recommended rates of most other small grain or alfalfa herbicides and still be there in sufficient amounts so reseeding is not necessary when rotating back to corn.
PRELIMINARY ISOZYME DATA FOR LOTUS GLABER (SYN. L. TENUIS) AND LOTUS CORNICULATUS
Esteves, P.; Kade, M. and O.H. Caso
Centro de Ecofisiología Vegetal (CONICET)
Serrano 669
1414 Buenos Aires. Argentina
Two species of the genus Lotus are agriculturally important in Argentina because they are adapted to harsh environmental conditions marginal for alfalfa production. Lotus corniculatus L. is the main forage legume in Entre Ríos Province (Vertisol soils) and L. glaber Mill. has become naturalized along the Flooding Pampa (Molisols and Alfisols).
In spite of the mentioned characteristics practically no breeding efforts have been performed on these species in Argentina in order to increase their productivity and persistence.
The basis of any breeding program is to identify and quantify the species variability (Brown, 1978). To manage this, one possibility is to characterize isozyme polymorphisms and their distribution within and among populations (Tanksley and Orton, 1983; Ibañez et al., 1993). Indeed, isozyme patterns were used to elucidate the origin of L. corniculatus (Raelson and Grant, 1988). It was proposed that L. corniculatus is an allotetraploid being probably L. glaber and/or L. alpinus the maternal parents of the original hybrid (Ross and Jones, 1985). To our knowledge, no such studies have been performed in L. glaber.
In this context, preliminary results of isozyme polymorphisms were investigated, including other enzyme systems, in order to assess the extent of isozyme variability among and within the Argentine cultivars of L. glaber and L. corniculatus.
Experimental procedures
Plant material : Commercial seeds of L. glaber (2n=2x=12) cv. Tresur Chajá and L. corniculatus (2n=4x=24) cv. El Boyero INTA were subjected to chromosome number determination and germinated following ISTA Rules (1985). When seedlings developed the first leaves, they were transferred to greenhouse conditions (15-25C) during 60 days.
Isozyme electrophoresis: To obtain crude extracts, leaf material was crushed thoroughly in chilled mortars with cold extraction buffer (1:1,5 w:v). Each sample consisted of young leaflets of at least 5 plants for each species. Experiments were replicated twice with similar results. Extracts were absorbed onto 10 x 5 mm wicks of filter paper (Whatman No. 3) and inmediately inserted into slots performed in the starch gel. Electrophoresis was carried out using 11% starch (Sigma) gels prepared with a tris-citrate pH 7.0 buffer for malate dehydrogenase (MDH), 6-phosphogluconate (6-PG) and aspartate aminotranspherase (AAT), tris-citrate/lithium borate pH 8.3 buffer for esterase (EST) and diaphorase (DIA) and histidine/citric acid pH 5.7 buffer for acid phosphatase (ACP). These methods and staining procedures to resolve isozymes are described elsewhere ( Scandalios and Sorensen, 1977).
Gels were incubated at 37C for one hour, in the dark; then they were fixed in methanol 50%.
Results
The enzymes characterized displayed different patterns for each cultivar analyzed, with the exception of AAT and 6-PG. There was an apparent monomorphism among and within L. glaber and L. corniculatus cultivars for these isozymes.
MDH produced different electrophoretic patterns for each species showing the greatest variability inside the cultivars evaluated. Lotus glaber exhibited three patterns, which had two or three bands in different possitions. That pattern composed of two bands was also found in some L. corniculatus individuals . L. glaber samples consisted of one or three bands resulting in four different patterns.
EST showed two isozyme patterns in each species: L. glaber samples produced a third esterase band not found among L. corniculatus patterns, but both cultivars shared the pattern composed of two variable bands.
DIA enzymes were only evaluated in L. glaber and two different electrophoretic patterns were characterized consisting of two bands each.
Patterns of the ACP system provided the greatestdifferentiation between species. The cathodal region of the ACP gels in both species showed a common band. However, in the anodal region L. glaber ACP bands were almost always faster than L. corniculatus bands.
Discussion
Differences in electrophoretic patterns of isozymes for cv. Tresur Chajá ( L. glaber) and cv. El Boyero INTA (L. corniculatus) were detected between and among cultivars. MDH, EST and ACP systems showed some same patterns. Such a finding may be related to the presumed hybrid ancestry of L. corniculatus. Ross and Jones (1985) suggested that either L. alpinus and/or L. glaber could be the maternal parent of the original hybrid.
Further studies would confirm if ACP system can be used effectively to differentiate one cultivar from another. The fast band for L. glaber pattern showed a higher mobility than the same band for L. corniculatus. This difference was not observed to be constant, but it is evident from this survey that its frequency is high. It is clear that these results need to be confirmed with a larger set of individuals, and perhaps, with small refinements of the procedure. Besides, Raelson and Grant (1988) did not examined ACP system in their review concerning the origin of L. corniculatus.
Electrophoretic analysis, which can be also performed on ungerminated seeds, would resolve questions of seed identification. L. glaber and L. corniculatus seeds are very similar, therefore a relatively rapid and accurate method of discriminartion, as well as the flavonol analysis based on a chromatographic procedure (Kade et al., 1997), would facilitate classification of seed samples.
THE INTERNATIONAL ASSOCIATION FOR PLANT TAXONOMY (IAPT) ANNOUNCES:
REGISTRATION OF PLANT NAMES
Test and Trial Phase (1998-1999)
Introduction
Subject to ratification by the XVI International Botanical Congress (St Louis, 1999) of a rule already included in the International code of botanical nomenclature (Art. 32.1-2 of the Tokyo Code), new names of plants and fungi will have to be registered in order to be validly published after the 1st of January 2000. To demonstrate feasibility of a registration system, the International Association for Plant Taxonomy (IAPT) undertakes a trial of registration, on a non-mandatory basis, for a two-years period starting 1 January 1998. The co-ordinating centre will be the Secretariat of IAPT, currently at the Botanic Garden and Botanical Museum Berlin-Dahlem, Germany. Co-ordination with present indexing centres for major groups of plants is being sought, in view of their possible active involvement at the implementation stage. The International Mycological Institute in Egham, U. K., has already accepted to act as associate registration centre for the whole of fungi, including fossil fungi.
Registration procedure
The co-ordinating registration centre (IAPT Secretariat), and any associated centre operating under its auspices, will register and make available all names of new taxa, all new combinations or rank transfers that are brought to their attention in one of the following ways:
by being published in an accredited journal or serial;
by being submitted for registration (normally by the author or one of the authors), either directly or through a national registration office; or
(for the non-mandatory trial phase only) as a result of scanning of other published information by the registration centres' own staff.
Registration by way of publication in accredited journals or serials
For a journal or serial to be accredited, its publishers must commit themselves, by a signed agreement with the IAPT, to
point out any nomenclatural novelties in each individual issue of their journal or serial, either by including a separate index of novelties or in another suitable, previously agreed way;
submit each individual issue, as soon as published and by the most rapid way, to a pre-defined registration office or centre.
Accredited journals and serials will be entitled, and even encouraged, to mention that accreditation on their cover, title page or in their impressum.
A permanently updated list of accredited journals and serials is being placed on the World Wide Web (http://www.bgbm.fu-berlin.de/iapt/registration/journals.htm). This list will be published annually in the journal Taxon.
Registration by way of submission to registration offices
Authors of botanical nomenclatural novelties that do not appear in an accredited journal or serial (but e.g. in a monograph, pamphlet, or non-accredited periodical publication) are strongly encouraged to submit their names for registration — and will be required to do so once registration becomes mandatory — in the following way:
all names to be registered are to be listed on an appropriate registration form, using a separate form for each separate publication;
the form (in triplicate) must be submitted together with two copies of the publication itself, either to a national registration office (see below) or, optionally, directly to the appropriate registration centre. Reprints of articles from books or non-accredited periodicals are acceptable, provided their source is stated accurately and in full;
one dated copy of each form will be sent back to the submitting author in acknowledgement of effected registration.
Registration forms can be obtained free of charge (a) by sending a request to any registration office or centre, by letter, fax or e-mail, or (b), preferably, by printing and copying the form as available on the World Wide Web (http://www.bgbm.fu-berlin.de/iapt/registration/regform.htm).
Registration offices are presently being arranged for in as many different countries as possible. They will serve (a) as mailboxes and forwarding agencies for registration submissions and (b) as national repositories for printed matter in which new names published locally appear.
A permanently updated address list of all functioning national registration offices is being placed on the World Wide Web (http://www.bgbm.fu-berlin.de/iapt/registration/offices.htm). This list will also be published annually in the journal Taxon.
Registration date
The date of registration, as here defined, will be the date of receipt of the registration submission at any national registration office or appropriate registration centre. For accredited journals or serials (and, for the duration of the trial phase, for publications scanned at the registration centres), it will be the date of receipt of the publication at the location of the registration centre (or national office, if so agreed).
For the duration of the trial phase, i.e. as long as registration is non-mandatory, the date of a name will, just as before, be the date of effective publication of the printed matter in which it is validated, irrespective of the date of registration. Nevertheless, the registration date will be recorded, for the following reasons:
to make clear that the name was published on or before that date, in cases when the date of effective publication is not specified in the printed matter;
to assess the time difference between the (effective or stated) date of the printed matter and that of registration, since it is envisaged that the date of registration be accepted as the date of names published on or after 1 January 2000.
It is therefore in the interest of every author to submit nomenclatural novelties for registration without any delay, and by the most rapid means available.
Access to registration data
Information on registered names will be made publicly available as soon as feasible, (a) by placing them on the World Wide Web without delay in a searchable database (http://www.bgbm.fu-berlin.de/iapt/registration/regdata.htm), (b) by publishing non-cumulative lists biannually, and ©, hopefully, by issuing cumulative updates on a CD-ROM-type, fully searchable data medium at similar intervals.
Registration as a positive step (comments of Karen L. Wilson, Royal Botanic Gardens, Mrs Macquaries Road, Sydney, N.S.W. 2000, Australia.]
Registration of nomenclatural novelties seems to me a natural way to go, heading into the 21st Century. It will enable us to find quickly what new names have been published, and to be sure that we have not missed any new name hidden in the paper mountain of botanical literature that comes out each year around the globe. This is particularly important for one-off publications (floras, field guides, etc.), which are notorious for `hiding' new names.
Some people seem to think that registration implies censorship, but this is wrong. As in the current Index kewensis all names will be listed, and without comment as to status, and as soon as received at one of the registration centres. My only caution to those looking at the mechanisms for making registration effective is that they should ensure there is a large network of registration centres or offices spread evenly around the world. This is necessary to make it easy to submit novelties for registration, given the apparently worsening state of mail services in all areas.
DATABASE ON THE TAXONOMY AND MORPHOLOGY OF THE GENUS LOTUS S.L. (LEGUMINOSAE-PAPILIONOIDEAE-LOTEAE)
The taxonomy of the genus Lotus is rich in complicated problems. On the one hand, the boundaries of the genus and its subdivisions are often discussed. On the other hand, the delimitation of species and ifraspecific taxa is sometimes doubtful, as for instance in Lotus corniculatus complex, Lotus creticus complex, Lotus angustissimus complex, and in a group of perennial species of subgen. Syrmatium.
In a broad sense, the genus Lotus comprises, according to different views, from 100 species (Polhill, 1981) to 176 species (Kirkbride,1994) on all continents except the Antarctic. The majority of species occur in the Mediterranean region, Macronesia, and in the western part of North America, especially in California. Several species are cultivated as forage plants.
J.H. Kirkbride (1994) presented the worldwide Checklist of the species of Lotus s.l.
The aim of the present database is maintaining data on the taxonomy, morphology and geography of Lotus species. Taxonomic boundaries of the genus Lotus are accepted according to J.H. Kirkbride (1994), i.e. the genus is treated in the wide sense.
FLORIN Information System developed by DataX/FLORIN Inc. was chosen as a basic software for maintaining Lotus database. The System allows to store in a database large amounts of information, keep them in a good order, browse data using queries-by-example, generate configurable reports, labels and digital maps for herbarium specimens, and includes other useful possibilities.
The database is maintained by a personal FLORIN version for MS-DOS. It contains various information, such as morphological descriptions, bibliographic citations, taxonomic notes for taxa of different ranks, and also data on type material and herbarium specimens.
The taxonomic part of the database is being regularly transferred to Unix platform, and the current version of it is available in the Internet (the URL:http://www.florin.ru/florin/db/lotus.htm). Data on herbarium specimens and maps of distribution areas of species and ifraspecific taxa exist only in a personal MS-DOS version of the Database.
On the first step of database compilation nomenclatural data were included. The latest version of the database (November 1997) contains all specific names published in the genus Lotus since 1753 (507 names).The first citation of each name is available. 193 species of Lotus are accepted and attached to sections and subgenera according to our point of view. 34 names are included in database as incertae sedis. The remaining 286 names are treated as synonyms.
On the second step we plan to insert in the database the types of all taxa. At the present time, 158 types of species and ifraspecific taxa are included. Now the database also contains about 100 morphological descriptions and 350 citations of herbarium specimens (with geographical coordinates for the majority of them).
References
Kirkbride, J. H., Jr., 1994. — Taxonomic Circumscription of the Genus Lotus Linnaeus (Fabaceae, Loteae), Its Tribal Position, and Its Species, pp. 11-15, in Proc. 1 Intern. Lotus Symposium. St.Louis.
Polhill, R. M., 1981. — Loteae DC., Coronilleae (Adans.) Boiss., pp.371-375, in R. M. Polhill & P. H. Raven (eds.) Proc. Intern.Legume Conf., Kew, 24-29 July 1978. 2. Advances in Legume Systematics 1. Kew.
Current Literature
Seed pod shattering in the genus Lotus (Fabaceae): a synthesis of diverse evidence. Grant, W. F. Canadian Journal of Plant Science 76 (3): p.447-456. 1996.
Birdsfoot trefoil ( Lotus corniculatus L.) is a perennial dehiscent species with an indeterminate growth habit. Pod shattering (shedding) has been a major problem, seed loss was high due to continuous flowering and time of pod maturity. The anatomy of the pod plays a role in pod shattering. A change in the orientation of pericarp cells, unequal swelling and shrinkage occurs, and a lower lignification of the mesocarp were considered major causes of shattering. The relative humidity (RH) at the time of harvest was also a major factor. The critical RH for dehiscence varied with genotypes between 35 and 49%. There was no correlation for pod dehiscence between plants grown to maturity under greenhouse conditions and the same plants grown in the field. Management practices (time of harvest, clipping early in the season, misting, mowing and turning the windrow during drying, and desiccants) were not successful in controlling pod shattering. Shattering resistance is highly heritable and is considered to be controlled by more than one gene in Lotus. Breeding to reduce shattering through recurrent selection was unsuccessful. Attempts to transfer the indehiscent seed pod trait from distantly related indehiscent species via interspecific hybridization, diploid bridge species, amphidiploidy, and backcrossing to birdsfoot trefoil, or similarly by interspecific somatic hybridization, have shown promise. The molecular approach has so far not been attempted but since genetic transformation can be carried out in Lotus, this avenue should be investigated.
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