A. M. Abd El Moneim

Current status and future strategy in breeding grasspea (Lathyrus sativus)

Efforts in grasspea (Lathyrus sativus) improvement have increased since the development of lines that are very low in the neurotoxin Beta-N-oxalyl-L-alpha-beta-diamino propionic acid (ODAP); also referred to as Beta-N oxalyl-amino-L-alanine (BOAA). Many programs now address several related aspects of improvement simultaneously. These include reduced ODAP concentrations, insect and disease resistance, nitrogen fixation, agronomic practices, fodder and forage production, and components for increased yielding ability. The coordinated, multidisciplinary approach now being applied to the genetic improvement of grasspea should allow the potential of this largely neglected grain legume to be fully realized.

Nutritional and antinutritional characteristics of selected Vicia genotypes

Abstract Mature seeds of Vicia narbonensis (91 lines), Vicia sativa (23 lines), Vicia ervilia (16 lines) and Vicia palaestina (16 lines) were evaluated for crude protein (CP), protein precipitable tannin (PPT), vanillin-HCl catechin equivalent (CE) and trypsin inhibitor activity (TIA). Other chemical and in vitro characteristics measured included ash, organic matter (OM), neutral detergent fibre (NDF), acid detergent fibre (ADF), in vitro organic digestibility (IVOMD) and in vitro dry matter (DM) digestibility (IVDMD). Crude protein content ranged from 264.38 ± 6.34 g kg −1 DM in V. ervilia to 341.87 ± 8.55 g kg −1 DM in V. palaestina with all species showing little intraspecies variability. The DM, OM and ash contents of all the lines were similar. However, the ADF and NDF values for V. narbonensis were significantly ( P P V. ervilia paralleled the relatively lower ADF and NDF values. PPT was mainly restricted to V. narbonensis while none was detected in any of the lines of either V. sativa or V. ervilia . Tannin expressed as CE was no more than 8.27 g kg −1 in any of the species and seven of the 91 lines of V. narbonensis had no detectable CE levels. There was considerable intraspecies variability in CE as indicated by the high coefficients of variation (CV), which ranged from 17.48% in V. palaestina to 68.99% in V. sativa . In comparison with most conventional legumes, TIA values were generally low in all the species, ranging from 0.36 g kg −1 DM in selection IFLVP 2524 to 5.00 g kg −1 DM in IFLVS 2560. Values for TIA in V. palaestina were particularly low (0.51 ± 0.13 g kg −1 DM) and a CV of 25.86% suggests that selection for lower inhibitor levels is possible. Seed weight was significantly ( P V. sativa and V. palaestina , while CP was weakly negatively correlated ( r = −0.48) with TIA among the V. sativa genotypes. There was no significant relationship between seed weight and TIA in any of the species investigated.

Prediction of phenolics and tannins in forage legumes by near infrared reflectance

Near infrared (NIR) spectroscopy calibrations for measures of tannins and nutritive value were made on a set of 40 hays and straws of Vicia and Lathyrus spp. by the modified partial least squares (MPLS) method and were evaluated by cross-validation. They successfully predicted, in the dry matter, 4.6–34.1 g kg−1 total phenolics with a cross-validation R2 of 0.95 and a SECV of 1.68 g kg−1, 1.3–23.1 g kg−1 total tannins (R2 = 0.89, SECV = 1.84 g kg−1) and 0.5–30.3 g kg−1 condensed tannins (R2 = 0.93, SECV = 2.34 g kg−1). In multiple regression and MPLS calibrations, a wavelength close to 2.144 μm was common to all measures of tannins, and was attributed to condensed tannins and its flavanoid precursors. The biological activity of tannins on rumen microbes, measured as a 0–6.9% effect on gas production with rumen liquor in vitro, was less precisely predicted by MPLS (R2 = 0.49, SECV = 1.49%). The biological activity per gram of chemical tannins could not be predicted by NIR spectroscopy in the material studied. Acid detergent fibre, neutral detergent fibre, crude protein and gas production in vitro were predicted with R2 = 0.95 to 0.96 (SECV = 18.2, 24.8, 10.1 g kg−1 or 7.2 mL g−1).

Seed yield and hardseededness of two amphicarpic pasture legumes (Vicia sativa ssp. amphicarpa and Lathyrus ciliolatus) and two annual medics (Medicago rigidula and M. noeana)

Yields and hardseed breakdown of underground and aerial seeds in subterranean vetch (Vicia sativa ssp. amphicarpa) and lathyrus (Lathyrus ciliolatus) and aerial seeds of Medicago rigidula and M. noeana were compared at Tel Hadya, near Aleppo, in north Syria between 1990 and 1992. Underground and aerial seed and straw (mature herbage) yields were measured at maturity in the first spring, and hardseed breakdown over the following summer, autumn and winter. Regenerating herbage production was measured in the second spring. In the establishment year (292 mm rainfall) the medics produced twice as much straw as the amphicarpic species. In contrast, seed yields were less than half: M. rigidula and M. noeana produced 412 and 110 kg/ha respectively, while subterranean vetch and lathyrus produced 1174 and 736 kg/ha. More than 95 % of the total seed yield of the amphicarpic legumes was underground. Underground seeds of the amphicarpic legumes were larger than aerial seeds, and almost 10 times as large as the medic seeds. Seeds of all species were > 90 % hard when newly set in summer. At the first seasonal rains > 95 % of underground seed had softened, compared with 5 and 40 % of the aerial seeds of vetch and lathyrus respectively. The medics remained > 90 % hardseeded. In laboratory tests, embryo dormancy was observed in all species prior to the onset of first seasonal rains. For the amphicarpic legumes, but not for the medics, embryo dormancy persisted into winter. In the field, and after all germination events, 900-1430 seeds/m 2 of subterranean vetch seed remained in the soil. This was considerably more than expected, based on the low levels of hardseededness and embryo dormancy observed in the laboratory. The results suggest that dormant seeds of the amphicarpic legumes need light to germinate. In the second year (353 mm rainfall), regenerating M. rigidula produced 5.3 t/ha compared with 3.4 t/ha by the best subterranean vetch from approximately equal numbers of seedlings. The amphicarpic legumes germinated later and over a more extended period than the medics, indicating that they could become weeds in a cereal/pasture rotation. However, the results suggest that in drier areas or in drier years the vetches will compare favourably with the medics in most respects. Clearly, subterranean vetch and lathyrus have great potential for pasture improvement in dry areas.

Sources of resistance to downy mildew in narbon (Vicia narbonensis) and common (Vicia sativa) vetches

Downy mildew (Peronospora viciae (Berk) de Bary) is an important disease of vetches (Vicia spp.) in the Mediterranean Region. Narbon and common vetch germplasm accessions originating from different countries, and advanced breeding narbon vetch genotypes, were evaluated for reaction to downy mildew for two seasons under field conditions. In narbon vetch, there were resistant sources from both germplasm accessions and advanced genotypes. From the germplasm accessions, 25 accessions were resistant while from the advanced breeding genotypes, 10 had resistance, with 2–3 ratings. In common vetch, many accessions were highly resistant to downy mildew. These were widely distributed in different countries, mainly Turkey, Italy, Syria and Iran. In general, common vetch had higher sources of resistance than the narbon vetch accessions. These new sources of resistance to downy mildew will be incorporated into the forage legume improvement project in a continuous effort to identify cultivars suitable for replacing fallow in the cereal-based cropping systems.

Evidence of gains in nutritional quality in Lathyrus sativus

By exploiting somaclonal variation a large number of stable low ODAP containing L sativus lines have been developed. Some of the low ODAP strains also have high yields. One such line, Bio L212 has been released. A few of the somaclones have been DNA finger printed. An ODAP degrading gene has been isolated and characterised from a soil microbe and has been cloned into an Agrobacterium strain for transforming L sativus.