Annual feed legume yield and quality in dryland environments in north-west Syria: 2. Grain and straw yield and straw quality

Abstract

Little is known about on-farm performance of promising accessions of common vetch ( Vicia sativa L.), narbon vetch ( Vicia narbonensis L.) and grasspea ( Lathyrus sativus L.) that are adapted to the non-tropical dry areas of Central and West Asia, and North Africa, where mean annual rainfall is 200–350 mm. An on-farm study was conducted over two growing seasons in non-tropical wet and dry semi-arid environments in north-west Syria to determine effects of 0, 30, and 60 kg P/ha phosphate fertilizer rates on grain and straw yields and concentrations of crude protein (CP), acid detergent fibre (ADFom), neutral detergent fibre (aNDFom), and in vitro organic matter (OM) digestibility (IVOMD) in the straws of 11 promising accessions of common vetch (2556, 2604 and Local), narbon vetch (2561, 2383 and 2380) and grasspea (445, 476, 519, 527 and Local), with the aim of identifying accessions with suitable adaptation and grain and quality straw yields for specific environments. A split-plot design with phosphate fertilizer rates as main-plots and accessions as sub-plots was used. Annual total rainfall during the two cropping seasons averaged 283 mm in the wet, and 140 mm in the dry environments. Grain and straw yields and straw quality varied ( P<0.05) among the accessions and species within environments and cropping seasons. The accession × phosphate fertilizer rate and growing season × phosphate fertilizer rate interactions had no effect on grain and straw yields and straw quality. The vetches produced more ( P<0.05) grain and straw than the grasspea, but the grasspea straw CP and IVOMD were higher ( P<0.05) than those of the vetches in both environments. Grain yield ranged from 472 to 2205 kg DM/ha and 254 to 1346 kg DM/ha in the wet and dry environments, respectively. Ranges for straw CP, ADFom, aNDFom and IVOMD in the wet environment were 71–130, 305–390, 431–438 g/kg DM and 486–533 g/kg OM, respectively. Corresponding ranges in the dry environment were 82–151, 272–369, 359–478 g/kg DM and 486–549 g/kg OM, respectively. In both environments, the ADFom and aNDFom were correlated to the CP ( r = −0.44 to −0.90, P < 0.01) and IVOMD ( r = −0.28 to −0.86, P < 0.01), and the CP and IVOMD were correlated ( r = 0.35–0.75, P < 0.01) in the three species. In terms of grain and quality straw yields, narbon vetch accessions 2383 and 2380 had high potential in both environments.