Annual feed legume yield and quality in dryland environments in north-west Syria: 1. Herbage yield and quality

Abstract

Promising accessions of common vetch ( Vicia sativa L.), narbon vetch ( Vicia narbonensis L.) and grasspea ( Lathyrus sativus L.) adapted to non-tropical dry areas of Central and West Asia, and North Africa, where mean annual rainfall is 200–350 mm have been identified, but their herbage yield and quality under on-farm conditions are not documented. An on-farm study was conducted over two growing seasons in non-tropical wet and dry semi-arid environments in north-west Syria to evaluate effects of 0, 30, and 60 kg P/ha phosphate fertilizer rates on herbage yield and concentrations of crude protein (CP), acid detergent fibre (ADFom), neutral detergent fibre (aNDFom), and in vitro organic matter (OM) digestibility (IVOMD) in the herbage 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 quality herbage yield for specific environments. A split-plot design with phosphate fertilizer rates as main-plots and accessions as sub-plots was used. For each species, herbage yield was determined when 0.50 of the plants had flowered. Annual total rainfall averaged 283 mm and 140 mm for the wet and dry environments respectively during the two growing seasons. Herbage yield and the determinants of herbage quality varied (P<0.05) among the accessions and species within environments and growing seasons. The phosphate fertilizer rate×accessions and phosphate fertilizer rate×growing season interactions had no effect on herbage yield and quality. Herbage yield ranged from 695 to 3471 kg DM/ha and 404 to 2595 kg DM/ha in the wet and dry environments respectively. In the wet environment, the CP, ADFom, aNDFom and IVOMD concentrations ranges were: 156–258, 223–292, 243–349 g/kg DM and 603–670 g/kg OM respectively. Corresponding ranges for the dry environment were: 153–267, 186–275, 250–323 g/kg DM, and 565–648 g/kg OM respectively. The CP and aNDFom were associated ( r = −0.45 to −0.57, P<0.01) in the three species, while the ADFom and IVOMD were correlated ( r = −0.77, P<0.01) in the vetches. Grasspea accession 445 and narbon vetch accessions 2561 and 2380 showed high potential for quality herbage production in both environments.