EFFECTS OF SOWING SEASON ON HERBAGE AND SEED PRODUCTION OF GRASSPEA UNDER RAINFED CONDITION OF KHORAMABAD, IRAN

In order to study seed and dry matter (DM) yield and relationships among yield and agronomic traits, 11 lines of grasspea (Lathyrus sativus L.) obtained from the International Center for Agricultural Research in the Dry Areas (ICCADA) were sown in two growing seasons using randomized block design with three replications in autumn 2011 and spring 2012 in rainfed area of Khoramabad, Iran. Significant variation in all of traits except harvest index were observed due to sowing season. On an average, 9763 and 4708 kg ha-1 for DM yield and 3206 and 1423 kg ha-1 for seed yield were produced in autumn and spring sowing seasons, respectively. The lines of 449 and 387 gave good DM and seed yield, and they were introduced as improved varieties for cultivation. DM yield was positively correlated with straw yield and seed yield in both the sowing seasons and correlated with pods per plant, seeds per pod and pod length in spring season. Similarly, seed yield was positively correlated with straw yield, harvest index and pod number per plant for both the sowing seasons and with seeds number per pods in spring season. The results of principle component analysis (PCA) showed that the first four components (PC1 to PC4) accounted for 37, 28, 10 and 8 of the total variation, respectively. DM, straw and seed yield in the PC1, seeds per pod, pod length, pods per plant, flowering date and 100 seeds weight in the PC2, the pod height and stem length in the PC3 and finally the stem density in the PC4 components were identified as the important traits. Using Ward cluster method the 11 lines were grouped into 4 clusters. The lines in Cluster 1 coupled with late maturity had higher productivity for both DM and straw yield. The lines in Cluster 2 coupled with early maturity had higher productivity for both DM and seed yield. Clusters 3 and 4 had low and moderate productivity, respectively.