Growth and Yield Response of Five Elite Grass Pea (Lathyrus sativus L.) Genotypes to Varying Levels of Potassium

crop which is globally grown as a winter crop (Ali et al., 2002), such as in tropics and subtropics including Ethiopia, Burma, Morocco, India, Ecuador, Peru, Columbia and Pakistan ( Javaid et al., 2002).Its cultivation ranks fourth after soybean, groundnut and beans (Ashraf et al., 2011) and is known to maintain soil fertility through biological nitrogen fixation along with symbiotic rhizobium prevalent in its root nodules (Negi et al., 2006).Hence, it has been considered a valuable crop in the grass rotations and a biological Abstract | Adequate potassium (K) nutrition is known to increase crop yields, including legumes.However, very little is known about the K requirements of crops in Pakistan, especially grass pea (Lathyrus sativus L.).We evaluated K requirements of five elite grass pea genotypes in a field experiment.The experiment was organized in factorial block design with three replications.The study involved five commonly grown grass pea genotypes (Sel-B 111, Sel-449, Sel-190, Sel-1785 and Sel-945) and three K doses (0, 10 and 20 kg K ha -1 ).The results revealed that K nutrition and genotypic variation significantly (p<0.05)determined the yield of grass pea.However, their interaction remained non-significant for all the traits of grass pea under study.As expected, the increasing rate of K significantly (p<0.05)increased various growth traits and yield of grass pea genotypes.The crop supplied with 20 kg K 2 O ha -1 produced maximum branches per plant (5.2), pods per plant (32.3), seeds per pod (4.7), seed index (82.7 g) and seed yield (2589 kg ha -1 ) when compared with 0.0 and 10 kg K 2 O ha -1 .Interestingly, Sel-449 was the most responsive genotype to K nutrition which resulted in higher branches per plant (5.3), pods per plant (29.7), seeds per pod (4.5), seed index (87.3g) and seed yield (2504 kg ha -1 ) as compared to its counterparts.The genotype Sel-1785 was much closer to Sel-449 for its growth and yield traits.We conclude from the results of this study that a dose of 20 kg K 2 O ha -1 proved to be the most beneficial.Moreover, the grass pea genotype Sel-449 was more responsive to potassium nutrition as compared to other genotypes.Hence, we recommend growing of Sel-449 at 20 kg K 2 O ha -1 for obtaining maximum yield of grass pea.