Boron deficiency in lentil: Yield loss and geographic distribution in a germplasm collection

In a programme to improve the production of lentil (Lens culinaris Medikus) , germplasm was introduced into Nepal. However, the evaluation of exotic ge rmplasm in the Chitwan region of Nepal revealed a striking micronutrient de ficiency problem. Landraces from Nepal had no deficiency symptoms, whereas 82% out of 494 exotic accessions showed severe chlorosis and stunting. Boro n (B) deficiency was revealed as the primary cause of the problem and the f irst limiting nutrient, because an exotic genotype, which exhibited the sym ptoms, yielded only 103 kg seed/ha, but produced 1367 kg seed ha with the a pplication of 0.5 kg boric acid/ha, a 13-fold yield increase. There was als o a significant but lower response in yield (20%) to applied Zn. Exotic ger mplasm from various countries showed differences in B-deficiency symptoms. Accessions from Syria, representative of the Mediterranean region where len til originated, all exhibited B-deficiency symptoms. Accessions without B-d eficiency symptoms were mainly from Bangladesh (37% accessions free of B de ficiency). In a subsequent trial to estimate yield losses, landraces from N epal, which exhibited no deficiency symptoms, were B efficient and gave a m ean seed yield of 1173 kg/ha. In contrast, 10 exotic lines exhibited severe symptoms and gave no seed yield. In summary, the study revealed that, in s oil low in B, striking genetic differences in B efficiency associated with geographic origin are apparent which may lead to complete yield loss in B-i nefficient lentil germplasm.