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

Abstract

In a programme to improve the production of lentil (Lens culinaris Medikus), germplasm was introduced into Nepal. However, the evaluation of exotic germplasm in the Chitwan region of Nepal revealed a striking micronutrient deficiency problem. Landraces from Nepal had no deficiency symptoms, whereas 82% out of 494 exotic accessions showed severe chlorosis and stunting. Boron (B) deficiency was revealed as the primary cause of the problem and the first limiting nutrient, because an exotic genotype, which exhibited the symptoms, yielded only 103 kg seed/ha, but produced 1367 kg seed ha with the application of 0.5 kg boric acid/ha, a 13-fold yield increase. There was also a significant but lower response in yield (20%) to applied Zn. Exotic germplasm from various countries showed differences in B-deficiency symptoms. Accessions from Syria, representative of the Mediterranean region where lentil originated, all exhibited B-deficiency symptoms. Accessions without B-deficiency symptoms were mainly from Bangladesh (37% accessions free of B deficiency). In a subsequent trial to estimate yield losses, landraces from Nepal, which exhibited no deficiency symptoms, were B efficient and gave a mean 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 soil low in B, striking genetic differences in B efficiency associated with geographic origin are apparent which may lead to complete yield loss in B-inefficient lentil germplasm.