Diversity of boron-toxicity tolerance in lentil growth and yield

Abstract

Boron (B) toxicity is increasingly being recognized as a problem in arid areas of West Asia, where lentil is widelygrown. This study investigated whether or not: (1 ) phenotypic variation of B-to xicity toler ance exists at the seedlingstage in lentil, (2) such variation persists to affect adult performance, and (3) there is geographical diversity inseedlin g tolerance. Four experiments were conducted in a green house. Boric acid was adde d and mixed uniformlyinto the soil-mix to prepare high-B soil. Expe riment I screened 77 lentil lin es randomly sele cted from ICARDA’sinter national nurseries. Visual growth score s and foliar B-to xicity symptom scores were taken 4–5 wee ks aftersowing, and used as an indicator for B-toxicity tolerance. In Exper iments I I and III, four selected lines werestudied beyond the seedling stage. In Experime nt IV, 231 lentil acc essions from seven di fferent countries/regionsof the world were screened . Ther e were highly sig nificant differences between the 77 lines in B-toxicity toleranceat th e seedling stage as indicated by their degree o f B-toxicity sympto m, and plan t growth. The two tolerant and twosensitive selections fro m Experi ment I showed diverse per formance up to maturity as reflected by their differencesin leaflet lo ss, dry mass reduction, and seed yield when grown in high-B soil. There were significant differences inB-toxicity tolerance between the 231 accessions. On average, accessions from Af ghanistan were the most tolerant,followed by those from India, Iraq, Syria, Europe , E thiopia, a nd Nepal.