Induction of variability for yield components in Indian mustard (Brassica juncea L. Czern & Coss) under acidic soil regime of Jharkhand.

Abstract Indian mustard (Brassica juncea L.) is the most important oilseed crop of the state of Jharkhand in India, where 78% of the cultivable soil is acidic, causing a sizeable yield reduction. Potential seed yield from such soils cannot be realized within existing varieties and therefore a mutation breeding approach has been followed to isolate mutants tolerant to acidic soil. Three doses of gamma-rays (900 Gy, 1000 Gy and 1100 Gy) and a combined treatment of gamma irradiation and 0.3% EMS were used for induction of mutation in the varieties 'Shivani' and 'Pusa Bold'. A total of 139,720 M2 plants (75,760 of 'Shivani' and 63,960 of 'Pusa Bold') were screened under acidic soil conditions (pH 4.8). A wide spectrum of variability for tolerance to soil acidity, earliness, seed colour, seed yield and yield components, and morphological traits was observed in the M2 generation. True-breeding mutants for different traits were confirmed in the M3 generation. Mutations were recorded in 'Shivani' and 'Pusa Bold', respectively, for secondary branch number (38 and 24), siliquae per plant (1223 and 562) and single plant seed yield (45.49 g and 34.84 g). In addition, a large spectrum of variability for morphological characters was identified.