Variation in Glucosinolate Contents and Quality Characteristics in the Seed of Radish (Raphanus sativus L.) along an Altitudinal Gradient in trans-Himalayan Ladakh

Abstract

Glucosinolates (GS) are amino acid derived secondary metabolites present specifically in Brassicaceae family. The effect of altitude (2800 m - 4000 m) on GS contents and seed quality characteristics in radish (Raphanus sativus L.) was investigated. The total GS in radish seed was 147.5±21.5 μmol/g DW, which included five aliphatic and four indolic GS compounds. Increasing altitude was related linearly to increase in total GS contents (R2 = 0.759). Among individual GS, glucoraphanin and glucoraphenin showed consistently increasing trend with altitude. Increasing altitude is related linearly to increase in 100 seed weight (R2 = 0.266) and seed yield per plant (R2 = 0.849). A steady decreasing trend was observed in seed moisture content (R2 = 0.831) and siliqua length (R2 = 786) with increasing altitude. Altitude of plant origin was positively correlated with GS contents (r = 0.900, p≤ 0.01), seed weight per plant (r = 0.919, p≤ 0.01) and geometric mean diameter (r = 0.661, p≤ 0.01), and negatively correlated with siliqua length (r = -0.880, p≤ 0.01), moisture content (r = -0.884, p≤ 0.01) and seed vigour index (r = -0.547, p≤ 0.01). Our results indicate that the concentration of GS in radish seed and seed quality traits can be significantly increased by growing plants at higher altitude.