8. Growth and yield descriptors of rice influenced by transplanting date

Abstract

Boro rice faces two-way challenges – cold injury at different stages of growth due to early transplanting and early or pre-monsoon rain and flash flood for the late transplanting. An experiment was conducted to investigate the yield loss percentage of hybrid boro rice cultivars due to late transplanting. A two-factor experiment viz. two rice cultivars and three transplanting dates, was laid out in a randomized complete block design with three replications. All the studied morphological descriptors viz. plant height, number of tillers (total, effective and non-effective) and leaf size (length and width), and some of the yield and yield contributing descriptors viz. panicle length, length of primary branch, number and length of secondary branch, grain and straw yield and harvest index, were significantly influenced by both cultivars and transplanting times. Transplanting time had a little/insignificant effect on grain descriptors e.g., number panicle–1 , size (length, breadth and thickness), 1000-grain weight, etc. Although the cultivar Saru Madina produced longer panicle, higher number of primary and secondary branches panicle–1 and number of filled grains panicle–1 ; it also produced higher number of unfilled grain in primary and secondary branches (5 and 10 folds, respectively) compared to Ispahani-2. The maximum grain yield (7.81 t ha–1 ) was harvested from Ispahani-2 at 1st January transplanting and the lowest (6.29 t ha–1 ) from Saru Madina at 30th January transplanting. Boro rice cultivars should be transplanted on or before 15th January for grain yield maximization; the grain yield reduction reached up to 17% when transplanting operation done on 30th January.