author(s)
Pranab Barma, Sujit Sarkar, Sarkar RK, Moktan MW, Ali S, Rahaman FH and Burman RR

abstract
An on-farm trial was conducted at Darjeeling district of West Bengal; to evaluate the performance of IARI released improved rice varieties. Two rice varieties were used for the study: Pusa-44 (non-lodging variety, 140-145 days) and Pusa Sugandh-5 (tolerance to shattering, 120-125 days). From the trial, it was observed that both the improved rice varieties recorded higher grain yield (Pusa-44: 3.54 t/ha and Pusa Sugandh-5: 3.01 t/ha) as compared to the farmers’ practiced variety Kalonunia (1.93 t/ha). Among the yield components assessed, the number of effective tillers per plant; the number of grains per panicle and 1000 grain weight contributed more to the yield and are considered to be the most important factors responsible for yield gap difference. The increases in yield of Pusa-44 and Pusa Sugandh-5 over the farmers’ practice were 85.3 percent and 54.4 percent, respectively. The technology gap was highest for Pusa-44 (39.6 q ha^-1) followed by Pusa Sugandh-5 (27.4 q ha^-1). The technology index values were almost same for both the improved varieties; Pusa-44 (52.8%) and Pusa Sugandh-5 (47.7%). This gap might be due to various constraints such as soil fertility, availability of low moisture content, sowing time and climatic hazards, etc. In economic point of views, the maximum B: C ratio of 1.65 was registered by Pusa-44 closely followed by Pusa Sugandh-5 (1.44), while it was lowest in local check i.e. Kalonunia.