Performance of promising rice varieties under ambient and elevated temperature regimes

Open top chamber system was designed for undertaking research into rice crop response to increased temperature during rainy season at Regional Agricultural Research Station (RARS), Khajura, Banke in 2018. With the objective of determining the efficacy of the chamber system and to generate possible differences in climate which could alter plant response between ambient and chamber system, 5 different rice varieties (Radha-4, Sukhkhadhan-3, Sukhkhadhan-2, IR83383-G-B-141-1 and IR87751-20-4-4-2) with three temperature conditions were used: ambient condition, open top chamber with 1.2m height enclosed from base with plastic sheet and open top chamber with 1.5m height enclosed from base with plastic sheet. With 3.1°c higher temperature Sukhkhadhan-2 significantly (p value= 0.0199) produced higher grain yield 4.33 t/ha under chamber condition in contrast to open field (2.93 t/ha) as well as significantly (p value=0.0175) higher biomass yield 13.62 t/ha under elevated temperature. Also, Sukhkhadhan-2 significantly (p value=0.0012) attained maximum height (86.99 cm) under chamber condition compared to open field (73.06 cm) during harvest. Statistical analysis showed no significant difference for number of tillers per hill during maturity stage. Significantly sukhkhadhan-3 (p value=0.02994) showed longer panicle length 25.7cm under chamber than normal field condition (23.74 cm). In addition, Radha- 4 significantly (p value=0.03823) produced more filled grains per panicle (169) under chamber conditions than ambient condition (112). The consideration of crop variety is a good adoption measure to minimize incidence of elevated temperature in farming system.