Abstract

                                High temperature stress is a major environmental factor that affects cropgrowth, development and yield, it especially limits rice yield. Hence, anexperiment was conducted to study the impact of high temperature onmorpho-physiological parameters and yield of rice genotypes. Ten ricegenotypes were used in this study viz., N22, ADT 36, ADT 37, ADT 43, ADT45, CO 51, ASD 16, MDU 6, TPS 5 and Anna (R) 4. The study was carriedout at OTC (Open Top Chamber) with the treatments of ambient, ambient+2O C and ambient +4O C. Stress was imposed from anthesis to early grainfilling period. Observations on plant height, the number of tillers, leaf area,SPAD (Chlorophyll index) and chlorophyll stability index (CSI) were done afterthe stress imposement and grain yield was calculated after harvest. Resultsrevealed that, the significant changes were observed in morpho-physiologicaltraits and grain yield of rice genotypes among the treatments and with thegenotypes. N22 (10% and 19%) and Anna (R) 4 (12% and 22%) recordedless reduction of grain yield in ambient +2O C and ambient +4O C comparedwith ambient, due to less reduction of total chlorophyll content, SPAD values,leaf area and increased plant height. These parameters resulted in higherbiomass which indirectly contributed to higher grain yield in N22 and Anna(R) 4 under high temperature.

Key words : Rice; High temperature; Leaf area; Chlorophyll index; Total chlorophyll content