Vol. 8, Issue 5 (2019)

Author(s):
Divya K, Kalarani MK, Jeyakumar P, Latha KR and Nirmala Kumari A

Abstract:
A pot culture study was conducted to screen seventeen foxtail millet genotypes for drought coupled with heat stress tolerance at anthesis stage under open top chamber. The results revealed that the genotypes TNAU-159 was found to be the tolerant followed by GS – 77 and GS/15/1 based on the physiological and biochemical traits such as photosynthetic rate, chlorophyll fluorescence, relative water content (RWC), chlorophyll stability index (CSI), Nitrate reductase (NR) activity. The combined stress at anthesis stage brought about more severe yield reduction compared to single stress either by drought or heat at anthesis stage. The combined stress at anthesis stage caused reduction in photosynthetic rate, chlorophyll fluorescence (Fv/Fm values), RWC, CSI and NR activity which reduces grain yield. Among the genotypes, TNAU-159 showed its supremacy in recording high drought and heat tolerance with more photosynthetic rate (16.79 μmol CO₂m^-2s^-1), chlorophyll fluorescence Fv/Fm (0.751), RWC (38.07%), CSI (53.95%) and NR activity (55.54 μg NO2 g^-1hr^-1) and 29.41 percent of yield reduction while susceptible genotype GS – 199 recorded lower values of photosynthetic rate (6.59 μmol CO₂m^-2s^-1), chlorophyll fluorescence Fv/Fm values (0.629), RWC (19.15), CSI (10.49) and NR activity of 17.64 μg NO2 g^-1hr^-1 with 93.16 percent of yield reduction during anthesis stage. These physiological and biochemical traits can be used to screen foxtail millet genotypes for drought and heat stress tolerance.