Foxtail millet, a C4 cereal, is predominantly grown in the arid and semi-arid regions of Asia. Its yield is significantly reduced due to drought and high-temperature stresses. This yield reduction primarily occurs due to a lack of allocation of assimilates produced during photosynthesis to maturing grain when exposed to abiotic stress. To address this issue, a field study was conducted under a rain-out shelter using 24 genotypes, including four checks to assess the genetic variability in photosynthetic rate, grain filling rate, grain filling duration, dry matter translocation, translocation efficiency and contribution rate when drought and heat stress was imposed from peak vegetative to mid grain filling period. The diverse genotypes were classified as tolerant (Group I) and susceptible (Group II) genotypes using the photosynthetic rate. The genotypes with photosynthetic rates of > 29 µmol m-2 sec-1 were grouped into a tolerant category. The genotype ISe-15 was identified as tolerant based on higher values recorded for dry matter translocation (5.11 g plant-1), translocation efficiency (33.80 g plant-1) and contribution rate (27.47 g plant-1) under interactive stress. The genotype IC0479711 was identified as susceptible with low photosynthetic rate (24.2 µmol m-2 sec-1) coupled with less TE (6.78 g plant-1). Thus, the study concluded that foxtail millet genotypes with higher photosynthetic rates coupled with the efficient translocation of assimilates for grain filling under stress can tolerate combined drought and high-temperature stress.
