eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2017-03-25 14 1 209 217 10.13005/bbra/2437 21998 article P. I. Kostylev 1 A. V. Alabushev 1 E. V. Krasnova 1 A. A. Redkin 1 L. M. Kostyle 2 All-Russian Research Institute of Grain Crops after I.G.Kalinenko, Russia, Zernograd, Nauchnyi gorodok, 3. Azov-Blacksea Engineering Institute of the Don State Agricultural University, Russia, Zernograd, Lenin street, 21. Normally, F₁ hybrids between subspecies japonica and indica demonstrate various degrees of sterility. Previous research has shown that certain types of indica do have compatibility when crossed with japonica varieties, which causes a higher fertility in F₁ hybrids. In the light of the above, we studied several indicators affecting grain crop yield in F₁ hybrids between japonica and indica. A field experiment was done to study hybrid heterosis of plant height, panicle length, the number of spikelets and well-filled grain in a panicle, spikelet fertility, length, width and weight of grains, in order to find a combination with high grain yield and investigate correlations between grain weight per panicle and certain valuable agronomic traits. Average heterosis of plant height and number of spikelets per panicle was positive. Some of the hybrids demonstrated positive heterosis of the number of well-filled grains in a panicle, of the weight of grain from one panicle, of the size and weight of grains; on the average, however, heterosis of these traits was negative.  Among other crop yield components, an increase in the number of spikelets and grains per panicle contributed to an increase in the weight of grains from one panicle in hybrids. There exists significantly strong positive correlation between crop yield in one panicle and spikelet fertility and a weakly positive one - with the plant height and panicle length. A higher yield from one panicle in F₁ crosses was related to an increase in the number of spikelets in it, whereas their low fertility was a limitation on yield potential. https://www.biotech-asia.org/vol14no1/a-study-of-f1-rice-hybrids-from-crossing-two-subspecies-indica-and-japonica-in-south-russias-climate/ crop yield; fertility; hybrids;  heterosis Rice; sub-species japonica and indica;