Improving the cultivated rice Sakha104 (Oryza sativa L.) using gene pools of some relative wild species.

Background: Rice (Oryza sativa L.) is considered a staple food for one-half of the world's population. The yield of rice must increase to keep up with the world's population growth. Blast disease (caused by Magnaporthe oryzae) is biotic stress that threatens rice production and can result in yield losses up to 70%.

Methods: The present research attempted to widen the genetic base of Egyptian cultivated rice Sakha 104 (Oryza sativa), using gene pools from certain relative wild ancestors, in order to cope with blast infection and grain yield. Crossing Sakha 104 × O. glaberrima and Sakha 104 × O. glumaepatula resulted in selecting 20 genotypes. The produced genotypes and the Egyptian cultivar Sakha 104 were assessed for days to heading (HD), plant height (PH), number of tillers/plant (NTP), panicle weight (PW), 1,000-grain weight (TGW), grain yield/plant (GYP), spikelet fertility (SF), blast reaction (BR), hulling percentage (HP), milling percentage (MP), head rice (HR), and amylose content (AC).

Results: Line AS-AF L3 had the earliest heading date, whereas AS-AF L6 revealed the lowest and the best values in plant height. In addition, line AS-AM L9 generated the most tillers/plant and the heaviest panicle weight. For TGW, AS-AM L3 showed the uppermost value, while AS-AM L4 recorded the highest percentage in spikelet fertility and high productivity of grain yield/plant. Furthermore, all assessed genotypes presented a unity (the value of 1) across the two seasons of evaluation in blast reaction. Grain quality criteria such as hulling, milling percentages and head rice assigned to AS-AF L10 and AS-AM L3, whereas AS-AF L2 possessed the lowest values in amylose content. Moreover, genetic variance (GV), phenotypic variance (PV), genotypic and phenotypic coefficient variations (GCV and PCV) were estimated for all traits with higher PV and PCV than GV and GCV, respectively. Heritability in broad sense (h2b%) disclosed high heritability values for heading date (0.85), plant height (0.925), grain yield/plant (0.95), 1,000 grains weight (0.92), blast reaction (0.935), head rice (0.97) and amylose content (0.90), reflecting strong genetic control of these traits. Eventually, broadening the genetic background of Sakha 104 cultivar against blast infection will minimize its impact and enhance the food security in Egypt.