Achievements and main directions of domestic and foreign rice breeding

Abstract

The first green revolution resulted in increased yields for many crops through the introduction of semidwarf forms responsive to high nitrogen inputs. The yield potential of modern inbred and hybrid rice forms reached a plateau at 10–12 t/ha, largely due to an increase in the yield index from 0.3 of traditional cultivars to 0.50–0.55 of modern inbred cultivars and to changes in both biomass and yield. To overcome the rice yield plateau, new plant types (NPTs) characterized by near-perfect morphology, large panicles, increased photosynthesis and lodging resistance were introduced. In breeding for high yield potential, lodging resistance (LR) is always a key target, as it is a yield-limiting factor in irrigated systems with high water and chemical inputs. The stem traits that affect lodging include: length and thickness of internodes, plant height, stem wall thickness, wrapping of internodes by leaf sheaths and leaf thickness. Many studies have noted that high rates of traits characterizing root development largely determine both drought resistance and the effectiveness of mineral nutrition. A wide range of variations in traits characterizing the size of the root system and stem characteristics in domestic rice cultivars was revealed, as well as sources for traits to improve the efficiency of selection. The root length in the studied cultivars was on average 15.96 cm, in eight selected sources it exceeded 20 cm. Its weight exceeded 4 grams in seven samples (average value 2.33 g). Also, the value was twice as high in sources for the trait than on average in the studied cultivars for the trait weight of a stem segment, one and a half times for the trait width of the stem at the base.