|
Corn is one of the world's first crop heterosis, is also important food crop in China, the total production and yield tops, pivotal to China's grain production. The application of new varieties of maize is the core of maize, maize varieties and their parental inbred lines yield and agronomic traits evolution research has become one of the hot corn genetics and breeding. In this paper, two-factor split-plot experimental design, the main area density, maize varieties and inbred deputy, by analysis of variance, multiple comparisons, correlation and path analysis in Xinjiang typical continental arid climate conditions 1950 to maize varieties in the 2000s and from 1970 to the 2000s, the evolution of maize inbred lines yield and agronomic traits and yield heterosis. The main results are as follows: 1.1950 ~ 2000s varieties of corn production continued to increase. The evolution of the production over years can be divided into three periods. From 1950 to the 1970s, production was significantly improved period from 1970 to the 1990s, the slow growth period, from 1990 to the 2000s very significant increase in period. 2.1950 2000s maize varieties yield genetic gain in the 15000,45000,75000 plants.ha-1 density 0.0732,0.1122,0.1125 ton ha-1.year-1, the average gain of three densities 0.0993 ton.ha- 1.year-1. Density tolerance of maize varieties did not improve. 3.1950 ~ grain weight of maize varieties in the 2000s, rows per ear, kernels per row, ear length, ear diameter, bald tip length was increased; rate of seed, ASI, the BREAKING rate, strain rate decreasing trend; height , ear height, growth period of the evolution of certain rules. Increase in kernels per row is the most important factor to increase in production of maize varieties in the 1950-2000 years. Ear diameter, grain weight, ear length, plant height increases, the growth stages also plays an important role in the improvement of the production. The decline of the rate of seed is the limiting factor of the increase in production of maize varieties in the 1950-2000 years. Corn breeding in the future should pay attention to the kernels per row, grain weight, ear length, plant height may be increased to extend the growing period, and coordinate the relationship with the seed rate. 5.1970 to 2000's production of inbred lines of maize hybrids has been significantly improved. The 15000,45000,75000 plants.ha-1 density yield genetic gain 0.0105,0.0268,0.0348 ton.ha-1.year-1. The average gain of the three densities 0.0240ton.ha-1.year-1. Maize inbred line density tolerance did not improve. 6.1970's 2000 grain weight of maize inbred lines, rows per ear, ear length, ear diameter showed an increasing trend; ASI, bald, long and pointed, strain rate, down the discount rate decreasing trend; kernels per row, the seed rate, plant height, ear height, change certain rules of the growing period. The decrease of 7.ASI from 1970 to the 2000s Maize In the most important factor to improve. Kernels per row, ear diameter increases also plays an important role to increase the yield of inbred lines. Maintain a certain height and the seed rate is high-yield inbred lines. 8 heterosis on yield contribution rate decreases with increasing density. Heterosis With the era of increased the yield contribution rate is getting smaller and smaller, the higher the density of this trend is more obvious.
|