| Objective: With the development of maize production mechanization, single grain sowing technology has gradually become a trend. Large foreign seed companies enters the domestic market with its higher vigor seed, which brings China’s seed industry tremendous pressure. So seed production with higher vigor is a basic requirement to meet the challenges. Low temperature in seed harvest period in Xinjiang,and early frost limits the seed harvest time, and affects the quality of maize seeds. In this study, the relationship of maize seed maturity and seed vigor was studied with 3 types 6 different maize hybrid varieties, the research would be helpful to determine the optimal harvest time for the production of maize seed with higher vigor for maize seed companies.Method: Seeds of six maize hybrid cultivars(Xinyu 35, Xinyu 54, Xinyu 29, Xinyu 41, Zhengdan958 and Xianyu 335) were hybreded and collected every 3 d after pollination 30 d. Seed fresh weight, seed dry weight, and seed moisture content were measured, and the time of black layer appearance was recorded.The relationship between seed maturity and vitality of the six cultivars with 3 different maturity types was determined basing on the growth characteristics, stress tests indexes and physiological or biochemical parameters.The main results and conclusions:1. The seed fresh weights of the early maturing varieties(i.e., Xinyu 35 and Xinyu 41) reached a maximum on the 39 th d after pollination. The seed fresh weight of the other four cultivars reached maxima on the 45 th to 51 th d d after pollination. And seed moisture contents decreased linearly after pollination,the dehydration rates ranks in the decreasing order as follows: Xinyu 35 > Xinyu 29 > Xinyu 54 > Xinyu 41 >Zhengdan 958 > Xianyu 335. For the early maturing varieties, the seed black layer appeared on the 48 th d after pollination, and their seed dry weight reached the maximum on the 45 th to 48 th d after pollination. For the mid-maturing varieties, the black layer appears on the 51 th d after pollination, dry seed weight reaches the maximumon the 48 th d after pollination. The dry seed weight of the late maturing varieties Xianyu 335 and Zhengdan 95 reaches the maximum on the 54 th d and 63 th d after pollination, respectively,and theirgrain black layer appears on the 54 th d and 60 th d after pollination.2. With the continue of maize seeds maturity, the germination energy, germination rate, germination index and vigor index increase, but they keep stable after reaching a higher level, while the difference between the different maturity seeds was significant. For the early maturing varieties, the germination energy and germination rate reached the maximum on the 42 th to 48 th d after pollination. For the mid-maturing varieties, the germination energy and germination rate reached the maximum on the 51 th d after pollination. And the late maturing varieties, germination potential reached the maximum on the 54 th to57th d after pollination, while the germination rate reached the maximum on the 48 th and 57 th d after pollination. The germination index and vigor index for the early maturing varieties reached the maximum on the 45 th to 48 th d after pollination. Xinyu 41 reached maxima at 51 th d after pollination, and the maturingvarieties reached maxima 54 th to 60 th d after pollination.3. Germination rate and the germination rate at 10 oC, for the early maturing varieties reached the maximum on the 45 th to 48 th d after pollination, which were about 90%. For the mid-maturing varieties, the germination rate reached the maximum on the 54 th d after pollination, which was about 85%. And the germination rate for the late maturing varieties reached the maximum, 90%, on 57 th d after pollination. The germination rate of the agingseedsfor the early maturing varieties reached the maximum, more than 95%,on the 45 th to 48 th d after pollination, and it for mid-maturing varieties was 87%, the maximum, on the 54 th d after pollination. The aging germination rate of reached the highest percent at. The germination rate of the aging seeds for the late-maturing varieties, Xianyu 335 and Zhengdan 958, reached the maximum on the60 th d and 57 th d after pollination, both of them were about 90%. No significant positive correlation was showed beteen all these indicatorsand seed maturity.4. The relative conductivity of the early maturing varieties(i.e., Xinyu 29 and Xinyu 35) reached the minimum on the 54 th d after pollination, however, the lowest relative conductivity of seeds for Xinyu 54 was found on the 63 th d after pollination, Xinyu 41 reached minima 48 th d after pollination, the maturing varieties reached minima 57 to 60 d after pollination. The TTCH content(optical density value) for early maturing varieties reached the maximum on the 45 th to 48 th d after pollination, for mid-maturing varieties reached the maximum on the 48 th d after pollination, and for the late maturing varieties,the maximum appeared on the 54 th d after pollination. So they the best time for the harvest for high vigor seeds production.5. The seedling emergence rate in field for the early maturing varieties reached the maximum on the42 th to 45 th d after pollination,which were about 89% to 94%, and there were no significant difference of the seeds harvested after the 45 th d after polinationseed harvest field emergence was not. The seedling emergence rate in field for the mid-maturing, was about 92.3%, the maximum on the 45 th d after pollination,and the maximum seedling emergence rate in field appeared on the 57 th d after pollination. So the seeds harvested during these periods, can keep the highest seed vigor, and decearse the risk of early frost harm..In summary, for the early maturing varieties, the seeds on the 45 th to 48 th d after pollination, and its water content 29.1% to 34.3%, the 3th to 6th d before black layer appearing, can get higher vigor seed. For the late-maturing varieties, on the 48 th to 51 th d after pollination, the water content, 35.4% to 35.9%, 3 to 6d before black layer appearing, can get higher vigor seed. For the late maturing varieties, on the 54 th to 57 th d after pollination, the water content of 34.7% to 38.1%, 3 to 6 d before black layer appearing, can get high vigor seed. These conclusion will provide some thoery technical support for higher vigor seed corn production to maize seed production company... |
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