| China has the oldest history of growing rice whose output and demand ranks the world. With the agricultural area decreasing and population increasing, improving the yield of rice became a very important measure to insure the food security."There is a place to buy seed but nowhere to buy plants", Seeds with high quality places a very important role to crop growth and food production. As the main indicator of measuring seed quality in the various countries, seed vigor is widely used in seed certification and inspection. Seeds with high vigor not only have high germination rate and germination index, but also show hardy and grow good. As a rice producer, only when we improve the overall quality level can we promote the increase of production radically to solve the food problem.The field experiment of rice seed prodution was conducted in Yong’an Town, Liuyang city of Hunan province in2013.The experiment include the seed production of conventional rice and hybrid rice. Conventional rice has6sowing date and every spike was seperated into the primary branch and the secondary branch. Hybrid rice were cultivated in summer and spring. Seeds were harvested at different time in every treatment, and then measure the moisture contant, weight of1000-seeds,germination rate, germination index and vital index to pinpont the vigor variation of rice seed and the best harvest time.(1) Different sowing date and season have obvious effect on seed vigor.The germination rate, weight of1000-seeds, germination index and vital index of hybrid summer rice seeds are higher than spring rice seed. The germination index and vital index of summer rice seeds are specially higher than spring seeds. The early season rice, middle season rice and late rice of6sowing date showed evident diversity in seed vigor. Among them, early season rice showed the highest germination rate in the first sowing date, middle season rice showed in the third sowing date and late rice showed in the fifth sowing date. The result indicate that the most suitable sowing datie of different variety is various which can promote the acquisition of high vigor seed.(2) Because of grouting timeline and different grouting rate, the seeds of different branch have various plumpness. The early tillerings are superior to the later tillerings. And the high activity duration of the primary branch seeds is longer than the secondary branch seeds. The effect of sowing date on moisture content of the primary branch seeds is greater than the secondary branch seeds. But as for weight of1000-seeds and germination rate, the secondary branch seeds is greater than the primary branch seeds.(3) The develop rules of grain weight, germination rate and seed vigor of different varieties are basically the same which is that seed moisture content gradually reduces, weight of1000-seeds,germination rate, germination index and vital index gradually increases with harvest time delaying. Hybrid rice seeds appears the maximum speed variation before the12th day after pollination. The vital index appeares the maximum value on the15th day after pollination which declines in different degrees after the peak. The germination rate and germination index reach the peak on the12day after pollination and the vital index reach the peak on the18th day after pollination. What is more, the high value duration of germination rate and germination index is longer than vital index. Hybrid rice spend less time to mature than conventional rice.(4) With seed developing and maturing, the morphology of seed changes gradually. The lemma transforms from green to yellow and the color of the ovary changes from green to milk white, as for Xiangwanxian12,it turns into red finally. The time to reach the maximum of the hybrid and conventionnal rice ovary are respectively the9th and15th day after pollination. At the same time, the color of seed deepens as time goes on until the mature period. |
PDF Full Text Request