The Research On The Character Of The High Outcross-podding Rate Of The Male Parents In The Seed Producing Technology Of Hybrid Soybean

The utilization of heterosis is one of the effective ways to improve crop yields.Highly efficient hybrid soybean (Glycine max (L) Merrill) seed production techniques has achieved remarkable results with the breeding and researching on the photo-thermo-sensitive male sterile soybean material and the cytoplasm nuclear male sterile line of soybean.The research of the high outcrossing rate is the core of hybrid soybean breeding research.The hybrid soybean production,which is by means of insect pollination,is the fundamental guarantee of the industrialization of soybean production.Certain factors such as the characteristics of paternal anther wall,the strength and the law of the pollen germination,the volume of nectar,the concentration of sugar,the population structure of pollinating insects and the intensity of pollination not only directly affect the setting rate of outcrossing of male sterile line but also play an important role in the seed yields.which provide the theoretical basis for the research on the restorer lines and maintainer lines of the hybrid soybean seed production in the future.The experimental materials are five male parental varieties with high or low outcrossing rate widely planted in soybean production.We set about the research on a number of characteristics of five male parental varieties such as the thickness of the anther wall,the time and speed of pollen-releasing and the rate of pollen germination,the volume of nectar,the concentration of sugar,the population structure of pollinating insects and the intensity of pollination by observing the attraction of the male parents to insects and the factors which have impact on the outcrossing rate.We start the research of characteristics above of five male parental varieties.Applying the way of monitoring the pollination and the way of microscope-examing.Carefully analyzed the experimental Results,we can find that conclude as follows:1.The digital monitoring results directly show:insect pollination begins from 10:00 a.m. to 3:00p.m., which reaches the peak from 11:00 a.m. to 1:30 pm; at 11:00 am,the male parental varity with high outcrossing rate has high efficient insect pollination,its valid germination is 4.6 flowers per hour, whereas the valid germination of the male parental varity with low outcrossing rate is 1.46 flowers per hour.The male parental varity with high outcrossing rate attract a large number of pollinating insects which pollinate effectively. While the male parental varity with low outcrossing rate attract a little number of pollinating insects which pollinate lower effectively.2.Through micro-photography and the determination of germination rate of five male parental varieties,we find that at 11:00 am,the pollen germination of male parental varity with low outcrossing rate reaches 16.67%,the average pollen germination rate is 15.01%,whereas the one with high outcrossing rate reaches 1.56%,the average pollen germination rate is 5.81%;the male parental varity with high outcrossing rate can provide more effective pollen to female parents. The male parental varity with high outcrossing rate own the character of thick anther wall and of gradual pollen-releasing and its longer time of pollen sprouting;whereas the male parental varity with low outcrossing rate own the character of thin anther wall and quick pollen-releasing and its shorter time of pollen sprouting.3.The volume of nectar and the concentration of sugar of five male parental varieties were measured.The measuring results directly show that the high outcrossing rate male parental variety has not only more volume of nectar but also higher concentration of sugar.These two features have provided the guarantee for attracting more pollinating insects to improve outcrossing rate. While the volume of nectar is less and the concentration of sugar is lower of low outcrossing rate male parental variety, these are not conducive to attracting more pollinating insects.4.Carefully analyzed the characteristics of the anther walls and of pollen germination and the law of pollinating insects, we can make the following conclusions:The outcrossing rate of some male parental varities are high is that these varities can strongly attract the pollinating insects which pollinate effectively and the anther walls of these varities are thick.Meanwhile,before the peak hours,little pollens are released from anthers,ability of pollen germinating are low,and the rate of pollen germination during the peak period are relatively low,all of which ensure that the father of sterile plants provide more pollen and more effective pollens to female parents.In addition,the insects that pollinate effectively take the ungerminated pollens to the male parents to improve the pollinating rate and consequently the rate of outcrossing are higher. While the male parents with low outcrossing rate have thinner anther wall and before the peak hours the anthers have released much pollens,and there are much pollens have germinated.These male parents attract a small amount of pollinating insects which pollinate neffectively. Consequently,in the peak hours,the male parents provide less ungerminated pollens to the female parents and the germinating rate is relatively low which results in low outcrossing rate.