Study On The Effect Of Proso Male Sterility Induced By SQ-1

Heterosis is a common phenomenon in nature. The cross between two varieties that have different genetic backgrounds will generate an individual of hyper-parent in yield, quality and resistance. The conventional breeding using heterosis is to use inbred line in maize and male sterility in other crops. Except for the conventional methods by using three-line system or two-line system in male-sterility breeding, the male sterility induced by chemical hybridizing agent is also accepted as a simple and rapid method for heterosis breeding now. There were no reports on the utilization of heterosis in proso and no male sterility line of this crop was found yet. Thus, it is difficult to use heterosis in proso by using conventional genetic method. According to the successful utilization of chemical hybridizing agent in rice, wheat, rape and other crops, we selected the chemical agent SQ-1 that had been used in wheat to induce male sterility of proso and evaluated the induction effect in this study. The main aims are to provide useful information on utilization of male sterility induced by chemical hybridizing agent in common mille, to increase the castration efficiency by using the chemical hybridizing agent, to broaden the cross combination and to accelerate the development of new variety.The split-plot design was used to study the effect of SQ-1 in this study. And the whole experiment was divided into two parts. The first part was to evaluate the effect of SQ-1, in which different growing stages treated by SQ-1 were designed as main plot and different dosages of SQ-1 was as sub plot. The effect of male sterility induced by SQ-1 was evaluated by three indice: male sterile rate, crossing rate and fruit setting rate of natural pollination. The results showed that male sterile rate and crossing rate were both significantly or extremely significantly affected by growing stages, dosages and the interaction between the two factors. These two rates were both over 95% when proso was treated by SQ-1 with dosage of 4.0 kg/hm~2, 5.0 kg/hm~2 during the differentiation of pistil and stamen. And they were also both over 95% when proso was treated by SQ-1 with the dosage of 5.0 kg/hm~2 in the period of primary formation of microspore. The fruit setting rate of natural pollination was not significantly different among varied stages treated by SQ-1, but it was significant affected by dosages and the interaction between stages and dosages. And the fruit setting rate of natural pollination decreased with the dosage being increased. Considering all the three evaluation indices and the cost of production for hybrid seed, the optimal stage treated by SQ-1 in proso was deemed as the differentiation period of pistil and stamen with the optimal dosage was 4.0 kg/hm~2.The second part was to study the effect of interactions between SQ-1 and different genotypes of proso. In this part, different dosages of SQ-1 were designed as main plots and different varieties were as sub plots. The results showed that the male sterility rate was over 95% at dosages of 4.0 kg/hm~2 and 5.0 kg/hm~2, with the variation from 97.9% to 100%. There is no significant effect between SQ-1 and varieties of different genetic background. The male sterility in proso induce by SQ-1 has a wide range of use, and the sterility rate at proper dosage can reach to 100%. The fruit setting rate of natural pollination and artificial saturation pollination both decreased, when the dosage of SQ-1 increased. Different reactions at the same dosage of SQ-1 were found in diverse varieties, and the fruit setting rate of natural pollination fertility and artificial saturation pollination both varied greatly among varieties. According to the observation in the field, SQ-1 has little effect on growth and phenotypes of proso. Although an average of 1.33 cm was decreased in plant height, 2.08 cm was shortened in ear length and 0.7 d was deferred in ear sprouting period, there were no significant differences in plant height, ear length and ear sprouting period between the treated plots and the contrast, this indicated that there was little side effect of SQ-1 on proso.