谷子不育系异交结实率低严重制约着杂交种大面积应用于生产。本研究证明柱头外露程度与异交结实率呈显著正相关（r0.001=0.9597**）。山西省农业科学院经济作物研究所成功选育出谷子光敏雄性不育突变系“81-16”，其不育度为100%，异交结实率达61%。用植物形态解剖学方法证明，“81-16”雌蕊生活力强，柱头完全外露，接受花粉的有效面积大，是其异交结实率高的主要原因。本文还提出应重视母本柱头性状选育，并加强谷子杂交种制种技术研究。
Foxtail millet (Setaria italica Beauv.) is one of the important cereal crops in the arid and semi-arid regions of Northern China, but there is no official report on millet hybrid being used on a large-scale up to the present. One of the main reasons is the very low outcross seed setting percentage of millet male-sterile lines.
In the present research the exsertion score of the stigmas was significantly positively correlated with the outcross seed setting percentage for millet male-sterile lines (r0.001=0.9597**). Economic Crop Research Institute, Shanxi Academy of Agricultural Sciences successfully selected a new photoperiod-sensitive male-sterile millet line “81-16”, with elite stigma characters. Its sterile degree is 100% and outcross seed setting percentage achieves 61%. “Gao 84A” and “Guang 683A/81-16” derived from “81-16” also exhibited desirable stigma characters. We studied the pistil characters of “81-16” with phytomorphology method. Another photoperiod-sensitive male-sterile millet line with regular stigma, “1500”, was used as a check in the study. The results showed that exsertion degree of stigma out of glume and exsertion rate of “81-16” were significantly greater. Stigma characters of “81-16” were more stable than those of “1500” (measured by standard deviation). The pistil of “81-16” was robust with large areas of stigma and lots of pinniform branches. The intervals between branches in “81-16” were same as in “1500”. Pistil lengths of “1500” were similar to those of “81-16”, but area of stigma was only 56% of that of “81-16”. Style of “1500” was longer, but thinner than those of “81-16” and its ovary was smaller. The infirmness of pistils led them difficult to stretch out of glumes at blooming.
By studying pistil characters of male-sterile lines in foxtail millet with phytomorphology method, we could forecast their outcross seed setting percentage. Morphological parameters of pistil reflected the vitality of stigma directly and areas of stigma were positively correlated with outcross seed setting percentages. Some suggestions about increasing the outcross seed setting percentage were raised in this paper that the selection of stigma characteristics for millet male-sterile lines should be emphasized.
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