Abstract:

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 (r_0.001=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.

Key words: Millet, Male-sterile line, Outcross seed setting percentage, Pistil, Stigma