关键词: 糜子, 光周期, 形态, 幼穗发育

Abstract:

【Objective】 Proso millet is a typical short-day crop that is extremely sensitive to photoperiod changes which limits the geographical adaptation of proso millet varieties. In the present study, the important agronomic traits have been characterized and young panicle development has been observed under both short-day and long-day conditions, which may help better understand reaction mechanism to photoperiod changes and support widely adaptable va riety breeding in proso millet. 【Method】A landrace “Erzigan” was planted in pots under a 18h day light condition, then transferred to a 12h day light condition after 0 day (CK), 10, 15, 20 and 25 days of seedling emergency, each treatment was replicated three times. The main plant characters including heading time, plant height, stem diameter, panicle length, dry panicle weight and dry grain weight per panicle were measured and young panicle development was observed and photographed by using stereo microscope. 【Result】 Plants grown for 25 days under long-day conditions had a plant height of 115.6 cm and a single panicle grain weight of 0.647 g, which was 109.0% and 472.6% higher than the control, respectively. The dry matter accumulation of stem, leaves and ears increased by 416.7%, 142.9% and 412.0%, respectively, comparing with the control. However, the difference in dry matter weight of each organ between the 25d and 20d treatments was not significant. Under the condition of 18 hours day light, the growing point of the stem tip of the proso millet kept in the unstretched period, which meant the plants were at vegetative growth stage without reproductive growing. After 5 days growing under short-day light conditions, the plants began reproductive growth, and the young panicles started to differentiate. The process of young panicle development could be classified into 7 stages including unstretched stage, growing point elongation stage, ear branch differentiation stage, spikelet differentiation stage, floret differentiation stage, pistil and stamen differentiation stage, and pollen grain formation stage. The whole process of young panicle development could last about 15 days before heading, which was not affected by the prolonged light period treatments at early growing stage. 【Conclusion】Artificially prolonging the light period under short day conditions could extend vegetative growth period and was in favor of dry matter accumulation, which can significantly increase the biomass and yielding of proso millet. Short-day conditions promote the transformation of proso millet from vegetative growth to reproductive growth. The whole process of young panicle development could be classified into seven stages, which could last about 15 days before heading and was not affected by all the five treatments at early growing stage.

Key words: proso millet (Panicum Miliaceum L.), photoperiod response, morphological characters, young panicle development