Physiological studies on the development and the thickening growth of tubers in yams, Dioscorea spp.

本研究分析了光周期和温度条件的变化对山药块茎生长和膨大的影响。在山药植株发育的早期，块茎的生长和膨大开始于日长9小时的30次，而在发育中期，块茎的生长和膨大开始于日长11小时的10次。山药块茎的重量随着暴露次数的增加而增加。虽然山药块茎的生长和扩大不需要低温，但夜间的低温处理促进了已经开始生长的块茎的发育。根据研究结果，日长的缩短似乎是导致山药块茎生长和扩大的主要因素。山药对短日照处理的反应因品种而异，处理的效果取决于块茎的最终大小。在不同处理条件下，块茎成熟期水分含量降低，汁液粘度增加，说明短日照不仅控制块茎开始膨大，而且促进块茎成熟生长。

This investigation was carried out to analyze the effect of changes in the photoperiod and temperature conditions on the initiation of the growth and enlargement of the tubers in yams, Dioscorea spp. .At the early stage of development of the yam plants, the growth and enlargement of the tubers began when the plants were exposed to a 9 hour day length thirty times.At middle stage of development, the growth and enlargement of the tubers started when the plants were exposed to a day length of 11 hours ten times. The weight of tubers increased proportionally to the increase of the number of exposures.Although yam tubers did not require a low temperature for the initiation of growth and enlargement, the development of the tubers in which growth had already been initiated was promoted by the exposure to low temperatures at night.Based on the results obtained, it appeared that the shortening of the day length was the main factor causing the growth and enlargement of tubers in yams.The reaction response of yam to short day treatment varies to some extent among varieties, and the effect of the treatment is in the final size of the tuber at riaturity. Depending upon the treatment, it was observed that while the moisture content of the tuber at maturity decreased, the viscoty of its juice increased.From the above result, it was proved that short day not only controls the commencement of enlargement of the tuber, but also promotes its maturing growth.