落花生の莢実の発育におよぼす結莢圏の土壌温度および土壌水分の影響

抄録

To examine the effects of soil temperature and soil moisture in the podding zone on the pod development of a peanut variety, Chiba-handachi (large seed, semi-erect type), three experiments were carried out under the condition separating the podding zone from that in which the roots were grown. In experiment-I in 1969, the mean soil temperatures in the podding zone were 38.6°C, 30.6°C, 22.9°C and 15.3°C. Experiment-II was performed under four soil moisture conditions, namely 57.3, 40.3, 21.5 and 7.8 percent to the total soil volume. In experiment-III, the effects of the treatments combining high soil temperature (37-39°C) and low soil moisture (6-8 percent) in the podding zone in every 10 days after the peg penetration upon the pod development were exermined. The results obtained were as follows. 1. The beginning time and the rate. of the pod development were affected remarkably by soil temperature in the podding zone. The following relations were observed between the pod development and soil temperature in the podding zone. Optimum soil temperature ; 31 to 33°C Minimum soil temperature; 15 to 17°C Maximum soil temperature; 37 to 39°C 2. It was recognized that the optimum soil moisture content in the podding zone was about 40% to the total soil volume, regardless of the soil moisture content in the rooting zone. When the soil moisture content was lower than 40%, the podding percentage and the thickening growth of the pod were reduced, and when it was higher than 40%, only the thickening growth of the pod was reduced. 3. Considering the rsults obtained in experiment-III, the most critical period in the pod stage was the first 30 days, especially between 20 to 30 days after the peg penetrated into the soil.