Studies on the absorbing properites of up-land rice and other crops in different growth periods with automatic recorders.

[摘要] It is primarily important in planning an adequate irrigation program to know how crops absorb water during their growing periods. So the author has studied the water absorbing properties of several crops for some years with automatic recorders designed by himself. The results thus obtained are summarized as follows ; I. Variations of the water amount absorbed by crops during the growth period. As materials the following crops grown under autoirrigated conditions were used ; Annual······up-land rice ; Biennial······barley, vetch ; Perennial······fescue, geranium for perfume, navel orange, Natsudaidai (Citrus Natsudaidai HAYATA), peach. a) The passive absorption in these crops was larger in the water amount than the active. Therefore, the top-size of crops affected remarkably the water absorption. To a certain extent, the water absorption in these crops increased proportionally to their top growth (Fig. 1 and 2.). These results supported that of cane previously reported by the author (1955). Table I shows what a great influence the top-sige has on the water absorption of roots. b) The maximum water absorption period in annual and biennial crops, such as up-land rice, barley and vetch, coincided with their flowering periods (Fig. 1). In perennial crops, such as geranium and fescue, this coincidence was not clear (Fig. 2). In citrus and peach plants, having the maximum absorption period in Augast, there was no relation between the maximum absorption period and the flowering period. c) As the maximum absorption periods in these fruit trees and the fescue plant under them occur together in summer, the summer-cutting of fescue is an important practice for avoiding the scramble for water among those plants. II. OH the relation between the daily variation rate of the water absorption of crops and their growth period. A comparative study of daily variation rate in the water absorption among several crops in different growth periods was undertaken with automatic recorders. a) The periods of maximum daily variation rate in water absorption, in up-land rice, barley and vetch plants, respectively coincided with the period of maximum water absorption, i. e. the flowering period. And the daily variation rate decreased with ripening. At the end of ripening period, the daily variation of water absorption in up-land rice, barley and vetch plants disappeared completely. (Fig. 3 and 4) b) In the perennial crops, such as fescue and geranium, decreasing of daily variation rate with ripening was not observed, the variation being remarkable still in November. (Fig. 5 and 6) From the above mentioned results, it may be assumed that the daily variation rate in water absorption is a good index for root activity. The marked differences in the water absorbing properties among certain crops such as above mentioned should favourably be considered when the planning for watering is designed.

[学科分类] 农业科学（综合）