| Research Abstract |
Fertilizer responsiveness with the aim of lavor-saving culture of rice plants was investigated by using root box experiment and filed experiment. The cultivars used in this experiment were Rikuu 132, Senichi, Jyukkoku, Asahi, Futaba, Takenari, Nankin 11, Keicho 2, Raikei, Mitsuyo 23, Calrose 76, Saturn, Rancarolo, Shinriki, Norin 3, Norin 18, Kameji, Suigen 258, Akihikari, Koshihikari and Sasanishiki. Differences in the root system of rice plants at vegetative stage were significant among the cultivars. The angle of the root system of Norin 3 was significantly narrower than that of Rikuu 132, and the space of the root system in the soil of Norin 3 was significantly smaller than that of Rikuu 132. F_1hybrid rice were obtained from the next cross combination, Norin 3 x Mitsuyo 23(F_1-A), Mitsuyo 23 x Norin 3(F_1) , Rikuu 132 x Raikei(F_1-C) and Raike x Rikuu 132(F_1-D), respectively. Heterosis (F_1) effect in the angle of the root systemin the soil were recognized. Diferences in the root system under the conditions of fertilizer application to deeper layer, uniform application of fertilizer to top soil, fertilizer application to lateral and deeper layer, surface application of fertilizer and surface application of fertilizer(deep flood irrigation) were investigated. The angle of the root system in the fertilizer application to deeper layer was significantly smaller than that in the surface application of fertilizer (deeper flood irrigation).
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