Plant Growth and Fate of Nitrogen in Mixed Cropping, Intercropping and Crop Rotation : II. Nitrogen content of wheat in association with pea or broad bean

[摘要] Wheat were grown alone or in association with pea (Pisum sativum L.) or broad bean (Vicia faba L.) under several treatment conditions of nitrogen application, temperature and clipping in nitrogen-poor soil. The results are summarized as follows. 1. Without nitrogen fertilizer and with nitrogen 1 kg/10 a, top dry weight and nitrogen content of wheat in association with pea were the same as those grown alone on the 60th and the 70th day after sowing, but were remarkably larger on the 85th day when tops of the pea died and almost all the root nodules sloughed off (Figs. 1, 2, 3 and 4). With nitrogen 8 kg/10 a, however, they were less than those grown alone 60, 70 and 85 days after sowing. 2. Wheat grown in association with broad bean yielded smaller top dry weight and nitrogen than those grown alone till the 83rd day after planting at 10°, 15°, 20°and 25°C (Figs. 5 and 6). In the early stage of anthesis of broad bean 4 months after planting, the wheat at 15°, 20° and 25°C yielded more dry weight and nitrogen, being largest at 20°C where broad bean growth was most marked on the 53rd and 83rd day (Figs. 8 and 9). Four months after planting, acetylene reduction activity declined markedly and some of the root nodules sloughed off (Fig. 9). At 10°C, top dry weight and nitrogen content of wheat did not increase by association with broad bean. 3. Clipping the tops of broad bean plants in soil culture increased top dry weight and nitrogen content of associated wheat at 15°, 20° and 25°C. These increase were observed 30 days after clipping at 20° and 25°C and after 66 days at 15OC (Figs. 5 and 6). Broad bean grown in gravel culture containing no nitrogen fertilizer increased inorganic nitrogen in the culture solution after clipping their tops. The amount of nitrogen increased markedly at 20°C than at 10°C (Table 2). It is found from these results that the increase of nitrogen content of wheat by association with these two legumes is observed 3 to 4 months after sowing or planting and also that this increase is promoted by the favorable conditions for nodulation and nitrogen fixation, such as nitrogen-poor soil and appropriate temperature.

[学科分类] 农业科学（综合）