Abstract
Fertilizer application for rice production has increased significantly in southern China to raise yields, but has led to problems with lodging, quality decline and environmental pollution. Therefore, research on fertilizer-saving cultivation technologies for high-yielding rice is necessary. A two-factor experiment was conducted to evaluate the effects of seedling-addition treatment (SAT) and nitrogen-saving treatment (NST) on yield formation and nitrogen absorption of individual plants and plant groups under the seedling-throwing cultivation system. Numbers of spikelets per panicle and filled grains per panicle of individual plants declined under decreased nitrogen application, but was compensated by substantially increased effective panicles number and total number of glumous flowers under SAT. Under the optimal SAT–NST treatments of 18% less N fertilizer and 32% additional seedlings, yield increased 1.79% and 4.29% compared with that of conventional practice (CK) in 2015 and 2016, respectively. The mature-stage individual-plant biomass under SAT–NST treatments decreased by 27.46% and 20.49% compared with CK in 2015 and 2016, but plant-group biomass did not differ significantly (all >16 t ha−1). Under SAT–NST treatments, effective number of panicles was positively correlated with maximum number of seedlings (r = 0.643) and N absorption amount in the tillering stage (r = 0.901).
Highlights
Rice (Oryza sativa L.) is one of the most important grain crops worldwide, especially in Asia[1]
Under seedling-addition treatment (SAT) (T1 and T2) or nitrogen-saving treatment (NST) (T3 and T4) the grain yield was decreased compared with that of the CK: T1 and T2 yields decreased by 1.30–6.69%, and T3 and T4 yields decreased by 4.42–12.78%
Under the combined SAT–NST treatments the biomass of individual plants declined at the mature stage, but an increase in plant group biomass was achieved through an increase in seedling density, even though N consumption was reduced
Summary
Rice (Oryza sativa L.) is one of the most important grain crops worldwide, especially in Asia[1]. Over the three decades, population growth and decreasing arable land area will pose a severe challenge to rice production in China, which is projected to use 68 million tons of fertilizer by 20302. Zhu et al.[10] observed that a moderate planting density combined with reduced basal application of N fertilizer can lead to rice crops with high yield and high N-use efficiency. The objectives of the present research were to develop high yield potential in the seedling-throwing rice cultivation system by means of an appropriate increase in seedling density and a concomitant decrease in N fertilizer input, and to explore the mechanisms for high yield and N conservation
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