Abstract:

Organic substitution has the potential to enhance the growth and yield of rice. This study could provide important references for the promotion and application of organic alternative fertilization methods in rice production in South China via investigating the effects of different organic substitutions on nutrient uptake and yield of double cropping rice. Six treatments were used for early and late rice plot experiments in field trials, including no fertilization, formula fertilizer, 25% organic substitution, 50% organic substitution, 75% organic substitution and 100% organic substitution. Except for no fertilization treatment, the amount of nitrogen, phosphorus, and potassium used in all other treatments was consistent with the amount of N, P₂O₅ and K₂O being 150, 45.6 and 130.5 kg/hm², respectively. The experimental community was randomly arranged, with 4 replicates for each treatment. Plant samples of early rice were collected for nutrient analysis during the tillering, booting, heading, flowering, filling and maturity stages, and flag leaf and grain samples were collected for nutrient analysis during the filling stage. The changes in SPAD values of flag leaves during the filling stage were measured. The yield and yield components of early and late rice were recorded during the harvest. The research results indicated that formula fertilizer and organic substitution treatment mainly exerted an influence on the uptake of nitrogen nutrients in early rice. The nitrogen content in the aboveground parts of early rice during the tillering and booting stages was significantly higher in the presence of formula fertilizer than that in the presence of organic substitution, and the difference became smaller and smaller after the heading stage. During the filling period of early rice, the SPAD value and nitrogen content of flag leaves increased with the increase of the organic substitution ratio. However, the increase of nitrogen content in grain was not significant. The yield of early rice was the highest with the treatment of formula fertilizer, followed by the 25% organic substitution treatment. The yield of late rice was significantly higher in the presence of various organic substitutions than that in the presence of formula fertilizer, which was confirmed by the increase in the number of grains per panicle and seed setting rate. Organic alternative fertilization might lead to the phenomenon of green and late maturing in early rice, which was not conducive to rice yield and the uptake of nutrients in grains. Organic substitution fertilization was more effective in enhancing rice yield and the uptake of nutrients during late rice cultivation.

Key words: double cropping rice, organic substitution, formula fertilizer, nutrient absorption, yield