Studies on the mechanism of single basal application of controlled- release fertilizers for increasing yields of rice (Oryza sativa L.)

صينى. 探讨水稻一次性施用控释肥增产机理。采用盆栽试验和网箱试验，研究了3种控释肥对土壤速效氮含量、水稻根系生长发育、后期衰老和抗倒伏能力的影响。与专用肥分次施用处理比较，一次性施用等养分的植物素包膜控释肥（CRF1）、高分子材料包膜尿素复混肥（CRF3）显著提高了土壤速效氮含量，移栽30 d以后平均含量分别高出12.0%和147.9%；明显促进根系生长，根系数量大、分布深广、活力增强；灌浆后期旗叶叶绿素含量分别提高9.5%和15.5%，可溶性蛋白提高89.7%和108.0%，CAT酶活性明显增加；茎基部粗壮，根深指数大，茎根比降低。即使施用低钾含量的磷酸铵镁包膜控释肥CRF2也能促进根系发育、提高根系活力、增强旗叶生理功能。水稻一次性施用控释肥增产主要机理表现为显著提高了氮素供应水平，明显促进水稻根系生长发育，强化根系吸收养分能力，延缓后期衰老速度，并显著改善了水稻抗倒伏能力。

إنجليزي. This paper explores the single basal application mechanism of controlled-release fertilizers for increasing rice (Oryza Sativa L.) yields. Pot and cylinder trials were carried out from 2002 to 2005 to study the influences of single basal applications of 3 controlled-release fertilizers. The study looked at the changes in concentration of soil available N, root development, consenescence and lodging resistance at late growth stages. Results showed that at 30 days after fertilization, single basal application of controlled-release fertilizers coated with vegetal-substance (CRF1) and polymer materials (CRF3) increased the soil’s available N to 12.0% and 147.9%, respectively. This was compared to rice-specific fertilizer (RSF1). Splitting. Treatments of the two CRFs obviously benefited the development of root system, resulting in greater rice root weights with extensive distribution and higher root activity. In addition, the two CRF treatments, in comparison to the RSF1 treatment, enhanced chlorophyll contents of the flag leaves to 9.5% and 15.5%, and soluble protein to 89.7% and 108.0% respectively. Application of the two CRFs also made the base of rice stems strong and large, declined the proportion of shoot to root, increased root depth index. Though relatively lower in K rate, single basal application of the CRF3 coated with NH4MgPO4 may also promote the development of root system, enhanced root activity and some physiological functions of flag leaves. From these results, we concluded that major mechanisms of yield-increase by single basal application of the CRFs should be attributed to greater soil available N supply, superior development of root systems, better nutrient absorption capacity, slower senescence, and enhancement of lodging resistance at late stages.