水稻"三控"施肥技术的生物学基础

水稻"三控"施肥技术是一项高产稳产、省肥省药、节本增效的施肥新技术,其主要生物学基础是:(1)氮肥利用率与总施氮量、基蘖肥施氮量呈显著负相关,穗粒肥的氮肥利用率高于基肥,后者又高于分蘖肥,因此应控制总施氮量和基蘖肥施氮量,实行氮肥后移;(2)分蘖速率由群体已有茎蘖数、叶片含氮量和叶面积指数共同决定,提高成穗率要从控制最高苗数和提高已有分蘖成活率两方而人手,群体成穗率与干物质积累动态密切相关,适当控制幼穗分化前生长速率和提高幼穗分化后生长速率,是提高群体成穗率的重要物质基础;(3)水稻纹枯病的发生主要由气候条件和植株群体指标决定,纹枯病病情指数与最高茎蘖数、抽穗期叶面积指数和叶绿素含量呈正相关,而与抽穗期群体透光率呈负相关,为通过群体调控减少纹枯病的发生提供了依据.

Some principles for the"Three Controls"nutrient management technology for irrigated rice

The"three controls" nutrient management(TCNM) is a new technology with which high and stable yield can be achieved with less fertilizer and pesticide input.Discussed in this paper are some principles of this new technology.(1)Fertilizer-N use efficiency(NUE) is negatively correlated with total N input and N rate at basal and/or at tillering stage.The NUE is greater when fertilizer-N is applied during panicle development and at heading than that applied as basal or at tillering.Therefore the amount of N applied as basal and/or at tillering should be reduced.(2)Tillering rate is determined quantitatively by the existing tiller number,leaf N concentration,and leaf area index.Higher productive tiller percentage(PTP) can be achieved either by reducing maximum tiller number or preventing existing tillers from death.The PTP is closely related with dry matter accumulation dynamics.Limiting dry matter production before panicle initiation is important for reducing maximum tiller number and hence achieving high PTP.(3) The occurrence and development of sheath blight is determined both by climatic factors and canopy indices,i.e.the maximum tiller number,leaf area index,leaf chlorophyll content,and light transmission ratio of the canopy at heading.Thus the disease incidence can be reduced through improved crop management.