Influence of phosphorus on absorption and dynamics of nutrients in rice

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Date
2003
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Department of Agronomy, College of Horticulture, Vellenikkara
Abstract
A pot culture experiment on the "Influence of phosphorus on absorption and dynamics of nutrients in rice" was conducted during December 2002 to April 2003 at the Radiotracer Laboratory, College of Horticulture, Kerala Agricultural University, Vellanikkara. The distribution pattern, content-effectiveness relations of phosphorus on rice productivity in relation to soil types, nutritional levels and the role of organics were investigated in the present study Plant height, tiller number, productive tillers,filled spikelets per panicle,grain and straw yield showed significant increase in kole soil treated with 90:45:45 kgha' NPK along with Pongamia leaves @ 5 tha' (TII). Chlorophyll 'a' and total chlorophyll were highest in Tll having kole soil treated with 90:45:45 kgha' NPK along with Pongamia leaves @5 tha-I at panicle initiation and at 50 per cent flowering. A favourable cell sap pH was also noticed inTll_ TII gave highest plant content of N in both laterite and kole soil. P and K contents were also more in treatments having inorganics with Pongamia. Iron content of rice plants decreased with advancement in the stages of growth. Percent phosphorus derive~ from fertilizer (%Pdff) had highest value at maximum tillering and thereafter it decreased. %Pdff was increased with increasing levels of Phosphor~ls application. When the applications of inorganics with and without organics are compared in laterite and kole soil, application of single super phosphate with organics always gave highest %Pdff than with single super phosphate alone. Laterite soil treated with 90: 67.5: 135 kgha' NPK along with Pongamia leaves @ 5 tha' (Tg) obtained 10.68 % Pdff and the- same treatment in kole soil had 12.96% of %Pdff at harvest. %Pdfs was low at maximum tillering and thereafter increased up to harvest. At maximum tillering, laterite soil treated with 90:45:45 kgha' NPK without organics (T1) gave highest %Pdfs of 93.45% and the kole soil treated with 90:22.5:90 kgha' NPK without organics (T13) gave highest %Pdfs of 93.51 % ,At 50% flowering and at harvest in both soils treated with 90:22.5:90 kgha' ofNPK with or witnout organics recorded highest %Pdfs. Per cent uptake of applied P fertilizer by the plant also had an increasing trend from maximum tillering to harvest. But it was decreasing with respect to increase in levels of phosphorus from 22.5 kghalto 67,5 kgha'. Laterite soil treated with 90:67,5:135 kgha' of NPK along with Pongamia leaves @ 5 tha-I (Ts) registered highest concentration of available P of 16,8 rngkg' followed by the same treatment in kole soil with 16.7 mgkg". A vailable iron content of soil after harvest was more in treatments having Pongamia in laterite soil while it was more with rice straw applied treatments in kole soil The present study indicate that organics-Pongamia and rice straw in conjunction with inorganics enable consistent supply of phosphorus for achieving enhanced grain and straw yield in both late rite and kole soil.Though Pongamia along with inorganics is an ideal fertilizer schedule for rice crop in terms of yield. when the cost of incorporation of Pongamia is considered, rice straw along with inorganics is more profitable and convenient.
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PG
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172273
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