Growth and yield of the rice plants with varying intensities of water stress during early growth after transplanting
1987
Kwon, Y.W. | Nam, S.Y. | Soh, C.H. | Kwun, S.K. (Seoul National Univ., Suwon (Korea R.). Coll. of Agricultural)
The present study was carried out to determine the period of intermittent irrigation maintaining only wet paddy soil condition not causing significant rice crop loss and to determine the crop loss in the rice plants transplanted in time, but more insufficiently irrigated to suffer in a greater water stress during early growth after transplanting. An indica x japonica variety Nampung and a japonica variety Chucheong was sown on April 27th and transplanted to 1/200 a large plastic pots on June 6th. The rice plants were subjected to varying degrees of water stress during June 9th to July 2nd. The rice growth was reduced in height, tillering and dry matter production even with the water stress of -0.2 bar in the soil moisture for 5 days. The growth inhibition was sensitive in the order of plant height dry matter productiontillering. The growth reduction has shown an exponential decrease with increased water stress and was linearly proportional to the arbitrarily chosen water stress index, [log10(-mean soil water potential) x number of days]. The rice plants have shown very vigorous growth in height, tillering, and dry matter production after the end of water stress resulting in much less difference with the rice plants not stressed in the growth amounts by the heading stage. The longest period of intermittent irrigation to wet the soil not delaying the heading of rice plants significantly was 15 days in both varieties. The period not causing significant yield reduction was 15 days for Nampung and 10 days for Chucheong. Water stress conditions of intermittent irrigation only to wet the soil over 10 days and 5 days followed by natural drying of the soil without irrigation over 10 days reduced the rice yields linearly as water stress index (x) increased, showing Y
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