Physiological studies on the sudden wilting of japonica/indica crossed rice varieties in Korea. 1. The effects of plant nutritional status on the occurrence of sudden wilting
1988
Kim, Y.S. (Rural Development Administration, Suwon (Korea R.). Research Bureau)
To identify the physiological phenomena on the sudden wilting of japonica/indica crossed varieties, pot experiment was carried out under the heavy N application with various levels of potassium in Japan. Sudden wilting occurred in both varieties used, Yushin and Milyang 23. The former showed a higher degree than the latter. Sudden wilting occurred into two types, one at early ripening stage and the other at late ripening stage. The former type was found in the field with low potassium supply and the latter seemed to be related to varietal wilting tolerance. By investigating the effective tillering rate and the change of dry weight of each organ at the heading stage, it was inferred that the growth status from young panicle formation stage to heading stage were related to sudden wilting tolerance. Manganese content at heading stage, ratio of Fe/Mn and Fe. Fe/Mn in stem at late ripening stage and K2O/N ratio of stem at harvesting stage were recognized as the specific factors in connection with sudden wilting. Mn content in the sudden wilting rice plant increased already remarkably at heading stage. In relation to root age and absorption characteristics of Mn, the senility of root before heading stage was inferred as the cause of increasing the value of Fe/Mn or Fe. Fe/Mn. The K2O/N ratio of culm at harvesting stage was lower in upper node than lower node in relation to sudden wilting, it was also accorded to the symptoms of sudden wilting proceeded from upper leaf to lower leaf. This phenomenon was different from the usual one that the effect of potassium deficiency was more remarkable in lower node than upper node. All varieties which have potassium deficiency have a high degree of nitrogen content of leaves at heading stage and the K2O/N ratio of each organ was low. Especially, K2O/N ratio is much lower in sheath and culm than leaves
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