• Applied Biological Chemistry
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• v.17 no.1
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• pp.1-30
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• 1974

Present study was undertaken to elucidate the relationship between uptake of nutrients and photosynthetic activities, and the translocation of several mineral nutrients in rice plants which were grown under different cultural conditions, utilizing radioactive tracer technique. Particular emphasis was placed on the analysis of patterns of nutrient uptake, the relationship between nutritional conditions and yield components. For this, rice plants grown on either low or high yielding fields at different growth stage were subjected to this study. The results are summarized as follows; 1. Varietal difference was observed in the uptake of potassium and phosphorus. Kusabue and Jinheung had good capacity but Paldal had rather poor capacity for the uptake of the both nutrients. 2. For rice plants, a high positive correlation was found between the oxidation of alpha plaus-naphthylamine by root and uptake of phosphorus. 3. Carbon assimilation rate repended on rice varieties. It was high in Noindo, Gutaenajuok #3 Suweon #82 and Jinheung but low in Taegujo, Kwanok, Yugu #132 etc. 4. Heavy application of nitrogen increased carbon assimilation in rice plants but this also depressed translocation of certain carbohydrates to ears. 5. Carbon assimilation wan greatly hampered in rice plants deficient in magnesium, phosphorus or potassium. 6. Total dry matter after ear formation stage, was much higher in rice plants grown in high yielding fields than those grown in low yielding fields. 7. Leaf area index(LAI) reached maximum at heading stage and decreased thereafter in high yielding fields. But in low yielding fields, it reached maximum before heading and sharply decreased thereafter due to early senescence of lower leaves. 8. In general, light transmission ratio (LTR) of leaves was higher in the early growth stage and lower in later stages. Higher ratio of LTR to leaf area index, was found in the rice grown in high yielding fields than those in low yielding fields. 9. Net photosynthetic activity decreased with the increase in leaf area index but was higher in high yielding fields than in low yielding fields. 10. After the ear formation stage, nitrogen, potassium and silicon as weil as $K_2O/N$ in straw were higher in high yielding fields than those in low yielding fields. 11. Nitrogen, phosphorus, potassium and magnesium taken up by rice plants in low yielding fields before heading stage were readily translocated to ears than those in high yielding fields. This suggests greater redistribution of nutrients in straw occurs due to lower uptake, in later growth stages, by rice plants grown in low yielding fields and hence results in early senescence due to nutrient deprivation. 12. In the high yielding fields nitrogen uptake by rice was slow but continuous throughout the life of the plants resulting in a large uptake even after heading. But, in low yielding fields the uptake was fast before heading and slow after heading. 13. A high positive correlation was found between the contents of nitrogen and potassium in the straw at heading stage and grain yield. Positive correlation was also found to hold between the contents of potassium, silicon, $K_2O/N$, $SiO_2/N$ in the straw at harvesting stage, and grain yield. 14. Carbon assimilation was greately hampered in rice plants deficient in magensium, phosphorus or potassium. 15. Uptake of nitrogen, phosphorus, potassium, silicon and manganese by rice was considerably higher in high yielding fields and reached maximum at ear formation stage. 16. In rice, a high positive correlation was discovered between total uptake of nitrogen, phosphorus, potassium, calcium, magnesium, silicon, manganese at harvesting stage and grain yield. 17. In rice, a high positive correlation was found between the total uptake of nitrogen, phosphorus, potassium, calcium, magnesium, silicon at harvesting stage, and number of spikelets per $3.3\;m^2$. In addition, a correlation was found between the total uptake of nitrogen and potassium and number of panicles per hill.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.407-428
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• 1991

The eastern coastal area having variability of climate is located within Taebaek mountain range and the east coast of Korea. It is therefore ease to cause the wind damages in paddy field during rice growing season. The wind damages to rice plant in this area were mainly caused by the Fohn wind (dry and hot wind) blowing over the Taebaek mountain range and the cold humid wind from the coast. The dry wind cause such as the white head, broken leaves, cut-leaves, dried leaves, shattering of grain, glume discolouration and lodging, On the other hand the cold humid wind derived from Ootsuku air mass in summer cause such symptom as the poor rice growth, degeneration of rachis brenches and poor ripening. To minimize the wind damages and utilize as a preparatory data for wind injury of rice in future, several experiments such as the selection of wind resistant variety to wind damage, determination of optimum transplanting date, improvement of fertilizer application methods, improvement of soils and effect of wind break net were carried out for 8 years from 1982 to 1989 in the eastern coastal area. The results obtained are summarized as follows. 1. According to available statisical data from Korean meteorological services (1954-1989) it is apperent that cold humid winds frequently cause damage to rice fields from August 10th to September 10th, it is therefore advisable to plan rice cultivation in such a way that the heading date should not be later than August 10th. 2. During the rice production season, two winds cause severe damage to the rice fields in eastern coastal area of Korea. One is the Fohn winds blowing over the Taebaek mountain range and the other is the cold humid wind form the coast. The frequency of occurrence of each wind was 25%. 3. To avoid damage caused by typhoon winds three different varieties of rice were planted at various areas. 4. In the eastern coastal area of Korea, the optimum ripening temperature for rice was about 22.2$^{\circ}C$ and the optimum heading date wad August 10th. The optimum transplanting time for the earily maturity variety was June 10th., medium maturity variety was May 20th and that of late maturity was May 10th by means of growing days degree (GDD) from transplanting date to heading date. 5.38% of this coastal area is sandy loamy soil while 28% is high humus soil. These soil types are very poor for rice cultivation. In this coastal area, the water table is high, the drainage is poor and the water temperature is low. The low water temperature makes it difficult for urea to dissolve, as a result rice growth was delayed, and the rice plant became sterile. But over application of urea resulted in blast disease in rice plants. It is therefore advise that Ammonium sulphate is used in this area instead of urea. 6. The low temperature of the soil inhibits activities of microorganism for phosphorus utilization so the rice plant could not easily absorb the phosphorus in the soil. Therefore phosphorus should be applied in splits from transplanting to panicle initiation rather than based application. 7. Wind damage was severe in the sandy loamy soil as compared to clay soils. With the application of silicate. compost and soil from mointain area. the sand loamy soil was improved for rice grain colour and ripening. 8. The use of wind break nets created a mocro-climate such as increased air. soil and water temperature as well as the reduction of wind velocity by 30%. This hastened rice growth, reduced white head and glume discolouration. improved rice quality and increased yield. 9. Two meter high wind break net was used around the rice experimental fields and the top of it. The material was polyethylene sheets. The optimum spacing was 0.5Cm x 0.5Cm. and that of setting up the wind break net was before panicle initiation. With this set up, the field was avoided off th cold humid wind and the Fohn. The yield in the treatment was 20% higher than the control. 10. After typhoon, paddy field was irrigated deeply and water was sprayed to reduce white head, glume discolouration, so rice yield was increased because of increasing ripening ratio and 1, 000 grain weight.