|Keywords:||稻作;區域性||Issue Date:||Dec-1984||Publisher:||農業試驗所||Related Publication(s):||稻作區域性與期作性低產及增產措施之研究||Start page/Pages:||83-98||Source:||農業試驗所特刊;第16號||Abstract:||
Eighty percent of shadiag for 10 days was performed at successive growth stages of 45 varieties of rice. Heading date, yield and components were investigated. The influence of shading on dry matter production and the concentrations of several major nutrients were also analyzed.
Shading had a definite effect in delaying the heading date of all varieties. The effect was more prominent for japonica varieties or when treatments were executed at early growth stages. Grain yield was severely reduced by shading especially at meiosis stage and rapid grain-filling period. Results showed that number of spikelet per panicle, percent of seed-setting and 1,000-grain-weight were the components responsible for the low grain yield. Although varietal difference existed, shading reduced the yield of 15 Taiwan varieties by 50% or more when compared to the untreated check, suggesting the importance of solar radiation to the normal growth and development of rice plants.
Dry weight per plant was also affected by shading. When treated at the booting stage, culm dry weight was only 65% (japonica rice) or 75% (indica rice) of that of the check plants. For the second crop rice, shading before the the commencement of heading increased N concentration which indicated that the treatment had a more pronounced effect on photosynthesis than on N uptake. The effect was less significant when shading was performed after heading or in the first crop season.
Shading at early growth stages also reduced TNC concentrations in the rice plants. However, the concentrations recovered to that of the check when plants approached heading. Treatments about 0 days before or after heading significantly decreased TNC concentrations in the culm and the subsequent recovery was less obvious. Low solar radiation at meiosis stage could also reduce the contribution of pre-heading storage to the grain yield.
Potassium concentrations decreased in the leaf blade hut increased in the culm for shading treatment performed at any stage of rice development. Shading had little effect on the P concentrations in the leaf blade. However, accumulation of P in the culm was observed. Results suggested that shading could affect the physiolcgical activities of leaf blade and the interconversion and translocation of carbohydrates through altering the mineral nutrition of the rice plants.
|Appears in Collections:||農業工程組|
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