Plant Growth, Macronutrient Concentrations and Agronomic Characters of Rice (Oryza sativa, L.) as Affected by Nitrogen Levels

• Main Authors: Prosper Jean Carlin, 溥加霖
• Other Authors: Shiow-Long Tsai
• Format: Others
• Language: en_US
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/x7em7d

碩士 === 國立屏東科技大學 === 熱帶農業研究所 === 88 === Under field conditions, plant growth and yield response are limited by biotic and abiotic factors. The rapid extension during the last half-century in genetic and molecular biology have made available a wealth of varieties endowing physiological efficiency responses to environmental factors. The combination of varieties and nutrients uptake through management practices remains one of the straight ways to boost yield and increase the productivity. Low fertility, and particularly a deficiency of N, is an important constraint on grain yield in rice and the study of methods for improving N fertilizer efficiency in lowland rice represents a key factor to reduce the steady increasing cost of fertilizer. The objective of this research was to study the response of different nitrogen levels on rice plant growth, agronomic characters, and find whether nitrogen applications could manifest their interactions on nutrient concentrations during the life cycle of rice. Four levels of N (80, 120, 160 and 200 kg N ha-1) were adopted. Two Taiwan improved varieties (Taichung sen 10 and Taisen 2) were compared to two Haiti traditional varieties (Cica-8 and la Crete-a-Pierrot) in combinaison treatments with above N levels. The results showed differences in dry weight due to N levels at 35 DAT. The differences resided in the active growth development of Taichung sen 10 and Taisen 2 during this stage. Tiller number and leaf area index were significantly different at 65 DAT. Cica-8 and la Crete-a-Pierrot preceded Taichung sen 10 and Taisen 2 in tiller number and leaf area index. Phosphorus and potassium concentrations in rice straw decreased with increasing nitrogen levels at 35 DAT, which thereafter increased at 50 and 65 DAT. Protein contents in milled grains increased with increasing nitrogen levels and were the highest in la Crete-a-Pierrot, the lowest in Taisen 2. The oxygen evolution, the soluble protein contents, the flag-leaf chlorophyll contents, the SPAD reading and the total nitrogen concentration sequentially decreased during the first crop (January 2000) from heading to harvest. Panicle dry weight increased until 3 week after heading and decreased thereafter. Partitioning to grains increased sequentially from heading to harvest with Taichung sen 10 partitioned half of the total dry weight to grains and la Crete-a-Pierrot less than half. Partitioning at harvest correlated to chlorophyll contents at 3 week after heading, highly correlated to SPAD reading 3 week after heading, to the total nitrogen concentration at harvest and to the panicle dry weight at harvest, 0.70, 0.76, 0.71 and 0.56, respectively. SPAD reading and chlorophyll contents were linearly regressed from heading to harvest with R2 = 0.867. Positive correlations were found between flag-leaf total N and SPAD, reading total N and oxygen evolution, total N and chlorophyll contents, r = 0.91, 0.72 and 0.95, respectively. Yield decreased with the increase of nitrogen levels during the second crop (July 1999), the first crop revealed yield increase with increasing of nitrogen levels. Yield showed 41% more with Taichung sen 10 in the first crop, which was 128% more with la Crete-a-Pierrot. The difference in cropping seasons was 13% more in la Crete-a-Pierrot for 1000 grains weight, while the percentage of filled grains was 39% and 115% more with Taichung sen 10 and la Crete-a-Pierrot, respectively. Yield correlated with oxygen evolution at 3 week after heading and panicle dry weight at harvest r = 0.61 and 0.59, respectively. Field trial experiments in different ecosystems in Haiti are recommended with Taichung sen 10 for adaptation and the improvement of Haiti traditional varieties (such as Cica-8 and la Crete-a-Pierrot) through the source-sink relationships and the management practices.