| Planting density is one of the most important agronomical management in rice (Oryza sativa L.). The rice plant-type, canopy structure, population light use efficiency (LUE) and yield and its components are different from planting densities. It is very important for rice variety to achieve maximal population LUE in optimal planting density. In this paper, the dynamics of plant type, LUE and yield of eight rice varieties in four planting density (D1: 30cm×25cm, 0.89 ten thousand individual/mu; D2:30cm×20cm, 1.11 ten thousand individual/mu; D3: 25cm×20cm, 1.33 ten thousand individual/mu; D4: 30cm×15cm, 1.48 ten thousand individual/mu) were investigated, which is to identify the relationship between LUE and planting density. The results are as follows:1. It was significant difference of plant types of eight rice varieties in four planting densities. In tillering stage, plant height of eight rice varieties in lower planting density was higher than that of them in higher planting density, which means that the plant heights of D1 and D2 were higher than that of D3 and D4. After booting stage, the plant height reduced with planting densities increased. In tillering stage, the natural hill plant heights of eight rice varieties in field condition were enhanced with planting densities increaed, except for Xieyou 9308 (erecting plant type). The change of tiller angle of Xieyou 9308 and DI444 was not significant different in the whole growth period in four planting densities, that means the earlier tiller angle was erect and later was semi-scatter. And the dynamics of tiller angle of DI508 was semi-scatter in earlier stage and erect at later in four planting densities. The tiller angles of other five rice varieties were reduced with planting densities increased. The response of canopy width of eight rice varieties to planting densities was significant different, especially in ripening stage. That means the canopy width was reduced with planting densities increased.2. Photosynthesis properties were significant difference among eight rice varieties. The maximal photosynthesis rate, initial quantum efficiency, dark respiration rate and light saturation point in Xieyou 9308(erect plant-type) were lower than in other seven rice varieties, but light compensation point was higher. DI444 (semi-scatter plant-type) and other six rice varieties were opposite. The maximum photosynthesis rate, carboxylation efficiency and CO2 saturation point of DI444 (semi-scatter plant-type) and Xieyou 9308(erect plant-type) were lower than other six rice varieties, but light respiration rate and CO2 compensation point were opposite. The leave photosynthesis rate and soluble sugar content in leave and sheath were reduced with planting densities increased in tillering stage and heading stage.3. Planting density played an important role in dry matter accumulation of rice. The dry biomass per plant of eight rice varieties in four planting densities was reduced with planting densities increased. The dry biomass unit area of eight rice varieties enhanced with planting densities increased in tillering stage. DI444 (semi-scatter plant-type) showed: D1>(D2, D4)>D3. Xieyou 9308 (erect plant-type) maintained: D3>(D2, D4)>D1, and other six rice varieties displayed: D2>(D3, D4)>D1.4. The yield and its components, and population light utilization were different from planting densities. The number of effective panicle per hill and total amount of spikelets of eight rice varieties were enhanced with planting densities increased, but number of grain per panicle, full-filling grain rate and 1000-grains weight were reduced with planting densities increased. The yield of all rice varieties in four planting densities showed: D2>(D1, D3)>D4. The LUE of DI444 (semi-scatter plant-type) was reduced with planting densities increased, but the LUE of xieyou 9308 (erect plant-type) was increased with planting densities increased. The LUE of other six rice varieties maintained: D2>(D1, D3)>D4. |
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