Growth Characteristics Of Rice Research Articles

간척지 논 토양의 염 농도가 메탄 배출에 미치는 영향

BACKGROUND: Salt accumulation in coastal reclaimed soil can decrease plant growth and productivity, which could lead to considerable variation of methane(CH4) emission in a rice paddy. The objective of this study was to evaluate the effect of salt concentration on CH4 emission in a coastal reclaimed soil. METHODS AND RESULTS: The effect of salt concentration on CH4 emission and rice growth characteristics was studied by pot test, which packed by reclaimed paddy soils collected from Galsa, Hadong, Gyeongnam province. Electrical conductivity(EC) of each treatment was controlled by 0.98, 2.25, 5.05 and 9.48 dS/m and CH4 emission was characterized a week interval by closed chamber method during rice cultivation. The CH4 emission rate was significantly decreased with increase of salt accumulation, but total CH4 flux in EC 5.50 dS/m treatment was lower than those of EC 9.48 dS/m treatment. It seems because of higher content of water soluble SO4 2- in EC 5.50 dS/m treatment than those of EC 9.48 dS/m treatment. Rice growth and grain yield were significantly decreased with increase of salt accumulation. Soil properties, especially EC and pH were negatively correlated with CH4 flux, while rice growth characteristics like plant height and tiller number show significantly positive correlation with CH4 flux. CONCLUSION(S): Conclusively, salt accumulation significantly decreased CH4 flux in a rice paddy, which could be useful information for evaluating CH4 flux in reclaimed area in Korea.

간척지 논 토양 개량제로서 석고처리가 메탄 배출량 저감에 미치는 영향

BACKGROUND: Gypsum() is known as an ideal amendment to improve soil quality of the reclaimed coastal land. Since gypsum has very high concentration of electron acceptor like , its application might be effective on reducing emission during rice cultivation, but its effect has not been studied well. METHODS AND RESULTS: The effect of gypsum on emission and rice growth characteristics was studied by pot test, which was packed by reclaimed paddy soils collected from Galsa, Hadong, Gyeongnam province. Chemical-grade gypsum was applied in two soils having EC 2.25 and 9.48 dS/m at rates of 0, 0.5, 1.0 and 2.0%(wt/wt). emission was characterized a week interval by closed chamber method during rice cultivation. emission rate was significantly decreased with increasing salt accumulation and gypsum application levels. With increasing gypsum application, dissolved concentration in the leachate water was significantly increased, which might have suppressed production in soil. Total flux was dramatically decreased with increasing gypsum application. In contrast, rice yield was increased with increasing gypsum application and then achieved maximum productivity at 1.0% gypsum application in two soils. CONCLUSION(s): Gypsum is a very good soil amendment to suppress emission in reclaimed coastal paddy soils, and improve rice productivity and soil properties. The optimum application level of gypsum is assumed at ca. 1% to improve soil productivity with reducing effectively emission during rice cultivation.

The screening of mutants and construction of mutant library for Oryza sativa cv. Nipponbare via ethyl methane sulphonate inducing

Following the sequencing of rice genome, the functional analysis of unidentified genes is gaining wide importance. Mutant isolation is one of the effective ways to isolate and clone the target genes and analyze their functions. To find the various mutants in the same genetic background, seeds of Oryza sativa cv. Nipponbare were treated with ethyl methane sulphonate (EMS). A total of 1056 mutants were screened for five categories in M2 generation with the seedling frequency of 26.29‰ at three-leaf stage, but only 264 mutants were verified in M3 generation with a frequency of 6.57‰. Among the mutants verified in M3 generation, the frequency of leaf mutation was the highest (2.22‰), followed by seedling height (1.74‰) and the abiotic stress tolerance mutant (1.47‰). Nineteen characteristic mutations, including a big group of abiotic stress tolerant mutants such as herbicide resistant, salt tolerant and drought tolerant were identified at this stage. By observation of rice growth characteristics at different developmental stages, another 220 mutants have been isolated and verified in the M3 generation with the mutant frequency of 53.9‰ covering about 28 mutant traits. Among those identified, the highest frequencies were obtained for appearance of brown rice mutant with 18.37‰, followed by panicle mutant with 13.47‰, and grain mutants with 9.06‰. All the mutants screened above were suitable for gene function analysis and for utilization in agronomy.

Rice yield reduction by chamber enclosure: a possible effect on enhancing methane production

Major rice growth characteristics and grain yield were compared between inside and outside of a chamber coverage area after a seasonal CH4 and N2O flux measurement using a closed chamber technique. Results show that only grain yield was significantly (P 0.05) in plant height, total straw weight, spike length, and average grain weight. Temperature increase during the gas flux measurement was likely the major cause for the observed grain yield decrease by sterilizing rice reproductive organs. Methane flux rates from rice fields were likely overestimated by using closed chamber technique because decreasing grain yield by chamber enclosure may result in more plant photosynthesis products released into soils to enhance CH4 production. Analyzing CH4 and CO2 emission ratio from the rice field, after cutting the above-water part of rice plants, indicated that CH4–C emission accounted for approximately 13% of the total CO2 and CH4–C emission during the major rice growing season.

水稲代かき同時打込み点播機の作業性能および栽培特性

Performance test of the seed-shooting seeder of rice was carried out in some soil conditions of paddy field and the growth characteristics of rice were investigated.The results were as follows:1) Soil viscosity and seeds velocity just shot onto soil surface seemed to influence the germination depth of rice. The depth was 5-20mm in the case that seeds were shot into submerged soil (viscosity: 50-150dPa·s) of a paddy field.2) The form dimensions of the hill-seeded spot (ellipse in shape) which was obtained in a paddy field was 6-10cm (longer diameter) and 3-5cm (shorter one).3) Work efficiency of the seeder was 0.4ha/h (working width=2.4m). It was generally equal to one of rotary type transplanter of rice.4) Lodging tolerance of the hill-seeded rice was nearly equal to one of the transplanted rice and was superior to one of the broadcasted rice.5) Yield of the hill-seeded rice was about 10% inferior to one of the transplanted rice.

Effects of Elevated CO2 Concentration and High Temperature on Growth and Yield of Rice. I. The effect on development, dry matter production and some growth characteristics.

Phenological development, biomass production and the related growth characteristics of rice (cv Akihikari) in canopy were measured over the entire growth period under different CO2 concentrations and air temperature regimes in temperature gradient chambers (TGCs), in order to clarify the effects of anticipated global climate change on rice production. The TGC is a plastic tunnel with the dimensions of 26m in length, 2.05m in width and 1.7m in height in which air was ventilated at varying rates to created a 4°C temperature gradient along its longitudinal axis. Two TGCs were used for this experiment; one was kept at ambient CO2(c350 μLL-1) concentration and the other at 690 μLL-l throughout the entire growth period. CO2×temperature treatmets were applied to potted rice plants displaced in TGC at the density of 20 hills m-2 in 1991, and on transplanted plants on soil bed in TGC at 25 hills m-2 in 1992. In both years, a sufficient amount of nutrition was applied in split. The nearly doubled CO2 concentration (690 μLL-1) accelerated phenological development of rice toward heading with more pronounced effects at higher temperatures. The number of days to heading of elevated CO2 plants at 30°C was 11% less than that of ambient CO2 plants. The elevated CO2 concentration remarkably promoted both total and productive tiller numbers, whereas it gave a negligibly small effect on plant height. Also, the clevated CO2 concentration gave minor effects on leaf area index except at the initial growth stage, coinciding with the previous workers' results. The elevated CO2 concentration markedly promoted crop dry matter production, on which temperature appeared to give negligibly small effects. The relative enhancement rate by the doubled CO2 on crop dry weight at maturity was estimated to be 24% as average over the entire temperature range (26∼30°C) in both years. The insensitive temperature response in the enhancement rate was contrary to previous workers' results. This is considered to be due to previous workers' results being based on largely isolated plants where radiation might less limit the growth than in the present experiment in the canopy condition.