Morphological and molecular evaluation of Turkish rice (Oryza sativa L.) landraces

Genetic Resources and Crop Evolution - This study was carried out to evaluate Turkish rice landraces, in 2016 and 2017. Twenty-nine morphological traits were used for morphological evolution and 10...     

Effects of temperature on growth of the rice plant (Oryza sativa L.) in a controlled environment

I studied how temperature affects early growth, tillering, and spikelet number of the rice plant in artificially-lighted growth rooms. At early growth stages, growth rate increased as temperature rose from 22 to 31°C. During early stages, when growth largely depended on the seed reserve, the temperature quotient for growth rate was about 2. The effects of temperature on growth rate decreased with time. Tillering was more vigorous at high temperatures than at low temperatures. Spikelet number per panicle increased with decreasing temperatures.     

Uptake and metabolism of isouron in rice (Oryza sativa L.) seedlings

Summary Isouron, a pre-emergence herbicide, inhibited the growth of rice seedlings in a nutrient solution; the critical concentration was about 0.10 mg l^-1. Isotope studies showed that isouron, added to the nutrient solution, was observed by the rice roots and translocated rapidly to the shoot. In rice seedlings, isouron was converted to six known metabolites, 3-(5-(1-dimethyl-2-hydroxy-ethy)-3-isoxazolyl]urea, 3-(5-tert-butyl-3-isoxazolyl)-1-methylurea, 3-(5-tert-butyl-3-isoxazolyl)ure, 3-amino-5-tert-butylisoxazole, 3-[5-(1,1-dimethyl-2-hydroxyethyl)-3-isoxazolyl]-1-dimethylurea, and 3-[5-(1,1-dimethyl-2-hydroxyethyl)-3-isoxazolyl]-1-methylurea, and two unknown metabolites.     

Effects of inorganic fertilizers and micronutrients on methane production from wetland rice (Oryza sativa L.)

We compared the effects of adding different forms of nitrogenous fertilizers on the production of CH₄ in soil and on CH₄ emission from rice plants, Urea and diammonium phosphate gave the highest rates of CH₄ production from the soil and emission through rice plants, followed by (NH₄)₂SO₄. NaNO₃ was the least effective. The effects of micronutrients like Mo, Ni, or B were more prominent than those of Fe, Mn, Zn, V, or Co. It is concluded that CH₄ emission from rice paddies is influenced by both macro- and micronutrients, through effects on both microbial methanogenesis in soil and elimination through rice plants as a consequence of the effects on plant growth.     

水稻产量形成的生理生态研究进展

水稻产量形态规律是水稻育种和栽培的基础理论，已成为作物学研究的热点课题。从产量构成、光合生产和源库结构方面简介了水稻产量形成规律的生理生态研究进展，分析了3个方面的研究特点和构成产量形成过程的网络关系。同时水稻产量形成是一个动态过程，水稻产量性状的最终表现决定于其生长发育过程中众多基因的表达、调控和相互作用，提出应用现代发育遗传学与分子生态学的理论和方法，深入研究水稻产量的形成规律。     

Genetic diversity in Japanese aromatic rice (Oryza sativa L.) as revealed by nuclear and organelle DNA markers

Aromatic rice (Oryza sativa L.) cultivated in Japan is regionally differentiated by geographical distribution and characteristics. We aimed to characterize the lineage of Japanese aromatic rice using DNA markers. Based on analyses with nuclear SSR markers, we found that Japanese aromatic rice cultivars belong, with one exception, to japonica but showed some differences from authentic japonica and were divided into two clades that were distributed in western and eastern Japan, respectively. Further analyses with organelle markers showed that most of the cultivars in eastern Japan had cytoplasm characterized by tropical japonica, whereas most of those in western Japan had cytoplasm characterized by temperate japonica. We postulate that the ancestor of the cultivars in eastern Japan differs from those of the cultivars in western Japan, and that the two groups may have been separately introduced from Taiwan into Japan. The cytoplasm of aromatic rice cultivars in western Japan may have originated from tropical japonica and been substituted into the cytoplasm of temperate japonica through hybridization between tropical japonica as a male parent and temperate japonica as a female parent.     

The effect of in vitro digestion on steryl ferulates from rice (Oryza sativa L.) and other grains

Polished and cargo rice, wild rice, rice bran, corn bran, and wheat bran were subjected to a static in vitro digestion model, to monitor changes in their steryl ferulate content and composition. Free sterols, possible hydrolysis products of steryl ferulates, were also measured. Additionally, steryl ferulate bioaccessibility was calculated as the percentage of steryl ferulates liberated from the grain matrix into the digestive juice. Steryl ferulate content ranged between 6.1 and 3900 μg/g and decreased by 1-63% due to digestion. A parallel increase in free sterols of more than 70% was observed in all samples. Additionally, bioaccessibility of steryl ferulates was found to be almost negligible. These findings suggest that intestinal enzymes immediately hydrolyze steryl ferulates, which are liberated from the grain matrix, and thus they are practically unavailable for absorption in the small intestine. This further indicates that the hydrolysis products of steryl ferulates could be bioactive in the gut.     

Changing sink and source relations in rice (Oryza sativa L.) using carbon dioxide enrichment in the field

Rice plants in the field were enclosed in chambers covered with mylar film and subjected to CO² enrichment for 30 days before or after flowering. The CO² enrichment was intended to increase grain number (sink size) befiore flowering, and to increase photosynthesis of a canopy (source) after flowering.

The CO² enrichment before flowering increased grain number per unit land area and grain weight. The enrichment after flowering did not affect grain number but increased filled-grain percentage and grain weight. As a result, both treatments increased grain yield. Analysis of yield components indicates that a major factor responsible for the yield differences is grain number. It was also shown that the increase in yield was directly proportional to the dry matter increase after panicle initiation.

The CO² enrichment before flowering increased grain number per unit land area and grain weight. The enrichment after flowering did not affect grain number but increased filled-grain percentage and grain weight. As a result, both treatments increased grain yield. Analysis of yield components indicates that a major factor responsible for the yield differences is grain number. It was also shown that the increase in yield was directly proportional to the dry matter increase after panicle initiation.     

Asymmetric warming effects on N dynamics and productivity in rice (Oryza sativa L.)

Climate warming exhibits strong diurnal variations, with higher warming rates being observed at nighttime, which significantly affects rice (Oryza sativa L.) growth and grain yield. The objective of this study was to determine the effects of asymmetric warming (all-day warming, AW; daytime warming from 07:00 to 19:00, DW; nighttime warming from 19:00 to 07:00, NW, and a control, CK) on rice nitrogen (N) dynamics and productivity. Two rice bucket warming experiments were performed in Nanjing in Jiangsu Province, China, using the free air temperature increase (FATI) technique. The daily mean temperatures in the rice canopy in the AW, DW and NW plots were 2.0, 1.1 and 1.3ºC higher than those in the rice canopy in the CK plots, respectively. The results indicated that the total N accumulation of rice was 8.27–40.53% higher in the warming treatment than in the control during the jointing, anthesis and maturity stages. However, there was no significant difference detected among the three warming treatments. The warming treatment substantially decreased N translocation efficiency, leading to the retention of more N in the plant stems during grain filling. The warming treatment also decreased the N harvest index, N utilization efficiency based on grain yield and N utilization efficiencies based on biomass in both growing seasons. The warming treatment significantly increased the aboveground biomass (9.26–16.18%) in the jointing stage but decreased it (2.75–9.63%) in the maturity stage. Although DW increased the carbon (C) gain by photosynthesis and NW increased the C loss by night respiration, the daytime higher-temperature treatment affected rice photosynthesis and reduced its photosynthetic rate and product. This effect may be one of the primary reasons for the insignificant difference in the aboveground biomass between the DW and NW treatments. In the AW, DW and NW plots, the grain yield was reduced by an average of 10.07, 5.05 and 7.89%, respectively, across both years. The effective panicles and grains per spike tended to decrease in the warmed plots, whereas irregular changes in the 1000-grain weight were observed. Our results suggest that under the anticipated climate warming, rice productivity would further decline in the Yangtze River Basin.     

氮肥运筹对晚稻产量和氮素利用率的影响

用杂交水稻中优679为试验材料,研究氮肥运筹对晚稻产量和氮素利用率的影响。结果表明,在目标产量7 500 kg/hm2,总施氮量150 kg/hm2条件下氮肥运筹不同处理中,以基蘖肥∶穗肥=6∶4且基肥采用碳铵深施方式,其实际产量、齐穗后干物质生产量、成熟期干物质积累量、氮素利用率等均为最高。     

水稻雄蕊导管发育研究

本文以水稻粤泰保持系为材料，采用ATPase定位方法研究了单核至三核花粉期雄蕊导管的发育。单核边位花粉期，分化的导管胞质变浓厚、细胞核染色质浓缩、核转变为新月形并出现凋亡小体；此外，导管内物质也可以大分子形式直接撤离。单核边位晚期，雄蕊导管发育成熟。在二核和三核花粉期，导管内重新出现具有ATPase活性的物质，同样的现象也存在于农垦58s可育花药成熟导管中。以上结果暗示水稻雄蕊导管分化存在程序性死亡及非程序性死亡多种途径，水稻成熟导管内具有ATPase活性物质可能是一种普遍现象。     

Effects of organic amendments on rice (Oryza sativa L.) growth and uptake of heavy metals in contaminated soil

Journal of Soils and Sediments - Previous studies showed that rapeseed cake increased rice grain yields and significantly lowered the heavy metal concentrations in the brown rice. The pH, dissolved...     

不同类型水稻籽粒灌浆的生理生化特性研究

以3个较大穗型的不同类型水稻品种(组合)“IR_(65600-85)”、“培矮64S/E32”、“Ⅱ优86”为材料,试验研究水稻籽粒灌浆特性及其有关生理生化活性变化结果表明,3个水稻的强势粒起始生长势均高于弱势粒,从而更早进入灌浆盛期;ADPG焦磷酸化酶活性强势粒高峰值均出现在花后6d,弱势粒峰值出现在花后12d;淀粉合成酶活性强势粒在花后0～18d高于弱势粒,尔后弱势粒高于强势拉,但“IR_(65600-85)”弱势粒后期活性仅弱高于强势粒,造成3个水稻的弱势粒灌浆不如强势粒,尤其是“IR_(65600-85)”弱势粒生理生化活性更低,其籽粒充实最差,结实率也最低。     

Areal variation in the relationship between natural 15N abundances of rice (Oryza sativa L.) and soil

This study was performed to clarify whether areal variation exists in the relationship between natural ¹⁵N abundances (δ¹⁵N values) of rice (Oryza sativa L.) and soil without an applied nitrogen (N) source, and to explore possible reasons for any areal variation. We investigated the relationships between δ¹⁵N values of rice and those of unamended soil with no applied N source in two locations; Daisen and Ogata, in Akita Prefecture, Japan. The δ¹⁵N values of rice in Daisen were higher than those in Ogata from 2007 to 2009, irrespective of the cropping year. Results demonstrated areal variation in the relationship between δ¹⁵N values of rice and those of unamended soil. The variation might be attributed to variation in the δ¹⁵N of natural N input and to ammonia nitrification and subsequent denitrification. When the relationship between δ¹⁵N values of rice and those of unamended soil is used to discriminate between organic and conventional rice, the areal variation of the relationship in the target area should be taken into account, from the point of the δ¹⁵N value of natural N input and N transformation in the soil.     

大田条件下模拟UV-B辐射滤减对水稻生长及内源激素含量的影响

对大田栽培条件下人工模拟的UV-B辐射滤减环境对晚稻品种“协优432”的叶绿素含量、株高、内源激素吲哚乙酸(IAA)、脱落酸(ABA)、赤霉素(GA3)、玉米素(Zeatin)含量的影响研究结果表明,在正常日光处理组与UV-A滤光组之间叶绿素a含量变化显著;正常日光处理组与UV-A滤光组、UV-A UV-B滤光组之间株高无明显变化。UV-A UV-B滤光组IAA、GA3、Zeatin含量分别比正常日光处理组降低了40.42%、48.60%、36.21%;分别比UV-A滤光处理组降低了36.52%、70.94%、54.54%。单因素方差分析及多重比较结果显示,UV-A UV-B滤光组与正常日光处理组之间IAA、GA3含量差异显著;UV-A UV-B滤光组与UV-A滤光处理组之间GA3、Zeatin含量差异显著。UV-A UV-B滤光组ABA含量比正常日光处理组降低了29.74%,比UV-A滤光处理组降低了5.19%,经单因素方差分析后发现差异不显著。     

Establishment of Azorhizobium caulinodans in the rhizosphere of wetland rice (Oryza sativa L.)

 Azorhizobium caulinodans strongly colonized the rhizosphere of rice plants after incorporation of Sesbania rostrata in a field trial throughout the growing season and during the fallow period until 19 weeks after incorporation of S. rostrata. A. caulinodans became well established in the rhizosphere (7.17 log cfu g^–1 dry rice root) and colonized subsequent S. rostrata test plants. Three traditional and three improved high-yielding rice varieties were inoculated with A. caulinodans under gnotobiotic conditions. In none of the combinations did acetylene reduction activity significantly increase. Ethylene production on colonized rice roots only started after the growth medium had been supplemented with an extra C source (0.1 to 0.25% Na-lactate). This indicates that the bacterial nitrogenase activity is limited by energy supply. Four possible inoculant-carriers (peat, coir dust, bagasse, rice straw) were compared for long-term survival of the bacterial strain. Independent of the storage temperature (26  °C or 4  °C), the survival of A. caulinodans in peat and coir dust was very high during a 12-month period (>8 log cfu g^–1 dry carrier), whereas the bagasse and rice straw carriers showed a serious decline from 3 months onwards. Received: 6 April 1999     

Crop growth and nitrogen transformations in wheat (Triticum aestivum L.) planted after wetland rice (Oryza sativa L.)

Summary A field study was undertaken to examine the effects of various management strategies on wheat (Triticum aestivum L.) performance and N cycling in an intensively cropped soil. Microplots receiving 100 kg N ha^–1 as¹⁵NH₄ ^{+ 15}NO₃ ^– at sowing, tillering or stem elongation were compared with unfertilized microplots. Stubble from the previous rice crop was either incorporated, burnt without tillage, burnt then tilled or retained on the surface of untilled soil. Wheat grain yield ranged from 1.5 to 5.1 t ha^– and was closely related to N uptake. Plant accumulation of soil N averaged 36 kg N ha^–1 (LSD 5% = 10) on stubble-incorporation plots and 54 kg N ha^–1 on stubble-retention plots. Fertilizer N accumulation averaged 18 kg N ha^–1 (LSD 51% = 6) on stubble-incorporation plots and 50 kg N ha^–1 on stubble-retention plots. Tillage had little effect on burnt plots. Delaying N application from sowing until stem elongation increased average fertilizer N uptake from 26 to 39 kg N ha^–1 (LSD 5% = 6), but reduced soil N uptake from 50 to 37 kg N ha^– (LSD 5% = 10).Immobilization and leaching did not vary greatly between treatments and approximately one-third of the fertilizer was immobilized. Less than 1% of the fertilizer was found below a depth of 300 mm. Incorporating 9 t ha^–1 of rice stubble 13 days before wheat sowing reduced net apparent mineralization of native soil N from 37 to 3 kg ha^–1 between tillering and maturity. It also increased apparent denitrification of fertilizer N from an average 34 to 53 kg N ha^–1 (LSD 5% = 6). N loss occurred over several months, suggesting that denitrification was maintained by continued release of metabolizable carbohydrate from the decaying rice stubble. The results demonstrate that no-till systems increase crop yield and use of both fertilizer and soil N in intensive rice-based rotations.