Relationship between grain filling duration and leaf senescence of temperate rice under high temperature

High temperature during grain filling period has been reported to decrease the grain filling duration, leading to the lower grain weight and yield of rice. Two experiments in the phytotron and field were carried out to test the hypothesis that the leaf senescence of rice plants may determine the grain filling duration under high temperature. In the phytotron experiment in 2008, rice plants of a japonica cultivar “Ilpumbyeo” were subjected to three minimum/maximum (mean) temperature regimes of 11/19 (15), 17/25 (21), and 23/31 °C (27 °C). In the field experiment, rice seedlings of the same rice cultivar were transplanted on May 6th and June 19th in 2009 and the mean temperatures during the grain filling period were 24.4 and 21.9 °C, respectively. Both experiments revealed consistently that high temperature increased the rates of grain filling and leaf senescence while it reduced the durations of them. However, grain filling was terminated earlier than complete leaf senescence, the time gap being greater at higher temperature. In addition, the fraction of dry matter partitioning to the leaf sheath + culm resumed to increase following the termination of grain filling under high temperature, indicating that leaves were still maintaining photosynthetic capacity and supplying assimilates into the other plant tissues except grain even after the termination of grain filling. These findings suggest that an early termination of grain filling in temperate rice under high temperature was not resulted from the lack of assimilate owing to the early leaf senescence but from the loss of sink activity owing to the earlier senescence of panicle.     

Modeling the effects of light, carbon dioxide, and temperature on the growth of potato

This study examined the effects of light, temperature and carbon dioxide on the growth of potato (Solanum tuberosum L.) in a controlled environment in order to ascertain the best growing conditions for potato in life support systems in space. 'Norland' and 'Russet Burbank' were grown in 6-L pots of peat-vermiculite for 56 d in growth chambers at the University of Wisconsin Biotron. Environmental factor levels included continuous light (24-h photoperiod) at 250, 400, and 550 micromoles m-2 s-1 PPF; constant temperature at 16, 20, and 24 degrees C; and CO2 at approximately 400, 1000, and 1600 microliters L-1. Separate effects analysis and ridge analysis provided a means to examine the effects of individual environmental factors and to determine combinations of factors that are expected to give the best increases in yields over the central design point. The response surface of Norland indicated that tuber yields were highest with moderately low temperature (18.7 degrees C), low CO2 (400 microliters L-1) and high light (550 micromoles m-2 s-1 PPF). These conditions also favored shorter stem growth. Russet Burbank tuber yields were highest at moderately low temperature (17.5 degrees C), high CO2 (1600 microliters L-1) and medium analyses will be used to project the most efficient conditions for growth of potatoes in closed ecological life support systems (CELSS) in space colonies.     

日照时间、积温和降水量对籽棉产量的影响

为寻求影响籽棉产量的关键气象因子,建立二者之间的回归模型,采用灰色关联分析法分析了2010―2020年同一施肥条件下棉花籽棉产量与4―10月主要气候因子的关系。结果表明,影响籽棉产量的最重要气候因子是4―10月日照时间,关联度为0.430 7;其次是≥15 ℃积温,关联度为0.386 4;再次是≥20 ℃积温,关联度为0.348 3。逐步回归分析结果表明,4―10月≥10 ℃积温、日照时间、降水量是影响籽棉产量的正效应气候因子。6―8月产量形成关键期的15个气候因子中,6月降水量、7月≥10 ℃积温、8月日照时间对籽棉产量的影响均为正效应,而8月≥20 ℃积温为负效应因子。     

Bird,weed and interaction effects on yield of irrigated lowland rice

Weeds and grain feeding birds are the two main biological causes of yield losses in irrigated rice in Africa. To quantify the single and combined effect of these biological constraints on rice yields, and to investigate whether weeds attract birds and thereby contribute to increased bird damage, a three-year factorial experiment was set-up in the Senegal River Valley. We tested two management factors (bird and weed management), each with two levels (‘complete’ and ‘absent’), and one crop cycle factor also with two levels (Sahel 202, a medium-cycle and Sahel 108, a short-cycle rice cultivar). Season-long competition from weeds resulted in high but predictable yield losses ranging from 50% to 75%, with lower yield losses for the medium-cycle cultivar Sahel 202 in two of the three seasons. Due to the nature of the pest, season-long exposure to birds resulted in less predictable yield losses ranging from 13% to as high as 94%, with high seasonal variation. In two seasons, much lower bird-inflicted yield losses were observed in the short-cycle cultivar Sahel 108, whereas in one season the medium-cycle cultivar Sahel 202 was much less damaged. When rice was exposed to both weeds and birds, the relative yield losses ranged from 80 to 99%. The yield reducing effect of weeds and birds was never additive. Bird visits to a weedy crop were more frequent compared to a weed-free crop at least in the early rice grain filling stages. This attraction of birds by weeds resulted in an additional yield loss in five of the six cases, ranging from 2 to 62%. Bird-inflicted yield losses in irrigated rice may be reduced by keeping the crop, as much as possible, free from weeds.     

Study of water stress effects in different growth stages on yield and yield components of different rice (Oryza sativa L.) cultivars

A field experiment was conducted during 2001-2003 to evaluate the effect of water stress on the yield and yield components of four rice cultivars commonly grown in Mazandaran province, Iran. In northern Iran irrigated lowland rice usually experiences water deficit during the growing season include of land preparation time, planting, tillering stage, flowering and grain filing period. Recently drought affected 20 of 28 provinces in Iran; with the southeastern, central and eastern parts of the country being most severely affected. The local and improved cultivars used were Tarom, Khazar, Fajr and Nemat. The different water stress conditions were water stress during vegetative, flowering and grain filling stages and well watered was the control. Water stress at vegetative stage significantly reduced plant height of all cultivars. Water stress at flowering stage had a greater grain yield reduction than water stress at other times. The reduction of grain yield largely resulted from the reduction in fertile panicle and filled grain percentage. Water deficit during vegetative, flowering and grain filling stages reduced mean grain yield by 21, 50 and 21% on average in comparison to control respectively. The yield advantage of two semidwarf varieties, Fajr and Nemat, were not maintained under drought stress. Total biomass, harvest index, plant height, filled grain, unfilled grain and 1000 grain weight were reduced under water stress in all cultivars. Water stress at vegetative stage effectively reduced total biomass due to decrease of photosynthesis rate and dry matter accumulation.     

Photoperiod shift effects on yield characteristics of rice

Edible yield must be maximized for each crop species selected for inclusion in the Controlled Ecological Life-Support System (CELSS) proposed by NASA to support long-term manned space missions. In a greenhouse study aimed at increasing biomass partitioning to rice (Oryza sativa L.) grain, plants of the high yielding semi-dwarf rice cultivar Ai-Nan-Tsao were started in pots under 8-h photoperiods at a density of 212 plants m-2. After different periods of time under 8-h photoperiods, pots were switched to continuous light for the remainder of the cropping cycle. Continuous light did not delay time to first panicle emergence (60 d) or time to harvest (83 d). There was a positive correlation between the length of continuous light treatments and nongrain biomass. Grain yield (1.6 +/- 0.2 g plant-1) did not increase in continuous light. Yield-efficiency rate (grain weight per length of cropping cycle, canopy volume, and weight of nongrain shoot biomass) was used to compare treatments. Small Ai-Nan-Tsao rice canopies grown under 8-h photoperiods were more efficient producers of grain than canopies grown under continuous light for a portion of the rice cropping cycle.     

Kenaf seed storage duration on germination,emergence, and yield

Kenaf (Hibiscus cannabinus L.) is a potential alternative crop being developed for fiber production. Because planting area varies dramatically from year to year, seed supplies may greatly exceed use so that the excess seed must be stored for one to several years. The objectives of this study were to determine the effect of seed storage duration at 10 °C on germination, vigor, emergence, and yield. Replicated trials were established at Starkville, MS in 1999 and 2000 to evaluate field emergence and biomass yield of kenaf seed from five ‘Everglades 41’ (‘E41’) harvest year seed lots stored at 10 °C in ambient relative humidity for up to 4 years. Germination of these same seed lots under standard (20–30 °C) and cool (20 °C) temperatures, and seed vigor was evaluated over time. Field emergence was the same for the different seed storage durations up to 4 years, but was directly affected by drought conditions for each planted year. Biomass yields ranged from 12.39 to 14.57 Mg ha⁻¹ in 1999 and 16.82 to 18.47 Mg ha⁻¹ in 2000, but were not different between storage durations. Seed germination remained greater than 80% regardless of storage duration. Electrolyte leakage, based on conductivity, was 38–50% less with freshly harvested seed than seed stored for 4 years at 10 °C. However, neither the conductivity nor accelerated aging test were reliable predictors of field emergence. Kenaf seed stored up to 4 years at 10 °C retained germination rates acceptable for commercial use. Neither field emergence nor biomass yield was affected by seed storage duration.     

Carbon dioxide enrichment and temperature effects on cotton canopy photosynthesis,transpiration, and water-use efficiency

The objectives of this study were to evaluate effects of ambient and double ambient [CO₂] at a range of growing temperatures on photosynthesis, respiration, transpiration, water-use efficiency and dry matter accumulation of cotton plants (Gossypium hirsutum L., cv. DPL 50). In Experiment I, plants were grown outdoors until first bloom, then transferred into naturally lit growth chambers and grown for 22 days at 30/18°C with five CO₂ concentrations varying from 350 to 900 μl l⁻¹. In Experiment II, air temperatures were maintained at 20/12, 25/17, 30/22, and 35/27°C day/night during a 70-day experimental period with [CO₂] of 350 and 700 μl l⁻¹ at each temperature. Photosynthesis increased with [CO₂] from 350 to 700 μl l⁻¹ and with temperature. Plants grown at 35/27°C produced fewer bolls due to abscission compared with plants grown at optimum temperatures (30/20°C). At higher [CO₂], water-use efficiency increased at all temperatures due mainly to increased canopy photosynthesis but also to more limited extent to reduced canopy transpiration. Increased photosynthesis at higher [CO₂] resulted in greater dry matter accumulation at all temperatures except at 20/12°C. Respiration increased as dry matter and temperature increased. Plants grown at higher [CO₂] had less respiration per unit dry matter but more per unit area. These results indicate that future increases in [CO₂] are likely to benefit cotton production by increasing carbon assimilation under temperatures favorable for cotton growth. Reduced fruit weights at higher temperatures indicate potential negative effects on production if air temperatures increase as projected in a high-CO₂ world.     

Drought stress and tropical maize: QTLs for leaf greenness, plant senescence, and root capacitance

Genetically improved crops with higher water productivity help maintaining and increasing agricultural production in drought-prone areas. Their development involves, as in the case of maize, selection for high grain yield and improved secondary traits. With the objective of better understanding the role and regulation of the morphology of drought adaptation, a recombinant inbred line (RIL) population of tropical maize (Zea mays L.) was evaluated in six field experiments under intermediate (IS) and severe (SS) drought stress at flowering and under well-watered (WW) conditions in Mexico. The analyses per water regime revealed 32 quantitative trait loci (QTLs) for the five measurements of relative content of leaf chlorophyll (CL), 25 for the five visual ratings of plant senescence (SEN), and 11 for the three measurements of electric root capacitance (RCT). Impressive clusters of QTLs were observed on chromosomes 2 (bins 2.03-05), 4 (bin 4.09), and 10 (bins 10.04-05), suggesting that a small number of genes control chlorophyll metabolism and plant senescence. The high CL and low SEN of the drought resistant parent are aspects of its high water productivity resulting from improved constitutive traits. Co-locations of QTLs for CL, SEN and RCT with QTLs for plant height (PHT), the anthesis-silking interval (ASI), and grain yield (GY) were observed in bins 1.06-07, 8.06, and 4.09 but not for the large QTL clusters on chromosomes 2 and 10, suggesting independent genetic control of reproductive traits. Still, the phenotypic data showed that high CL and low SEN were favorable for grain yield production under drought, while delayed SEN was associated with higher grain yield under WW conditions. CL and SEN are suitable to complement selection for drought tolerance in order to sustain future breeding progress.     

覆膜栽培对中稻-再生稻生育期及产量的影响

水稻收割后稻桩上存活的休眠芽 ,在适宜的水、温、光和养分条件下 ,萌发再生蘖 ,进而抽穗成熟的一季水稻称为再生稻。水稻再生利用是一种省工、省种、省肥、省水、省药、种一季收两熟的高效水稻栽培技术 ,１９９６年以来 ,在浙西南山区推广应用面积逐年增加 ,至今已累计推广近７０００ｈｍ２,共增产稻谷２．８３多万ｔ,增值３２００多万元 ,增加纯收入２１００多万元 ,取得了较好的社会效益和经济效益。但如何提高山区烂糊田的中稻 -再生稻产量这一问题 ,一直是许多基层农技人员工作的难点。为了探索烂糊田中稻 -再生稻高产途径 ,我们借鉴地…     

含糖蜜液生物液体富硒叶面肥对稻米锌硒含量及其产量的影响

为证实含糖蜜液生物液体富硒叶面肥的增硒、锌与增产效果,2015~2016年使用含糖蜜液生物液体富硒叶面肥等几种含硒叶面肥对水稻进行田间叶面喷施试验。结果显示:水稻喷施含糖蜜液生物液体富硒叶面肥的稻米硒含量比其他叶面肥处理及对照区高0.21~0.598mg/kg,锌含量高6.30~14.6mg/kg,产量高5.22%~13.85%。表明含糖蜜液生物液体富硒叶面肥增加锌硒含量与增产效果明显,具有一定的推广应用价值。     

Effects of soil water deficit at different growth stages on rice growth and yield under upland conditions. 2. Phenology,biomass production and yield

Phenological development, shoot dry matter production, grain yield and yield components of rice were examined in relation to drought occurring at various stages of growth. Rice was sown three or four times at three-week intervals in the field in each of two years, and performance in three stress trials was compared with that in corresponding irrigation trials, with the aim of quantifying the response of the crop to water stress of 23–34 days' duration developing at different growth stages. When drought occurred during vegetative stages, it had only a small effect on subsequent development and grain yield. The reduction in yield of up to 30% was due to reduced panicle number per unit area in one trial, and reduced number of spikelets per panicle in another. The effect of water stress on yield was most severe when drought occurred during panicle development. Anthesis was delayed, the number of spikelets per panicle was reduced to 60% of the irrigated control and the percentage of filled grains decreased in one crop to zero. This decrease in grain yield to less than 20% of the control was associated with low dry matter production during the drought period as well as during the recovery period following the drought. When drought occurred during grain filling, the percentage of filled grains decreased to 40% and individual grain mass decreased by 20%. The effect of stress was also related to its severity during grain filling. Stress at this stage hastened maturity. The results suggest that variation in yield components due to water availability is related to the variation in dry matter production at particular growth stages. Results of a supplementary shading experiment show that the relationship between spikelet number per panicle or single grain mass and crop growth rate was the same, whether growth rate was varied by availability of soil water or solar radiation. Filled-grain percentage, however, was more sensitive to drought stress than shading when comparison was made at a similar crop growth rate.     

Modeling light and temperature effects on leaf emergence in wheat and barley

Phenological development affects canopy structure, radiation interception, and dry matter production; most crop simulation models therefore incorporate leaf emergence rate as a basic parameter. A recent study examined leaf emergence rate as a function of temperature and daylength among wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) cultivars. Leaf emergence rate and phyllochron were modeled as functions of temperature alone, daylength alone, and the interaction between temperature and daylength. The resulting equations contained an unwieldy number of constants. Here we simplify by reducing the constants by > 70%, and show leaf emergence rate as a single response surface with temperature and daylength. In addition, we incorporate the effect of photosynthetic photon flux into the model. Generic fits for wheat and barley show cultivar differences less than +/- 5% for wheat and less than +/- 10% for barley. Barley is more sensitive to daylength changes than wheat for common environmental values of daylength, which may be related to the difference in sensitivity to daylength between spring and winter cultivars. Differences in leaf emergence rate between cultivars can be incorporated into the model by means of a single, nondimensional factor for each cultivar.     

Effect of planting date,fungicide timing and cultivar susceptibility on severity of narrow brown leaf spot and yield of rice

Narrow brown leaf spot (NBLS) of rice (Oryza sativa L.) is caused by Cercospora janseana (Racib). O. Const. (Synonyms: Cercospora oryzae Miyake, Passalora janseana Racib. U.). Experimental studies were conducted at Rice Research Station, Louisiana State University, and Agricultural Center, Crowley, to manage NBLS by fungicide application of propiconazole at different growth stages of rice cultivars having different susceptibility levels to NBLS in different planting dates. Results of these studies revealed that April (early) had less NBLS severity as compared to May (late) planting. Very susceptible cultivars, CL131 and Cheniere, had the highest and resistant cultivars, Della and Presidio, had the lowest NBLS severity at both the planting dates. Propiconazole application significantly reduced the NBLS severity in comparison to untreated. Fungicide application at panicle initiation was the most effective time to manage NBLS on the very susceptible and susceptible cultivars at both planting dates. NBLS on moderately susceptible cultivars was best managed by applying fungicide either at panicle initiation or early boot stage in early planting but panicle initiation was the best time to apply fungicide in late planting. Resistant cultivars did not need fungicide in April planting but did need in May planting. Rice yield was determined to be higher in April than May planting. Fungicide application at early boot stage protected the yield by 9.4% in April planting and 34.2% when applied at panicle initiation in May. Susceptible cultivar, Cheniere, exhibited the greatest yield and resistant cultivars had lowest yield in both the planting dates regardless of its susceptibility level to NBLS. Yield of very susceptible to susceptible cultivars was reduced in late planting but no effect was observed on yield of moderately susceptible and resistant cultivars.     

Nitrogen nutrition and temporal effects of enhanced carbon dioxide on soybean growth

Plants grown on porous media at elevated CO2 levels generally have low concentrations of tissue N and often appear to require increased levels of external N to maximize growth response. This study determines if soybean [Glycine max (L.) Merr. Ransom'] grown hydroponically at elevated CO2 requires increases in external NO3- concentrations beyond levels that are optimal at ambient CO2 to maintain tissue N concentrations and maximize the growth response. This study also investigates temporal influences of elevated CO2 on growth responses by soybean. Plants were grown vegetatively for 34 d in hydroponic culture at atmospheric CO2 concentrations of 400, 650, and 900 microliters L-1 and during the final 18 d at NO3- concentrations of 0.5, 1.0, 5.0 and 10.0 mM in the culture solution. At 650 and 900 microliters L-1 CO2, plants had maximum increases of 31 and 45% in dry weight during the experimental period. Plant growth at 900 microliters L-1 CO2 was stimulated earlier than at 650 microliters L-1. During the final 18 d of the experiment, the relative growth rates (RGR) of plants grown at elevated CO2 declined. Elevated CO2 caused increases in total N and total NO3(-)-N content and leaf area but not leaf number. Enhancing CO2 levels also caused a decrease in root:shoot ratios. Stomatal resistance increased by 2.1- and 2.8-fold for plants at the 650 and 900 microliters L-1 CO2, respectively. Nitrate level in the culture solutions had no effect on growth or on C:N ratios of tissues, nor did increases in CO2 levels cause a decrease in N concentration of plant tissues. Hence, increases in NO3- concentration of the hydroponic solution were not necessary to maintain the N status of the plants or to maximize the growth response to elevated CO2.     

Grain filling duration,a crucial determinant of genotypic variation of grain yield in field-grown tropical irrigated rice

Grain filling, a crucial determinant of grain yield in cereal crops, is characterized by duration and rate of grain filling. This study aimed to (1) seek genotypic variations in grain filling duration and rate on area basis, (2) compare the contribution of grain filling duration and rate to grain yield and (3) examine the influence of temperature and solar radiation on grain filling duration and rate for effective grain filling period in the field-grown tropical irrigated rice. Six tropical genotypes were used in the 2004 dry season and wet season at the International Rice Research Institute (IRRI), Laguna, Philippines.     

Associative effects of leaf roll and ring rot on disease expression and yield of potatoes

Netted Gem potato plants infected with either the ring rot bacterium (Corynebacterium sepedonicum) or the potato leaf roll virus alone exhibited typical symptoms of the respective diseases. Plants infected with both the bacterium and the virus exhibited severe leaf roll. Typical ring rot symptoms were masked in dual infections, thereby increasing the difficulty in detection of the bacterial disease. The combined yield-reducing effect of the two pathogens was greater than that of the potato leaf roll virus and was similar to that caused by ring rot alone.     

立丰灵对水稻抗倒性和产量的调控效果

水稻倒伏是高产和机械收割的重大威胁.抗倒性化学调控日益引起关注.20世纪80年代日本研发的多效唑(MET)具有矮化稻株,增强抗倒性的功能.近年中国农业大学开发出一种新型矮化剂立丰灵,主要成分为调环酸钙盐.3a 试验结果表明,立丰灵对水稻具有增强抗倒性和促进生殖生长的双重效能.2005年进行6.7hm2示范,骥以进一步验证立丰灵对水稻抗倒性和产量的调控效果.     

Quantitative effects of cultural practices on growth and yield of forage rice having short panicles

Cultivation of forage rice for whole-crop silage has been increasing in Japan and will be important in Asia. In this study, effects of cultural practices on growth and yield of a forage rice cultivar “Tsukisuzuka” having short panicle 1 allele were analysed quantitatively using linear mixed model. The contribution of basal dressing to dry yield per 1 g/m² nitrogen fertilizer was larger than that of topdressing. In addition, topdressing 30 and 20 days before heading was considered to have the disadvantage of increasing risk of lodging and panicle weight respectively. Effects of weather elements on growth of forage rice were also speculated. In tested fields, high solar radiation at seedling and tillering stage was considered important for the high yield. As the number of continuous cropping cycles increased, growth of forage rice got worse. And application of compost improved growth of forage rice. Elemental analysis of soil and plants revealed that this continuous cropping obstacle was likely to attributed to deficiency of potassium. In addition, potassium deficiency increased panicle weight of a forage rice cultivar having short panicle 1 allele. Therefore, control of potassium nutrition will be useful for both sustaining productivity (sufficient application of potassium) and seed production (restriction of potassium). These findings will be useful for improvement of cultivation method of forage rice.     

30％普菌克WP防治水稻细菌性条斑病药效试验

水稻细菌性条斑病是国内植物检疫对象。近年来在晚稻上流行频率较高 ,为害损失渐趋严重 ,成为晚稻的主要病害之一。为了有效控制水稻细菌性条斑病的流行 ,我们于２０００年８～９月对３０%普菌克ＷＰ进行了田间药效试验 ,现将试验结果报道如下 :一、材料与方法１.供试药剂３０%普菌克ＷＰ,系广东省罗定市生物化工有限公司生产 ;２０%龙克菌ＳＣ ,系浙江省温州市龙湾化工厂生产 ,５０%杀菌王ＷＰ ,系浙江省诸暨市农化厂生产 ;５%菌毒清ＡＣ ,系山东省绿野化学有限公司生产 ;２０%叶青双ＷＰ,系浙江省温州市东风农药厂生。２.试验设计本试验设…