Changes in Leaf Stomatal Properties in Rice with the Growing Season

Transplanting rice varieties grown in different seasons can lead to different yields due to different dry matterproduction. Early-season rice varieties transplanted in the late season can obtain high yields with short-growthduration and higher yields driven by higher dry matter production. To make clear the variations in dry matterproduction across seasons, four early-season rice varieties were chosen for late-season transplantation. The grainyield, dry matter accumulation, leaf photosynthetic, and leaf stomatal properties were studied. It was observedthat the average yields of these four varieties in the late season were 33% greater, despite a reduced growth periodof 13 days in comparison with the early season. Furthermore, there was a notable increase in both total and postheadingdry matter production during the late season. The leaf net photosynthetic rate, stomatal area, stomatalwidth, and stomatal length were higher in the late season. Despite no significant difference in stomatal densitybetween seasons, strong positive linear relationships were observed between net photosynthetic rate and stomatalconductance, and between stomatal conductance and area. These relationships demonstrate that the increase ofthe stomatal width and length of the leaves in the late season leads to an increase in the stomatal area, therebyincreasing the stomatal conductance and enhancing the photosynthesis of the leaves. Consequently, this leads togreater dry matter production and a higher yield compared to the early season. Therefore, when breeding newhigh-yielding and short-growing varieties, the large stomatal area can be used as a reference index.

Diversity of Flower Opening Time and Duration in Rice (Oryza sativa ssp. indica) Landraces of South and Southeast Asia in Different Cultivation Seasons

Different cultivars of rice(Oryza sativa)open at different times of the day,and the overlap of anthesis time in rice between the neighbouring cultivars is of crucial importance to the degree of cross pollination in rice.Nevertheless,none of the past experiments with cross pollination between different rice cultivars ever reported the respective flower opening time(FOT)and flower exposure duration(FED)of the parent cultivars,until recently.The authors present here the first record of FOT and FED of 1114 indica rice landraces of South and Southeast Asia,growing during sum-mer and winter seasons in three consecutive years.The authors also present an analysis of the influences of the grow-ing season on the anthesis behaviour,and present the first records of the FOT and FED variability on sunny and cloudy days of a large number of landraces.The data show that rice florets tend to open later in the morning(that is,take longer time to anthesis after sunrise)on sunny days than on cloudy days,and also significantly later during long day seasons(spring and summer)than during short day season(winter);and that FED is inversely related to both FOT and the length of duration from sunrise to first flower opening.The wide ranges of FOT(8:50 a.m.to 12:40 p.m.)and FED(15 to 194 minutes)also suggest the ample time window for receiving pollen from neighbouring cultivars with differ-ent FOT,enhancing the chances of cross pollination between hundreds of rice landraces with FOT and FED overlaps.

Key Techniques of an Ecological Pattern“Planting Rice in One Season and Breeding Red Swamp Crawfish in Three Seasons” for Green Production in Lixiahe Region of Jiangsu Province

Three big field projects, independent irrigation and drainage facilities, and a blocking net, which are auxiliary projects of a green planting and breeding pattern composed of rice and red swamp crawfish （Procambarus clarkii）, spatial and temporal coupling technology of ＂planting rice in one season and breeding red swamp crawfish in three seasons＂, green fertilization technology, green prevention and control technology, control technology of water level, and throwing technology of bait in Lixiahe region of Jiangsu Province were introduced successively, which can provide technical support for the development of ecological planting and breeding patterns and realization of green production in paddy fields.

Research on the Dynamic Climatic Production Potential of Middle-season Rice in Jiangxi Province

According to the meteorological data from Meteorological Station during 1961-2007 in Jiangxi Province,using the calculation method of production potential of climate recommended by Food and Agriculture Organization(FAO),the variation trends of climatic potential productivity of mid-season rice during this period were analyzed.The results indicated a trend of yearly decline in the variation of photosynthetic and light-temperature potential productivity in Jiangxi.The changes of climatic production potential fluctuated widely.The main reasons for the above-mentioned changes in recent years included more serious air pollution,resulting in less light and decline in photosynthetic potential productivity.An increase in extreme high-temperature days inhibited the growth of mid-season rice.The uneven distribution of precipitation resulted in the volatility of climatic production potential.To ensure high and stable yield,some counter-measures should be taken,including increasing weather modification input,building water conservancy facilities,enhancing the accuracy of weather forecasts and strengthening the research on climate changes.All the methods could solve those problems so as to ensure an improvement in rice production capacity to address climate change.

Genetic Analysis on Plant Height in Rice in Different Growing Seasons

[Objective] The aim was to carry out the genetic analysis on plant height of rice（Oryza sativa L.）cultivated in different seasons.[Method] Three rice parents with great difference in plant height including CB1（83.1 cm）,CB4（105.5 cm）and CB7（115.6 cm）were chosen to construct two parental combinations：CB1×CB4 and CB7×CB4,and the corresponding filial generations P1,F1,P2,B1,B2 and F2 were obtained.The 6 populations were planted in middle and late seasons respectively to measure their height traits.The Akaike＇s information criterion（AIC）of the mixed major gene and polygene model was used to indentify the existence of major genes affecting quantitative traits in B1,B2,F2 populations.When the major genes existed,the genetic effects of the major genes and polygenes and their genetic variance were estimated through segregation analysis.[Result] One additive major gene plus additive-dominance polygenes was the most fitted genetic model for the trait in all B1,B2,F2 populations in two planting seasons.The heritability values of the major genes varied from 38.63% to 78.53% and those of polygenes varied from 1.72% to 36.04%,and the total heritability values were 45.52-92.93%.The additive effect d value of the two genetic populations under two planting seasons was-4.56,-9.16,-7.19,and-9.38,respectively,as suggested that additive effect of the major genes would decrease the express of the plant height trait.[Conclusion] The heritability of plant height trait was affected by planting seasons and the combinations clearly as a whole.

Recent Climatic Effects on Seasonal Rice Yields in Bangladesh： A Statistical Overview

Expecting that agricultural yield is highly dependent on climatic conditions, particularly water availability and suitable temperature, an agroclimatic study was carried out on rice crops during three different seasons in four regions of Bangladesh. Data on climate （surface air temperature and precipitation） and seasonal rice production were examined for the period 1986-2006 from 18 rice growth observatories. The relationship between climate and rice production was statistically analyzed by removing long-term trends so that the effects of improved irrigation, which results in a general increase in crop production, may be removed. The analysis involved both single and multiple regressions. The results suggested that, during monsoon and summer, higher temperatures had negative effects on rice production, especially in the northwestern （NW） region. In winter, positive effects were observed throughout Bangladesh. Since the annual mean temperature was positively correlated with those in the three seasons individually, the annual temperature had negative effects on the annual rice production only in the NW region, while it had positive effects in the central and southern regions. With the exception of the NW region, it was basically dry, excessive rainfall both in summer and monsoon yielded floods and reduced rice yield. In winter, more rainfall showed positive effects on crop production only in the central region, which was least irrigated. These findings suggested that accelerated atmospheric warming would result in serious damage to crops during summer and monsoon. Reliable prediction of future crop production will rely on the temperature and rainfall trends in individual seasons.

Amylose Content and Starch Granule Size in Rice Grains are Affected By Growing Season

Amylose content and starch granule size in grains influence rice quality,which differs between the early(ES)and late season(LS).The objective of this study was to determine the variation of amylose content and starch granule size between seasons and find the main reasons(e.g.,temperature and solar radiation)for the observed variation.Field experiments with six rice varieties(three high and three low amylose content rice)planted in the ES and LS were conducted in 2016 and 2017,respectively.The mean temperatures during the filling stage were higher in ES,however,the daily temperatures at 7-10 days after flowering(DAF)in 2016,and at 5-10,13-14 DAF in 2017 were higher in LS.The results showed that amylose content in LS was lower than in ES with high amylose content rice varieties(HACV);the opposite trend occurred with low amylose content rice varieties(LACV).The mean starch granule diameter was higher in LS than ES in 2016,but the opposite result occurred in 2017 with all rice.Our results suggest that higher temperatures increased and decreased the amylose content in HACV and LACV,respectively.Temperatures at 5-15 DAF were important for the formation of starch granules:lower temperatures during 10-14 DAF increased the proportion of larger starch granules(d>6.21μm,some with d>13.3μm),and higher temperatures at 5-6 DAF increased the proportion of starch granules with diameter 4.24-6.21μm.

Performance of Soft Rice (Oryza sativa L.) Grown in Early Season in China

Eating quality is of paramount importance to rice(Oryza sativa L.)consumers and soft rice with low amylose content has become popular in China.This study was conducted to evaluate the performance of soft rice grown in the early season(ES)dominated by non-soft rice.Field experiments were conducted in Yongan and Santang,Hunan Province,China from 2016-2018.Results showed that grain amylose content in soft rice cultivars was consistently lower in the ES compared to the late season(LS).The lower grain amylose content in the ES compared to the LS was partly attributed to higher average daily mean temperature during grain filling.No significant relationship was observed between grain yield and seed amylose content in ES rice.Soft rice cultivars produced a similar average grain yield to non-soft rice cultivars in the ES.These results encourage breeders to develop more ES rice cultivars with soft texture to meet the consumer demand for this type of rice.

Physiological Age Status of Female Adults and Off-Season Survival of Rice Leaffolder Cnaphalocrocis medinalis in India

Rice leaffolder, Cnaphalocrocis medinalis, is one of the major foliage feeders found in the rice growing regions in India. When the crop was at maturity, numerous adults of rice leaffolder were found in the rice fields though the larval population gradually decreased, and no eggs were found on rice leaves. The population characteristics of C. medinalis were assessed based on the physiological age status of adults at different crop growth stages. Based on egg development within ovarioles, ovariole appearance number and colour of fat bodies, and characteristics of bursa copulatrix, physiological age status of the adults was described, which served as a basis for the determination of age composition. C. medinalis adults were found during the first week of August on rice plants, of which 44% were in Age 0 with immature ovaries, indicating immigrants. However, 28% adults each were at Ages 1-2 with developing ovaries, indicating local breeding population. The carryover and off-season survival of C. medinalis were also studied to determine the contribution of the alternative hosts in the population growth that helped in devising efficient management strategies. Rice was the most preferred host followed by Triticum aestivum, Echinochloa crusgulli and Brachiaria plantaginea. Various routes of the carryover of C. medinalis from season to season were discussed.

Varietal and Seasonal Effect of Rice on the Physicochemical Properties of Rice Flakes

Rice-based flakes made from 7 mid-season rice varieties （4 indica and 3 japonica subspecies） and 3 early season indica varieties produced both in early and late season were studied for their main physicochemical characters, including water activity, film thickness, bulk density （BD）, ash, reducing sugars （RS）, protein, phytic acid, starch, amylose, and rapid visco analyser （RVA） viscosity profile. A significant varietal effect was found for all these parameters （P〈 0.05 or 0.01） except starch. Strong variety x season interactions were observed but the seasonal effect was less pronounced, and only significant （P〈0.01） for RS. The apparent amylose content （AAC） office flakes was significantly correlated （P〈0.01） with AAC （r=0.99） and several RVA profile parameters [e.g., final viscosity （r=0.92）] of rice flour. For rice flakes, BD was significantly correlated with AAC （r=0.82, P〈0.01） and most RVA profile parameters. The study indicates that varietal and environmental effects should be considered simultaneously for optimal production of rice grains for rice flakes manufacturing.

Development of High Yielding Aromatic Rice Variety BRRI dhan70 for Wet Season of Bangladesh

BRRI dhan70 is a new aromatic, high yielding and extra-long slender grain containing transplanted Aman rice variety which is an improvement over existing premium quality rice BRRI dhan37. BRRI dhan70 has pleasingly passed in the proposed variety trial conducted in the farmers’ field. As a result National Seed Board (NSB) approved this variety for commercial cultivation in the wet season (T. Aman) of Bangladesh in 2015. The important feature of BRRI dhan70 is the straw colored extra-long slender, higher elongation ability and aroma of the cooked rice. The growth duration of BRRI dhan70 is 130 days which is 10-15 days earlier growth duration than BRRI dhan37. Thousand grain weight of the variety is 20 gm and it has colored grain tip and pointed awn. The rice has 21.7% amylose content with 9.5% protein content. The special character of the variety is lodging tolerance. It has long, erect deep green flag leaf. BRRI dhan70 can produce 4.8-5.0 t/ha yield with proper management which is approximately 1.0-1.35 t/ha higher yield than BRRI dhan37. The exportable aromatic rice BRRI dhan70 is an excellent variety for cultivating in the wet (T. Aman) season and farmers can be benefited by the cultivation of BRRI dhan70.

Formula for Determining Number of Basic Seedlings at Scattered-Planting with Seedling Dry-Raised on Plastic Trays in Double-Season Rice

The tiller emergence in seedling nursery beds and field, and panicle formation in the field were investigated under scattered-planting with seedling dry-raised on plastic trays in double-season rice. A significant difference was noted in the non-synchronously-emerged tillers （the tillers that formed from latent buds and did not emerge following the normal tillering law on seedling nursery beds and recovered to grow after scattered-planting or transplanting） as well as the percentage of the available synchronously-emerged tillers between seedlings raised on plastic trays under dry-land conditions （DPT） and seedlings raised on nursery beds under wetland conditions （WB）. The seedlings under DPT had some non-synchronously-emerged tillers, but those under WB had not. Therefore, the traditional formula for determining the number of rice seedlings was improved, and the formula for determining the number of basic seedlings under scattered planting with DPT in double-season rice was introduced. For early rice, it was X=Y/{（I＋t1r1）[1＋（N-n-SN）Rr2]＋（SN-3-t1）R2r5}, and for late rice, it was X=Y/{（1＋t1r1）[1＋（N-n-SN）Rr2]＋（N-n-SN-3）Rr2R1r3＋（SN-3-t1）R2r5}. Where, X represents reasonable number of basic seedlings per unit area at scattered-planting; Y, number of fitting panicles per unit area; t1, total number of tillers per plant; r1, percentage of the total available tillers; N, total number of leaves of the main culm; n, total number of elongated internodes in the main culm; SN, seedling leaf ages at scattered-planting; R, percentage of the primary tillers emerged in available node-position; r2, percentage of the available primary tillers; R1, percentage of the secondary tillers in the field （except the secondary tillers of the seedlings）; r3, percentage of the available secondary tillers; R2, percentage of the asynchronously-emerged tillers after scattered-planting; r5, percentage of the available non-synchronously-emerged tillers after scattered-planting.

Impact of Agricultural Inputs on Groundwater Pollution in Off-Season Rice Farming in the Pic of Sindou Perimeter in Burkina Faso

Burkina Faso, an 80% agricultural country, today copes the massive use of agricultural inputs to boost productivity. However, these pesticides are sources of pollution of water resources. This is how, the objective of this work was to take stock of the inputs used on the Pic of Sindou rice perimeter and to characterize the vulnerability of the aquifer to these products. The study took place from February to September 2019, where two hundred farmers of the perimeter were investigated on the type and quantity of fertilizers and pesticides used in off-season rice farming activities. The DRASTIC method was used to map the vulnerability of the groundwater resource to these pollutants. Producers use NPK and Urea at 90% and 10% to the organic manure as fertilizers, and herbicides and insecticides with the actives ingredient are Glyphosate, Dimethoate and 2.4 D amine salt. The vulnerability to agricultural pollution of the aquifer remains low, but the risk of contamination from pesticides remains possible.

湖北漳河灌区中稻气象产量变化特征及预测模型

准确的气象产量是正确评估气象条件对粮食产量影响的前提。为了探究湖北漳河灌区单季稻气象产量的时间序列变化规律,尝试通过三点滑动平均法、HP滤波法和一次指数平滑法、二次指数平滑法4种方法将漳河灌区1975—2020年的水稻单产数据分离为水稻趋势产量及气象产量,通过相关分析筛选水稻8个生育阶段的主要气象因子,然后与分离的气象产量构建水稻预测模型。结果表明:4种分割方法均能较好地反映气象产量序列与湖北省生产力发展水平的区域一致性特点,多年平均气象产量占总产量的比例约为3.39%,但2008年以后其占比达到10.1%。相关分析识别出抽穗开花期最低气温、拔节孕穗期最高气温、分蘖后期平均气温、返青期最低气温、乳熟期蒸发量和育苗最低气温是影响气象产量的主要因子,该模型在率定期(1976—2014年)和验证期(2015—2020年)的相对误差均在5%以内,模型的决定系数R 2为0.994。预测模型有助于研究未来气候变化下的区域水稻产量的变化。

江汉平原典型种植模式稻田土壤中农药残留特征

在江汉平原中稻-油菜/小麦轮作田、一季中稻田及再生稻田3种种植模式稻田采集土壤样品86个。调查了土壤样品中滴滴涕(DDTs,包括o,p′-DDT、p,p′-DDT、p,p′-DDE、p,p′-DDD)、六六六(HCHs,包括α-HCH、β-HCH、γ-HCH、δ-HCH)、甲胺磷、甲基对硫磷、氧乐果、乐果、敌敌畏、乙酰甲胺磷、毒死蜱、氯虫苯甲酰胺、吡蚜酮、吡虫啉、啶虫脒、三环唑、戊唑醇、氰氟草酯、二氯喹啉酸、乙草胺及异丙甲草胺等25种农药及其代谢产物的残留。结果表明,检出率最高的3种农药为当前常用杀虫剂氯虫苯甲酰胺(87.21%),杀菌剂三环唑(91.86%)及戊唑醇(72.09%),其残留均值分别为0.0397、0.0734 mg/kg及0.0276 mg/kg;已经禁用的有机氯农药滴滴涕(o,p′-DDT、p,p′-DDT、p,p′-DDE、p,p′-DDD)仍能检出,检出率为36.05%~66.28%。3种模式田块中检出的滴滴涕主要来源于历史上滴滴涕的使用。杀虫剂吡蚜酮及杀菌剂三环唑在再生稻田的残留量均值显著高于中稻-油菜/小麦轮作田及一季中稻田;但其他农药在不同种植模式稻田中的残留没有显著差异。本研究为江汉平原农药残留的治理及农药的合理使用提供了参考信息。

“双季同种”水稻新品种松雅7号的选育与思考

“双季同种”是笔者根据湖南早晚稻生产和消费需求提出的育种设想,即在湖南同一个稻区,同一个品种通过早稻、晚稻“双审定”,且两季总生育期不超过220.0 d、两季总产量超过1000.0 kg/667 m^(2),早季米质达部标优质3级及以上,晚季米质达部标优质2级及以上。据此育成的水稻新品种松雅7号具有株型紧凑、茎秆粗壮、耐密植、芽期耐低温低氧能力较强等特点,在湖南省作早、晚双季稻种植生育期适宜、米质较好、丰产稳产,适宜机插、直播等轻简栽培。2023年通过湖南省早稻审定,2024年通过湖南省晚稻审定。本文介绍了松雅7号的选育经过和特征特性,及“双季同种”的概念、品种选育思路和具体要求,讨论了“双季同种”生产模式的实际意义。

单季稻开花结实期高温热害特征及防控对策

近年,长江流域稻区单季稻开花结实期高温频发重发。本文分析了高温年水稻开花结实期高温热害特征及高温对结实率的影响。高温年日最高温度高,持续时间延长;高温年7月上旬至8月上旬日最高温度较常温年高4.3℃~4.8℃;水稻开花结实期遇到高温热害结实率下降28.2~43.4个百分点;品种间耐高温热害特性差异较大。根据开花结实期高温热害特征及高温引起结实率下降的特点,提出高温预警及播期调整、耐热品种选择、高温期间田间灌水、喷施生长调节物质等开花结实期高温热害防控对策。

华南地区早晚兼用型水稻产量和氮素吸收在早、晚季的差异特征

为明确华南双季稻区早晚兼用型水稻产量和氮素吸收在早、晚季的差异特征,以6个早晚兼用型水稻品种为试验材料,按当地高产栽培条件在早、晚季种植,测定其产量、产量构成、干物质积累和氮素吸收等。结果表明,早晚兼用型水稻在早、晚季种植时产量分别为6.68~7.91 t/hm^(2)和5.72~6.11 t/hm^(2);早季产量显著高于晚季,平均增幅为1.53 t/hm^(2)。相关分析表明,较高的早季产量与其有效穗数和粒重的提高有关。早、晚季干物质积累量和氮素吸收差异显著;相对于晚季,早季成熟期干物质积累量和氮素吸收平均提高25.0%和29.5%。另外,早、晚季产量与其干物质积累量和氮素吸收显著正相关。早晚兼用型水稻在早季种植时具有较高的产量、物质生产和氮素吸收能力。研究结果可为华南地区早晚兼用型水稻的丰产栽培提供理论依据。

Simulation of Potential Productivity of Early Season Rice Varieties in Different Reqions of South China

Rice is a staple food crop in China.Since the 1950’s,many new varieties havebeen used and resulted in great increase ofyield.However there were still some barriersin the nationwide extension of new varietiesdue to the insufficient information about thecharacteristics of varieties.So,it is impor-tant to find ways of determining the potential

安徽省稻米品质综合评价方法研究

为定量化评价稻米品质综合性状,利用安徽省2008—2021年中籼和中粳水稻区域性试验稻米品质资料,根据食用稻品种品质行业标准,以整精米率、垩白度、透明度、碱消值、胶稠度、直链淀粉含量作为稻米品质评价指标,采用分级赋值、线性加权求和等方法以及计算机数值模拟技术,确定中籼和中粳稻米品质各项评价指标权重系数,并构建稻米品质指数(rice quality index,I_(RQ),中籼和中粳稻米品质指数分别用I_(RQ1)和I_(RQ2)表示)以及中籼和中粳稻米品质综合评价方法。结果表明,中籼稻米品质评价指标中整精米率、垩白度、透明度、碱消值、胶稠度、直链淀粉含量权重系数分别为0.20、0.26、0.06、0.22、0.10、0.16,中粳稻米中分别为0.23、0.28、0.10、0.08、0.15、0.16,其中垩白度是影响中籼和中粳稻米品质的主要因素。中籼优质稻米一至三等和普通稻米对应的稻米品质指数阈值分别为:I_(RQ1)≥3.94、3.94>I_(RQ1)≥3.47、3.47>I_(RQ1)≥3.17、I_(RQ1)<3.17,中粳优质稻米一至三等和普通稻米对应的品质指数阈值分别为:I_(RQ2)≥3.82、3.82>I_(RQ2)≥3.33、3.33>I_(RQ2)≥3.04、I_(RQ2)<3.04。经验证,构建的中籼和中粳稻米品质综合评价方法对于安徽省多品种样本检验的准确率分别为81.4%和80.0%,单品种样本检验的准确率分别为85.7%和92.9%;对于其他部分省份多品种样本检验的准确率均在80%以上,该方法可用于不同区域中籼和中粳稻米综合品质的定量化评价。