Varietal Difference in the Occurrence of Milky White Kernels in Response to Assimilate Supply in Rice Plants (Oryza sativa L.)

Abstract

We examined the association of assimilate supply in the occurrence of milky white kernels in three cultivars with different percentages of milky white kernels in the field condition: ‘Hatsuboshi’, ‘Koshiibuki’ and ‘Koshihikari’. Five days after heading, the plants were placed in four controlled-environment chambers with either a high or low night temperature and elevated or normal [CO₂] supply. Plants in each chamber were either defoliated with only flag leaf remaining, flag leaf and second leaf remaining or left intact (control). The percentage of each type of chalky kernel was examined. The percentage of milky white kernels was increased by defoliation and decreased by elevated [CO₂], associated with assimilate supply. No association was observed between assimilate supply and white back or basal white kernels. The percentage of milky white kernels was negatively correlated with assimilate supply at a high night temperature in all cultivars. At a low night temperature, there was a clear threshold of assimilate supply, over which the percentage of milky white kernels was nearly zero. Cultivar differences were observed in the relation between the percentage of milky white kernels and assimilate supply. In conclusion, we found a varietal difference in the occurrence of milky white kernels in response to assimilate supply. In the cultivars used in this study, ‘Hatsuboshi’ was more sensitive to the low assimilate supply than ‘Koshihikari’.     

Effects of Assimilate Supply and High Temperature during Grain-Filling Period on the Occurrence of Various Types of Chalky Kernels in Rice Plants (Oryza sativa L.)

Abstract

The objective of this study was to clarify the effect of assimilate supply and high temperature on the occurrence of chalky kernels, i.e. milky white, white back, basal white and white belly kernels. Rice cultivars Koshihikari and Takanari, contrasting in number of spikelets in a panicle were used. After heading, sink-source manipulation was imposed on plants, through changing supply of assimilates to spikelets by shading or panicle clipping. Plants with each sink-source manipulation were subjected to temperature treatments, i.e., high temperature and ambient temperature, using a temperature-gradient chamber. Percentage of various types of chalky kernels was examined with the treatment for each cultivar. High temperature treatment increased milky white and white back kernels while no significant effect of temperature was observed on the percentage of white belly and basal white kernels. Effects of sink-source manipulation on the occurrence of chalky kernels varied with the type of chalky kernels. Although sink-source manipulation had no effect on white back and basal white kernels, it had a significant effect on the percentage of milky white and white belly kernels, which indicates the association of assimilate supply with the occurrence of these types of chalky kernels. A close hyperbolic relation was observed between the rate of assimilate supply and the percentage of milky white kernels, suggesting that milky white kernels are caused by assimilate deficit during the initial half period of grain filling. The higher percentage of milky white kernels at a given rate of assimilate supply at a high temperature implied that the high temperature during the grain-filling period increases the assimilate demand to avoid the occurrence of milky white kernels. This is presumably because the high temperature during the grain-filling period accelerates grain growth especially in inferior spikelets.     

Morphological Evaluation of the Trace of Grain Detachment in Japonica Rice Cultivars with Different Shattering Habits

Abstract

Seed shattering is an important agronomic trait in rice as it directly affects the yield. Manipulation of the degree of shattering will maximize the yield potential. This study was performed to find an indicator for indirect selection to facilitate the selection of medium-shattering habit in japonica rice breeding. The grain shattering pattern and microscopic morphology of the separation zone on pedicels of five japonica rice cultivars with different shattering habits were compared. Almost all grains were separated between the sterile lemma and rudimentary glume in cultivars with medium-shattering, easily-shattering and very easily-shattering habits. On the other hand, approximately 50% of the grains of the cultivar with hardly-shattering habit were torn off at the bent portion of pedicel. A separation pileus was formed on the terminal of the pedicel. The pileuses were most prominent in cultivars with easily-shattering and very easily-shattering habits, while cultivars with a medium-shattering habit had more flat pileuses than prominent pileuses. Additionally, in the cultivar with a hardly-shattering habit all pileuses were flat. Development of fibrous cell walls on the separation pileus varied with degree of shattering habit. The easier the grain shattered, the poorer was the development of fibrous cell walls. These results strongly suggest that the shape of separation pileus and the development of fibrous cell walls are related to the shattering habit in japonica rice. Additionally, it is highly probable that the medium-shattering habit is characterized by the type of shattering that separates between sterile lemma and rudimentary glume with the flat shape of pileus.     

Differences in the Rate of Seedling Emergence among Rice Cultivars under Low Soil-Moisture Conditions

Abstract

The objective of this study was to identify rice cultivars with high emergence ability under low soil-moisture conditions using a large number of rice cultivars, and to clarify the differences between the rates of emergence in lowland and upland, white- and red-kerneled, and non-glutinous and glutinous cultivars. First, 30 cultivars with a high emergence rate at 14 days after sowing (DAS) were selected at a soil water potential of -1.17 to -0.89 MPa from 382 cultivars through fourscreening experiments. In these experiments, the emergence rate was significantly higher in the upland cultivars than in the lowland cultivars. The red-kerneled cultivars also had a significantly higher emergence rate than the white-kerneled cultivars. However, no difference in emergence rate was observed between the non-glutinous and glutinous cultivars. Second, the emergence rates of various cultivars were examined at a soil water potential of -1.62, -1.23, and -1.07 MPa. The higher the soil water potential, the higher the emergence rate at 28 DAS and the shorter the time to the emergence. The order of cultivars in their emergence rate at 13 DAS at -1.07 MPa was similar to that at 28 DAS at -1.62 MPa. Therefore, the dataat 13 DAS at -1.07 MPa were used to compare the selected 30 cultivars for their emergence ability under low soil-moisture conditions. Moulla Topa showed the highest emergence rate (78.1%) and Gaiya Rate Bhasunamathe the shortest time to 50% emergence (11.1 d) under these conditions.     

Effect of High Temperature at Ripening Stage on the Reserve Accumulation in Seed in Some Rice Cultivars

Abstract

The resistance to high-temperature stress and the structural appearance of the imperfect grains caused by a high temperature at the ripening stage were studied using 13 selected cultivars of rice. High temperature treatment (daily maximum temperature range, 32-40°C) given from the 4th day after heading caused the decrease in panicle weight in all of the cultivars examined. The number of empty grains in the upper and lower parts of a panicle was increased by the high temperature in 10 cultivars. Cultivars KRN, Citanduy, Belle patna and BPB were tolerant to the high-temperature treatment at the ripening stage, and cvs. Koshihikari, Sanlicun, Tainung 67, Yamada-nishiki and Lady Wright were sensitive. Light microscopic observation showed that, the whole endosperm was covered with a nucellar epidermis (NE) under both high and natural temperature (26-31°C) conditions at the first week after heading (WAH). Under high-temperature conditions the NE degenerated earlier than under natural temperature conditions. Scanning electron microscopic observation showed that, the endosperm cells of the seeds with a specific gravity (s.g.) of higher than 1.06 had large amyloplasts filled with starch granules. However, the endosperm cells of seeds with a s.g. of 1.00-1.06 had many small amyloplasts containing small single starch granules and had numerous spaces among the amyloplasts. In the endosperm cells at the dorsal side of imperfect grain, layered structures showing progressive decomposition of starch granules were observed.     

水稻产量对生殖生长阶段不同时期高温的响应差异

[目的]研究水稻产量对不同时期不同类型高温的响应差异,为耐热水稻品种的筛选与培育提供依据.[方法]在桶栽条件下,于人工气候室内,以耐热水稻品种Nagina 22、汕优63和热敏感品种两优培九为材料,设置三个处理时期,即穗分化期、开花期和灌浆期;四种处理温度,即白天高温、夜间高温、全天高温和适宜温度,研究水稻产量和产量构...     

红壤稻田钾肥施用量对超级稻生长及产量的影响

 以超高产水稻中浙优1号、甬优9号为材料,研究土壤不同钾素水平(50 mg/kg、90 mg/kg)及钾肥用量(0、75、150、225 kg/hm2氯化钾)对水稻生长和产量的影响。土壤不同钾素水平对穗数、成穗率、每穗粒数、着粒密度、株高、叶片叶绿素含量（SPAD值）和光合速率有显著影响,差异达显著水平;不同时期施用钾肥对产量的贡献依次为：基肥>分蘖肥>穗肥,产量差异达到3%~10%;随着施钾量增加植株高度明显增加,中浙优1号上表现更为明显,且随着施钾量增加,茎秆加粗,特别是基部节间粗度增加尤为明显。施钾与不施钾相比,两个品种产量分别增加5.6%和8.8%,但产量增加并不与施钾量成正比,不同施钾水平间产量差异不显著。     

高AC水稻淀粉合成相关酶基因表达的温度效应

以高直链淀粉含量(AC)早籼稻品种嘉育353为材料,利用人工气候箱设置高温(日均温32℃)和适温(日均温22℃)2个温度处理,采用实时荧光定量PCR技术分析了不同灌浆温度下水稻胚乳中3个淀粉分支酶基因(sbe1、sbe3和sbe4)、3个淀粉脱支酶基因(R酶基因、isa1和isa2)以及2个淀粉合酶(GBSSⅠ和SSSⅠ)基因的表达特性。结果显示,除了sbe4、isa1和GBSSⅠ基因外,其余基因高温下表达量均显著高于适温,表明sbe1、sbe3、R酶基因、isa2以及SSSⅠ基因属于温度敏感型基因,可能在水稻胚乳淀粉合成的温度调控方面起着关键作用。     

Effects of High Temperature on Growth,Yield and Dry-Matter Production of Rice Grown in the Paddy Field

Abstract

The effect of high temperatures on growth, yield and dry-matter production of rice growing in the paddy field was examined during the whole growth period in a temperature gradient chamber (TGC) from 2002 to 2006. Experimental plots, TG1 (control), TG2, TG3 and TG4, were arranged along the temperature gradient (from low to high temperature) in TGC. The mean and maximum air-temperatures in TG4 were 2.0 –3.6ºC and 4.0º7.0ºC higher, respectively, than those in TG1. The plant height was taller and the maximum tillering stage was earlier in TG2, TG3 and TG4 than in TG1. Plant dry weight at maturity in TG2 and TG3 was 12.8?16.4% heavier than that in TG1. In TG4, the increase in the panicle dry weight during the ripening period was smallest and plant dry weight at maturity was 11–16% heavier than that in TG1. The increase in plant dry-matter during the ripening period was smallest in TG4. The decrease in the dry weight of stem and leaf during the ripening period, which represents the amount of assimilate translocation to the panicle, was also larger in TG2-4 than in TG1. The increase in the dry weight of stem in TG2-4 at maturity was also larger than that in TG1. The photosynthetic rate in TG2-4 was up to 35.6% lower than that in TG1 because of the acceleration of leaf senescence. Brown rice yield in TG4 was 6.6?39.1% lower than that in TG1. This yield decline was due to the decrease in the percentage of ripened grains and increase in the percentage of sterile spikelets. The relation between brown rice yield and mean air-temperature during 20 days after heading showed that the brown rice yield declined when mean air-temperature exceeded 28ºC.     

高温和肥水调控对川东南杂交水稻结实率的影响

以5个杂交中稻组合为材料,在智能人工气候室条件下,研究了极端高温对杂交中稻结实率的影响与肥水调控效果.结果 表明,孕穗期和抽穗期日均温33℃以上对结实率的影响显著,38℃以上时结实率急剧下降,抽穗期遇38℃高温,参试品种的结实率均在10％以下;孕穗期受高温影响明显比抽穗期小,33℃条件下,孕穗期高温产量损失在10％以内...     

孕穗期低温胁迫下不同磷营养对水稻生长发育影响的研究

以不同耐冷性品种吉粳81和长白9为供试材料,进行不同的磷肥施用量处理（施入磷酸二铵分别为0、40、80、120和160 kg/hm2）,对孕穗期低温胁迫下不同磷营养对水稻株高、穗抽出度、穗长、结实率以及单穴产量进行研究。结果表明,低温胁迫会抑制吉粳81和长白9植株生长,导致穗抽出度、穗长、结实率以及产量下降,且对非耐冷...     

不同播栽方式下杂交籼稻茎秆生长和穗粒形成特点及与气象因子的关系

为探明不同播栽方式下杂交籼稻幼穗分化期茎秆和幼穗生长的规律及差异以进一步明确不同播栽方式穗粒形成特点,于2014年采用两因素裂区试验设计,研究了机直播、机插和手插3种播栽方式下2个不同穗粒型杂交籼稻组合[宜香优2115(中穗型)和F优498(大穗型)]的穗分化期茎秆和幼穗生长规律和穗粒形成特点,并分析了幼穗分化期气象因素与幼穗和茎秆生长的关系。结果表明:1)基部向上第1至第3伸长节间长度分别在抽穗前20d、16d、12d后趋于稳定,故基部第1、2节间的降长增粗应在抽穗前16d之前;穗干质量和穗茎比在抽穗前12d后迅速增加。2)从抽穗前16d开始至抽穗期,穗茎干重比与多数枝梗和颖花性状呈显著或极显著正相关,穗与茎秆竞争同化物的能力直接影响到穗粒形成。3)机插穗分化中后期穗茎干质量比较高,且抽穗期穗干质量显著高于手插和机直播,有利于提高其每穗粒数,且机插拔节后群体生长率及单茎和群体干物质积累量较高,抽穗期叶面积指数较高,粒叶比高于机直播,较机直播更利于粒重的提高和穗长及着粒数的增加;大穗型品种F优498抽穗期穗干质量显著高于中穗型品种宜香优2115,且穗分化后期穗茎干质量比高于宜香优2115,是其每穗粒数高的重要原因;F优498穗部着粒较密,较大的叶面积指数及粒叶比利于大穗的形成。4)机插全生育期最长,机直播最短,且机插穗分化期历时较长,穗分化期积温和日照时数较高,为穗粒形成提供了较好的温光条件;茎秆长度和干质量及穗长受气象因子影响较大,孕穗前适宜的温度和一定的积温有利于茎秆和幼穗伸长及茎秆的物质充实。生产上应针对不同播栽方式及品种的生育进程差异,适时采取措施调节茎秆和幼穗生长及物质分配,在培育壮秆的基础上提高穗分化期穗茎比以达到增粒增产的目的。     

Effect of High Temperature on Sucrose Content and Sucrose Cleaving Enzyme Activity in Rice Grain During the Filling Stage

Global warming is due to continuous increase in greenhouse effect caused by human productive activities. Much attention has been paid to the influence brought by the increase of temperature on crop growth. Many researches in China and other countries are …     

Changes in NMR Relaxation of Rice Grains,Kernel Quality and Physicochemical Properties in Response to a High Temperature after Flowering in Heat-Tolerant and Heat-Sensitive Rice Cultivars

Abstract

Rice productivity is related to the ability of plants to adapt to heat stress. The heat-tolerant cultivars ‘Nikomaru’ and ‘Chikushi 64’ and heat-sensitive cultivar ‘Hinohikari’ were grown at 30ºC and 25ºC for 49 days after flowering. At 30ºC, only a few white immature kernels were produced in ‘Nikomaru’ and ‘Chikushi 64’, but about 22% of grains had immature kernels in ‘Hinohikari’. The high temperature(30ºC) caused no significant changes in grain dry weight, water content, and the NMR T₁ value during the early ripening stage in ‘Nikomaru’ and ‘Chikushi 64’. It also did not affect grain development, especially with respect to the nucellar epidermis, in ‘Nikomaru’ and ‘Chikushi 64’, but caused clear cessation of development of the nucellar epidermis at 14 days after flowering in ‘Hinohikari’. In addition, high temperature decreased the amylose content and increased hardnessvs. adhesion ratio of cooked rice in both ‘Nikomaru’ and ‘Chikushi 64’ resulting a softer, less sticky texture, but not in ‘Hinohikari’. The maximum viscosity and breakdown values were increased, and final viscosity decreased at 30ºC in all three cultivars. These results suggested that starch in the endosperm of grains changed from a fluid state to a doughy state more slowly in ‘Nikomaru’ and ‘Chikushi 64’ than in ‘Hinohikari’, in which the water content and NMR relaxation time decreased, and transported assimilates accumulated slowly during grain development.     

生育后期断水时间和收割日期对优质水稻产量及品质的影响

以南粳9108为试验材料,设计3个断水时间(齐穗后29、34、39 d)、3个收割日期(齐穗后45、50、55 d),共设置9个处理。结果表明,南粳9108齐穗后39 d左右断水,55 d开始收割,可以保证加工品质、外观品质。说明断水期提前,前期可以促进水稻籽粒灌浆,但最终的收获产量降低;断水过早会造成水稻糙米率降低,而土壤水分充足的情况下,收割日期对糙米率无明显影响。收割日期对垩白粒率、垩白度影响显著,收割过早,垩白粒率、垩白度高,外观品质差。     

A Varietal Difference in Coleoptile Growth is Correlated with Seedling Establishment of Direct Seeded Rice in Submerged Field under Low-Temperature Conditions

Abstract

To elucidate the physiological characteristics relating to better seedling establishment in submerged field under low-temperature conditions, we compared the time required to reach various growth stages after seed imbibition among rice {Oryza sativa L.) varieties differing in the performance of seedling establishment. Two experiments were conducted. In the field experiment, the percentage of seedlings with expanded second leaf at 30 days after sowing (PSSL) was measured and regarded as the index of establishment rate for each variety. In agar-bed experiment, the number of germinated seeds, the seedlings with the coleoptile elongated to the medium surface, and the seedlings with the 1st leaf apparent were counted daily under a 16°G condition. A sigmoid model was applied to the above values to evaluate the time requirements. There was a significant correlation between the duration from 50% germination to 50% emergence in the agar-bed experiment and PSSL in the field experiments. However, the duration from imbibition to 50% germination, and that from 50% emergence to 50% appearance of the first leaf were not significantly correlated with PSSL. We found that fast growth of the coleoptile is an important characteristic for the varieties that can provide stable and excellent seedling establishment at low temperature.     

四川盆地东南部杂交中稻开花期高温伤害的风险预测

准确预测不同区域杂交中稻开花期与自然极端高温发生期相遇的概率,有利于制定当地水稻生产避险高产稳产技术。以四川省推广的22个杂交中稻新品种为材料,在四川盆地东南部不同生态点开展品种生态适应性试验,研究了基于经度、纬度和海拔高度的杂交中稻开花期受自然极端高温伤害风险的预测方法。结果表明,杂交中稻齐穗后第5天日序与经度呈显著负相关,与海拔高度呈极显著正相关,与纬度相关性不显著。建立的基于经度（x₁）和海拔（x₃）预测水稻齐穗后第5天日序的回归模型,F值为13.25^**~13.56^**,决定程度高达0.8688~0.8715。该模型经多个品种连续2年在6个生态点的验证,实测值与预测值1∶1回归模型的决定系数高达0.8362~0.8641,实测值与预测值之间的均方根差（RMSE）值为0.83%~1.18%,预测值与实测值之间具有较好的一致性。将本研究建立的齐穗期与地理位置关系模型与作者等先期建立的基于地理位置（纬度：x₂、海拔：x₃）预测≥35℃最早发生期预测模型相结合,探明了不同地理位置杂交中稻开花期受极端高温伤害的机率。利用地理位置信息可准确预测杂交中稻开花期受极端高温伤害的风险程度,具有较好的生产适用性。     

水稻亚种间杂种F1的光温反应特性与其亲本遗传关系的初步研究

对１８个水稻亚种间杂种及其２１份亲本材料进行了光温反应测定，分析了Ｆ１与其亲本的遗传关系。结果表明：亚种间杂种的感光性强和短日高温生育期短表现为超显性遗传或显性遗传；感温性的遗传关系比较复杂。并从光温反应特性的角度对我国主要稻区亚种间杂交水稻组合选育的亲本配组模式进行了讨论。     

Difference in Growth Characteristics,Utilization of Temperature and Illumination of Double- Cropping High Quality Late Rice in Different Ecological Regions of the Lower Reaches of the Yangtze River

【Objective】Under machine-transplanting conditions, four different types of late rice cultivars with high quality were used to investigate the differences of yield, growth characteristics, utilization of temperature and illumination. The results will lay a theoretical basis for the selection of double-cropping late rice varieties suitable for different ecological regions in the lower reaches of the Yangtze River.【Method】The yield, growth duration, dry matter accumulation, and utilization of temperature and illumination of double-cropping late rice were comparatively studied using four kinds of rice varieties as test materials namely indica conventional rice, indica hybrid rice, japonica conventional rice and Changyou japonica hybrid rice (20 varieties in total, selected between 2016 and 2017, all of which were high-quality rice in the lower reaches of the Yangtze River as double-cropping late rice). The experiment was carried out in two cities, Fuyang, Zhejiang Province (30.05º N, 119.95º E, 17.93 m above sea level) and Lujiang, Anhui Province (31.15º N, 117.16º E, 14 m above sea level).【Result】The yield of the four-types of late rice at high latitude was higher than that at low latitude. The yield of indica conventional rice, indica hybrid rice, japonica conventional rice, and Changyou japonica hybrid rice grown in Lujiang, Anhui Province was 11.1%, 12.9%, 6.6% and 12.4% higher than that in Fuyang, Zhejiang Province. When planted in the same places, Changyou japonica hybrid rice had the highest yield, and conventional indica rice had the lowest. The growth period was longer and dry matter accumulation was higher at high latitudes. When planted at high altitudes, the indica hybrid rice growth duration was the longest (10.4 d), and the increase in dry matter accumulation was the largest in conventional japonica rice (11.93% in full heading stage and 9.44% in mature stage). When planted in the same place, the dry matter accumulation was higher in hybrid rice than conventional rice. There was no significant difference in effective accumulated temperature between the filling stage and the whole growth duration of indica rice, but the sunshine hours, solar radiation, and its utilization rate were significantly higher at high latitudes. The effective accumulated temperature decreased significantly in the filling stage and the whole growth stage of japonica rice, but the change of accumulated sunshine hours was not obvious, while the accumulated solar radiation increased significantly at high latitudes. These were consistent with the changing trend of the utilization rate of the temperature and light resources. When planted at the same latitude, the growth period, dry matter accumulation, temperature and light resource utilization rate of japonica rice were higher than those of indica rice.【Conclusion】Late indica rice could make full use of temperature and light resources in order to improve its yield when planted in Lujiang, Anhui Province, but the difference of the utilization efficiency in the temperature and light resources of late japonica rice was not obvious. The yield of late japonica rice in Lujiang, Anhui Province increased because of the extension of the growth duration and the increase of dry matter accumulation.