长粒香型的超短生育期水稻新品系创制

培育优质、超短生育期的水稻品种对提高长江中下游地区复种指数,保障我国粮食安全具有重要意义。本研究以超短生育期水稻品系CPPC09-180-28-1-5为母本,携带香味基因fgr和粒长基因GW7的优质水稻品种象牙香占为父本,通过杂交、回交并结合全基因组分子标记辅助选择技术培育了3个携带纯合fgr和GW7基因的优质、超短生育期水稻新品系。对新育成品系进行香味鉴定、主要农艺性状考察及稻米品质分析。结果表明,导入fgr和GW7基因的新品系具有明显香味,粒长较受体CPPC09-180-28-1-5显著增长,品质较优。新品系的全生育期85~98 d,与受体CPPC09-180-28-1-5基本一致,可作早稻或晚稻在长江中下游稻区进行种植,提高复种指数。此外,新育成品系在株高、千粒重以及单株产量等性状较受体CPPC09-180-28-1-5有显著减小,表明本研究中携带目标基因的2个染色体片段导入对受体CPPC09-180-28-1-5的主要农艺性状具有显著的影响。本研究可为优质、超短生育期的水稻分子育种提供种质资源和育种策略。

稻油系统周年产量差及形成因素探究: 以湖北省武穴市为例

明确农户水平稻油系统的产量差及进一步增产的限制因素对保障我国粮油安全具有重要作用。本研究以我国典型稻油系统生产区湖北省武穴市为研究对象,采用作物模型与田间调查相结合的方法评估了该地区稻油系统周年产量差,并使用单因素方差分析和条件推断树综合比较了农户在土壤条件和管理措施上的差异,以探究该地区限制稻油系统产量进一步增长的主要栽培因素及可行的增产途径,为因地制宜地缩小产量差提供新思路。结果表明:(1)武穴市水稻季和油菜季的潜在产量分别为11.79 t hm^(-2)和4.43 t hm^(-2),按照水稻和油菜籽粒的能量当量换算系统周年能量后,稻油系统的最高周年潜在能量为284 GJ hm^(-2)。水稻季和油菜季的平均实际产量分别为8.11 t hm^(-2)和1.82 t hm^(-2),系统平均实际周年能量为165 GJ hm^(-2)。该地区稻油系统的平均周年相对产量差(产量差与潜在产量的比值)为42%,其中油菜季(59%)比水稻季(31%)具有更大的产量提升空间。相较于湖北省和长江流域的平均水平,武穴市稻油系统周年潜在能量相近,而周年实际能量分别低13%和5%,导致该地区的产量差相对较大,其中分别有83%和61%的农户相对产量差大于湖北省和长江流域平均水平。(2)该地区周年产量较低的农户具有以下主要特征:土壤为沙壤土,耕层较浅;水稻季虫草害防治效果差,水稻季肥料做底肥一次施用且轻施氮、钾肥;油菜季重施肥料,且油菜机收损失较大。(3)武穴市89%的农户选择种植常规稻品种黄华占,其实际产量已达到该品种潜在产量的90%左右;种植油菜品种的种类较多且产量差异较大。综上,武穴市稻油系统仍具有较大的增产空间;缩小当地稻油系统产量差的技术措施包括:适当深耕提高土壤生产力;油菜季选择当地适宜的高产油菜品种;水稻季加强推广高产优质杂交稻品种,重点关注增加水稻用种量,提高直播密度和播种时的封闭除草,系统周年施肥管理上应降低油菜季而提高水稻季的肥料用量,水稻季仅施底肥的农户适当增施追肥等。

氮磷钾配方施肥对核桃产量和品质指标的影响

研究氮(N)、磷(P)、钾(K)配方肥对核桃产量及品质的影响,为核桃施肥提供依据。以7年生早实核桃"辽核4号"为试验材料,于核桃萌芽期、幼果发育期和硬核期进行施肥,在果实采收前调查产量并进行果实养分测定,研究不同配方肥对核桃产量及品质的影响。结果表明,不同N、P、K施肥处理对核桃单位冠幅产量、单果重、出仁率影响显著,对饱和脂肪酸含量、不饱和脂肪酸含量、蛋白质含量、脂肪含量影响不显著。处理1的单位冠幅产量、单果重、亚油酸含量最高,其施肥量:N为345g/株、P为345g/株、K为345g/株,施肥比例为N∶P∶K=1∶1∶1,水平组合为N1P2K2。处理4的出仁率、不饱和脂肪酸和蛋白质含量最高,其施肥量:N为690g/株、P为345g/株、K为0g/株,施肥比例为N∶P∶K=2∶1∶0,水平组合为N2P2K0。处理7脂肪含量、亚麻酸含量最高,其施肥量:N为690g/株、P为172.5g/株、K为172.5g/株,施肥比例为N∶P∶K=4∶1∶1,水平组合为N2P1K1。N肥与单位冠幅产量、亚麻酸含量呈显著正相关;P肥与出仁率呈显著正相关,与各品质指标相关性不大;K肥与单位冠幅产量呈显著正相关,与不饱和脂肪酸呈显著负相关。

配方施肥对早实核桃品种辽核4号蛋白质和脂肪含量影响的研究

以早实核桃辽核4号初果期树为研究材料,采用N、P、K"3414"最优回归设计方案,研究了配方施肥对于核桃总蛋白和总脂肪含量的影响。研究发现配方施肥可以明显地提高核桃总蛋白和总脂肪的含量,且N、P、K施肥量与核桃总蛋白和总脂肪含量均符合三元二次回归方程的肥料效应函数规律。通过肥料效应函数分析得出能有效提高核桃总蛋白和总脂肪含量的施肥范围为N施用量在869.31~1 082.01g/株,P_2O_5施用量在513.26~522.50g/株,KO_2施用量在434.65~504.65g/株。研究结果为关中台田上通过配方施肥提高核桃果实的品质提供了理论依据。

高管股权激励与公司异常关联交易:抑制还是加剧

从高管股权激励是否能够抑制有损公司价值的行为视角,分析和检验高管股权激励对异常关联交易的影响及其作用机制。为了克服选择性偏误,采用双重差分倾向得分匹配法(PSM-DID)进行实证检验,研究结果显示高管股权激励与异常关联交易之间呈显著的负向关系,表明中国上市公司的高管股权激励抑制了异常关联交易,从而支持最优契约理论;截面分组发现高管股权激励对异常关联交易的抑制作用仅在公司治理水平较低的组显著;机制检验发现高管股权激励促使高管有强烈的动机提升公司业绩,进而抑制有损公司价值的异常关联交易行为。该结果验证了我国上市公司高管股权激励的实施效果符合最优契约理论而非管理层权力理论的推论,为证监会推行股权激励提供了经验证据。

光对水稻非光合组织谷氨酰胺合成酶同工酶表达的影响(英文)

以前的研究表明 ,高等植物叶绿体谷氨酰胺合成酶 (GS2 )受光调节 ,但叶片胞液 GS(GS1 )和非光合作用组织中的 GS很少受光的影响。在本报道中 ,笔者运用 GS活性染色和Western blotting研究了光对非光合作用组织水稻根 GS同工酶表达的影响。在阳光的直接照射下以及在室内不同光照强度下 ,可以很清楚地观察到 GSra和 GSrb的活性带及其蛋白质带。但是 ,当用尼龙网挡住阳光的直接照射时 ,GSrb的活性带和蛋白质带消失 ;当阳光被尼龙网遮挡住后 ,其光强度仍然比室内光照强度大得多 ,表明光照强度不是影响 GSrb表达的主要因素。当分析生长在暗处以及生长在光 /暗转换下的水稻幼苗根 GS同工酶变化时 ,仍然可以观察到 GSrb的存在。在所有实验条件下 ,GSra都未发生明显变化。这些结果提示 。

23个水稻品种作再生稻比较试验结果及评价

以23个不同类型的水稻(Oryza sativa L.)品种为材料进行再生稻比较试验,主要从品种生育期、产量、品质、抗性4个方面进行了综合比较分析。结果表明,华两优2882、旱优73、华两优2834、天两优616、华两优2881、新两优223、黄科香1号、黄科香2号共8个品种适合作为再生稻种植。

达州站解编系统能力扩能探讨

为适应铁路货运组织改革与提升铁路运输时效性,研究结合达州区段站运输生产实际,分析车站列车到发及解编系统通过能力,统筹考虑车站站型布置及相邻路网技术作业站的改造,并采用计算分析法确定制约车站能力的关键因素。在此基础上,结合研究年度内预测车站工作量,以尽量避免大拆大改工程提高车站能力为出发点,提出切实可行的车站扩能改造方案,以期匹配点线能力,提高车站作业效率,满足路网运输需求,为川东北地区加快融入川渝经济圈及长江经济带的建设提供技术保障,同时为铁路技术作业站的改造提供技术参考。

Yield potential and nitrogen use efficiency of China's super rice

In 1996, a mega project that aimed to develop rice varieties with super-high yield potential （super rice） was launched by the Ministry of Agriculture （MOA） in China using a combination of the ideotype approach and intersubspecific heterosis. Significant progress has been made in the last two decades, with a large number of super rice varieties being approved by the MOA and the national average grain yield being increased from 6.21 t ha^-1 in 1996 to 6.89 t ha^-1 in 2015. The increase in yield potential of super rice was mainly due to the larger sink size which resulted from larger panicles. Moreover, higher photosynthetic capacity and improved root physiological traits before heading contributed to the increase in sink size. However, the poor grain filling of the later-flowering inferior spikelets and the quickly decreased root activity of super rice during grain filling period restrict the achievement of high yield potential of super rice. Furthermore, it is widely accepted that the high yield potential of super rice requires a large amount of N fertilizer input, which has resulted in an increase in N consumption and a decrease in nitrogen use efficiency （NUE）, although it remains unclear whether super rice per se is responsible for the latter. In the present paper, we review the history and success of China＇s Super Rice Breeding Pro- gram, summarize the advances in agronomic and physiological mechanisms underlying the high yield potential of super rice, and examine NUE differences between super rice and ordinary rice varieties. We also provide a brief introduction to the Green Super Rice Project, which aims to diversify breeding targets beyond yield improvement alone to address global concerns around resource use and environmental change. It is hoped that this review will facilitate further improvement of rice production into the future.

Effect of Nitrogen Regimes on Grain Yield,Nitrogen Utilization,Radiation Use Efficiency,and Sheath Blight Disease Intensity in Super Hybrid Rice

Poor nitrogen use efficiency in rice production is a critical issue in China. Site-specific N managements （SSNM） such as real-time N management （RTNM） and fixed-time adjustable-dose N management （FTNM） improve fertilizer-N use efficiency of irrigated rice. This study was aimed to compare the different nitrogen （N） rates and application methods （FFP, SSNM, and RTNM methods） under with- and without-fungicide application conditions on grain yield, yield components, solar radiation use efficiency （RUE）, agronomic-nitrogen use efficiency （AEN）, and sheath blight disease intensity. Field experiments were carried out at Liuyang County, Hunan Province, China, during 2006 and 2007. A super hybrid rice Liangyou 293 （LY293） was used as experimental material. The results showed that RTNM and SSNM have great potential for improving agronomic-nitrogen use efficiency without sacrificing the grain yield. There were significant differences in light interception rate, sheath blight disease incidence （DI） and the disease index （ShBI）, and total dry matter among the different nitrogen management methods. The radiation use efficiency was increased in a certain level of applied N. But, the harvest index （HI） decreased with the increase in applied N. There is a quadratic curve relationship between grain yield and applied N rates. With the same N fertilizer rate, different fertilizer-N application methods affected the RUE and grain yield. The fungicide application not only improved the canopy light interception rate, RUE, grain filling, and harvest index, but also reduced the degree of sheath blight disease. The treatment of RTNM under the SPAD threshold value 40 obtained the highest yield. While the treatment of SSNM led to the highest nitrogen agronomic efficiency and higher rice yield, and decreased the infestation of sheath blight disease dramatically as well. Nitrogen application regimes and diseases control in rice caused obvious effects on light interception rate, RUE, and HI. Optimal N rate is helpful to get higher light interception rate, RUE, and HI. Disease control with fungicide application decreased and delayed the negative effects of the high N on rice yield formation. SSNM and RTNM under the proper SPAD threshold value obtained high-yield with high efficiency and could alleviate environmental pollution in rice production.

Comparisons of Yield and Growth Behaviors of Hybrid Rice Under Different Nitrogen Management Methods in Tropical and Subtropical Environments

To compare the grain yield and growth behaviors of hybrid rice, field experiments were conducted in a subtropical environment in Changsha, Hunan Province, China, and in two tropical environments in Gazipur and Habiganj in Bangladesh during 2009 to 2011. Three hybrid rice cultivars were grown under three nitrogen （N） management treatments in each experiment. The results showed that grain yield was significantly affected by locations, N treatments and their interaction but not by cultivars. Changsha produced 8-58% higher grain yields than Bangladesh locations. Sink size （spikelet number per unit land area） was responsible for these yield differences. Larger panicle size （spikelet number per panicle） contributed to greater sink size in Changsha. Aboveground total biomass was greater in Changsha than in Bangladesh locations, whereas harvest index was higher in Bangladesh locations than in Changsha. Crop growth rate （CGR） was greater at Changsha than Bangladesh locations during vegetative phase, while the difference was relatively small and not consistent during the later growth phases. Higher leaf area index and leaf area duration were partly responsible for the greater CGR in Changsha. Real-time N management （RTNM） produced lower grain yields than fixed-time N management in more than half of the experiments. Our study suggested that further improvement in rice yield in the tropical environments similar to those of Bangladesh will depend mainly on the ability to increase panicle size as well as CGR during vegetative phase, and the chlorophyll meter threshold value used in RTNM needs to be modified according to environmental conditions and cultivar characteristics to achieve a desirable grain yield.

陕西野生兰科资源分布特征及保护策略

陕西省野生兰科植物资源丰富,我国大多数兰科植物生长北线即在陕西秦岭。长期以来野生兰科植物资源受人为破坏、气候变化等影响,生存受到严重威胁。本文在实地调查及查阅文献资料基础上,分析研究了陕西省野生兰科植物分布区域特征、海拔高度及立地条件,提出了陕西省内野生兰科资源保护策略,包括建立种质资源库、开展就地保存和迁地保护,建立种质繁殖基地、加强兰科资源繁育技术研究等。

Grain yield and lodging-related traits of ultrashort-duration varieties for direct-seeded and double-season rice in Central China

Lodging is the most common constraint on grain yield of direct-seeded rice.There is limited information about lodging resistance and its related plant traits in direct-seeded and double-season rice(DDR)in Central China.This study aims to identify the plant traits that achieve high lodging resistance in ultrashort-duration varieties(about 95 days)of DDR.Field experiments were conducted in 2017 and 2018 in Wuxue County,Hubei Province,China,with four ultrashort-duration varieties grown under two nitrogen(N)rates.Lodging-related traits were measured on the 15 th day after heading,and yield and yield attributes were measured at maturity.The grain yield of the four varieties ranged from 4.59 to 7.61 t ha^(-1)across the two N rates,with a total growth duration of 85 to 97 days.Varietal differences in lodging index were mainly explained by the bending moment,which was closely related to plant height.Breaking resistance did not affect the lodging index significantly.Shortening plant height from 95.4 to 80.5 cm decreased the lodging index by 22.4%but did not reduce grain yield.Our results suggested that reducing plant height was effective in improving the lodging resistance of ultrashort-duration varieties of DDR.Lodging resistance should be enhanced by improving breaking resistance rather than reducing plant height to increase DDR grain yield further.

Booming research on rice physiology and management in China： A bibliometric analysis based on three major agronomic journals

Rice research has always been the top priority in China and China produces the highest number of scientific journal papers on rice, particularly on rice genetics and breeding. In this study, we used a bibliometric approach to analyze the trends of papers published by Chinese researchers on rice physiology and management. Data were collected from three major agronomic journals（i.e., Agronomy Journal, Crop Science, and Field Crops Research） by searching in the Web of Science on September 8, 2017. A total of 186 rice papers were published by Chinese researchers on crop physiology and management in the three journals since their establishment. Yearly average number of such papers was 1.6, 6.5, and 21.0 for the periods of 1993–2005, 2006–2011, and 2012–2017, respectively. Their quality in terms of citation performance has also improved significantly in the recent decade. Huazhong Agricultural University, Yangzhou University, and Nanjing Agricultural University were leading organizations and published 54.4% of all 186 papers. Huang Min of Hunan Agricultural University and Peng Shaobing of Huazhong Agricultural University published the most number of rice papers on crop physiology and management as the first and corresponding authors, respectively. Yield potential and nitrogen-related research such as nitrogen use efficiency, nitrogen management, and plant nitrogen diagnosis have been the research focuses for rice crop. In recent years, research on global warming including high temperature stress, direct seeding, zero tillage, Bt rice, and critical nitrogen dilution curve were becoming popular. New research is emerging on yield gap, rice ratooning, and simplified and reduced-input practices in rice production.

Effects of nitrogen management on the ratoon crop yield and head rice yield in South USA

Ratoon rice cropping is an important component of the rice cropping system in Texas and south Louisiana,USA,and expanded to Asian countries in 1970.Two field studies were conducted with widely planted rice(Oryza sativa L.)cultivars at Eagle Lake,Texas,USA to determine the effects of nitrogen(N)management in main(first)crop(MC)and ratoon(second)crop(RC)on RC yield.In 2012 and 2013,one cultivar(Presidio)was adopted to determine the effects of RC N management on ratoon yield and head rice yield.In 2016 and 2017,CL153,CL163 and CL272 in addition to Presidio were adopted to examine the effect of MC N management on ratoon yield and head rice yield.N applied at preflood after MC harvest considerably improved RC yield.Application of 99 kg N ha^(–1)at preflood after MC harvest was practically adequate for RC regrowth,development and approaching the yield potential for Presidio.RC could produce quite high average grain yields of 5.90 to 6.53 t ha–1 in 2012 and 2013,respectively.Main crop N rate only significantly affected MC yield;however,given N applied of 99 kg ha^(–1)at preflood after MC harvest,ratoon yield was not significantly affected by MC N rate.Neither the main nor ratoon crop N management had a significant effect on RC head rice yield.Considerable RC head rice yields(55–65%)were observed in all of the four cultivars and 4 years except for CL272 in 2016.These results indicat that without very high N fertilizer application,rice ratoon crop could produce a considerable grain yield and an expectative head rice yield.Rice ratooning could be a practical way to increase rice yields with the minimal input in south Texas and regions with a similar climate.

Grain yield and nitrogen use efficiency of an ultrashort-duration variety grown under different nitrogen and seeding rates in direct-seeded and double-season rice in Central China

Nitrogen(N) and seeding rates are important factors affecting grain yield and N use efficiency(NUE) in directseeded rice. However, these factors have not been adequately investigated on direct-seeded and double-season rice(DDR) in Central China. The objective of this study was to evaluate the effects of various N and seeding rates on the grain yield and NUE of an ultrashort-duration variety grown under DDR. Field experiments were conducted in 2018 in Wuxue County and 2019 in Qichun County, Hubei Province, China with four N rates and three seeding rates.The results showed that the grain yield of the ultrashort-duration variety ranged from 6.32 to 8.23 t ha–1with a total growth duration of 85 to 97 days across all treatments with N application. Grain yield was increased significantly by N application in most cases, but seeding rate had an inconsistent effect on grain yield. Furthermore, the response of grain yield to the N rates was much higher than the response to seeding rates. The moderate N rates of 100–150 and 70–120 kg N ha–1in the early and late seasons, respectively, could fully express the yield potential of the ultrashort-duration variety grown under DDR. Remarkably higher N responses and agronomic NUE levels were achieved in the early-season rice compared with the late-season rice due to the difference in indigenous soil N supply capacity(INS) between the two seasons. Seasonal differences in INS and N response should be considered when crop management practices are optimized for achieving high grain yield and NUE in ultrashort-duration variety grown under DDR.

Border effects of the main and ratoon crops in the rice ratooning system

The border effect(BE)is widely observed in crop field experiments,and it has been extensively studied in many crops.However,only limited attention has been paid to the BE of ratoon rice.We conducted field experiments on ratoon rice in Qichun County,Hubei Province,Central China in 2018 and 2019 to compare the BE in the main and ratoon crops,and to quantify the contribution of BE in the main crop to that in the ratoon crop.The BE of two hybrid varieties was measured for the outermost,second outermost,and third outermost rows in each plot of both crops.To determine the contribution of BE between the two crops,portions of hills in the outermost and second outermost rows were uprooted during the harvest of the main crop so that the second and third outermost rows then became the outermost rows in the ratoon crop.Overall,the BE on grain yield was greater in the main crop than in the ratoon crop.In the main crop,the BE on grain yield was 98.3%in the outermost row,which was explained by the BE on panicles m^(–2),spikelets/panicle,spikelets m^(–2),and total dry weight.In the ratoon crop,the BE on grain yield was reduced to 60.9 and 27.6%with and without the contribution of the BE in the main crop,respectively.Consequently,55.1%of the BE on grain yield in the ratoon crop was contributed from the main crop.High stubble dry weight and non-structural carbohydrate(NSC)accumulation at the harvest of the main crop were responsible for the contribution of BE in the main crop to that in the ratoon crop.Our results suggest that increases in stubble dry weight and NSC accumulation at the harvest of the main crop could be important strategies for developing high-yielding cropping practices in the rice ratooning system.

Impacts of the north migration of China＇s rice production on its ecosystem service value during the last three decades (1980-2014)

The ecosystem services value （ESV） of rice system has received increasing attention in agricultural policy decision. Over the last three decades, China＇s rice production presented an obviously trend that moving towards north locations. However, the impacts of this migration on the ESV of rice production have not been well documented. In this paper, we analyzed the change of the ESV of rice production in China under ＂north migration＂ and ＂no migration＂ scenarios during 1980-2014 based on long-term historical data. The results showed that both the positive and negative ESVs of rice production were lower under ＂north migration＂ than under ＂no migration＂ scenarios. The total ESV during 1980-2014 was reduced by 15.8%. ＂North migration＂ significantly reduced the area-scaled ESV since the early 1990s; while its impact on yield-scaled ESV was not significant. The effects of＂north migration＂ on ESV showed great spatial variation. The greatest reduction in total and area-scaled ESV was observed in south locations. While the yield-scaled ESVs of most south locations were enhanced under ＂north migration＂ scenario. These results indicated that ＂north migration＂ has generated adverse effects on the ESV of rice production. An adjustment in the spatial distribution is essential to protecting the non-production benefits of rice ecosystem.

Infection Behaviour of Melampsora larici-populina on the Leaf Surface of Populus purdomii

Behaviours of urediospore germtube in Melampsora larici-populina on the leaf surface of Populus purdomii were studied by light microscope, scanning electron microscope （SEM）, transmission electron microscope （TEM）, and fluorescence microscope. Crab-like fusion cells on leaf surface, intercellular hyphal cells in leaf tissues, as well as nucleus states, were observed and counted up in this study. Under unsaturated humidity, 32% of germinated tubes fused into a distinguishable swollen crab-shaped cell at the merging site, and 10.5% of observed crab-like cells had more than three nuclei. Wedge-shaped mycelia developed and then penetrated the leaf surface directly, or indirectly through stomata. Tips of germtube passed through the intercellular cells of poplar leaves directly were found in TEM. Aniline blue dyeing also showed that the infecting hyphae could invade into the cuticle and epidemic cell wall directly. For the case of infection through stomata, there were two different situations. Short branches and wedge hyphae usually penetrated the leaf surface via opened stomata, whereas, some germtube branches and wedge hyphae penetrated leaves through the guard cell walls or stoma lips. In the latter case, the stomata were always closed. The samples from wild forestlands had the same fused cells and wedge hyphae, but the occurrence rate was much higher than that in the chamber. Even under the saturated air humidity, germtubes could roll back and formed fusion structure, or merged together with their tips. The fusion cells might centralize the plasma of merged germtubes and have a strong survival capacity to protect germtubes from dying under arid circumstances, and provide a chance of genetic variation as well.

Differential Responses of Water Uptake Pathways and Expression of Two Aquaporin Genes to Water-Deficit in Rice Seedlings of Two Genotypes

Water-deficit （WD） is a major abiotic stress constraining crop productivity worldwide. Zhenshan 97 is a drought-susceptible rice genotype, while IRAT109 is a drought-resistant one. However, the physiological basis of the difference remains unclear. These two genotypes had similar total water uptake rates under both WD and well-watered （WW） conditions, and their water uptake rates under WD were significantly decreased compared with those under WW. However, the water uptake rate via the cell-to-cell pathway was significantly increased in Zhenshan 97 but decreased in IRAT109 under WD, whereas the opposite trends were observed through the apoplastic pathway. These results indicated that the stress responses and relative contributions of these two water uptake pathways were associated with rice genotype under WD. The expression levels of OsPIP2;4 and OsPIP2;5 genes were significantly higher in roots of Zhenshan 97 than in IRAT109 under the two conditions. OsPIP2;4 expression in roots was significantly up-regulated under WD, while OsPIP2;5 expression showed no significant change. These results suggest that the expression levels of OsPIP2;4 and OsPIP2;5 in rice are dependent on genotype and water availability. Compared with Zhenshan 97, IRAT109 had a higher root dry weight, water uptake rate and xylem sap flow rate, and lower leaf water potential and root porosity under WD, which might be responsible for the drought resistance in IRAT109.