季节性干旱对水稻生长发育的影响及其生物防控策略

四川水稻生产季节性干旱问题突出。本文综述了季节性干旱对水稻生理、生长发育、产量及其构成因素和品质的影响,以及在气孔调节、渗透调节、激素调节、抗氧化酶保护、逆境蛋白保护等生理调控方面的研究进展,介绍了水稻抗旱性的遗传研究和常规抗旱育种、抗旱生理育种、抗旱分子育种以及耐旱节水水稻品种筛选的研究现状。     

水稻抗旱研究进展

干旱胁迫是影响水稻生长发育的重要环境因素之一。水稻在干旱胁迫条件下,产生相应的生理变化并诱导特定相关基因的表达,这些生理生化变化与相关基因的表达减少了水稻在干旱胁迫条件下带来的伤害。在此,简要概述了干旱对水稻的影响、水稻的抗旱生理生化机制、水稻抗旱相关基因研究及抗旱育种方面的一些研究现状,为提高水稻抗旱性和抗旱育种提供相关参考。     

野生大豆种质资源抗旱性评价

在年降雨量不足40mm的敦煌市,设干旱胁迫和正常灌水两个处理进行试验研究,考察与抗旱性相关的产量性状,采用抗旱指数的方法,从生态抗旱的角度进行抗旱性鉴定,探索野生大豆的抗旱潜力,拓宽大豆抗旱育种基因资源。应用产量性状指标评定野生大豆品种的抗旱性,简单、易行、可靠性高,尤其在进行野生大豆品种资源抗旱鉴定筛选过程中更显示出它的优越性。     

耐旱水稻种质资源的筛选初探

通过分析干旱胁迫灌水与浅水灌溉对照处理条件下水稻生育期、农艺性状及产量性状的变化,探讨了20份水稻种质资源的耐旱性。结果表明:干旱胁迫处理条件下水稻生育期延长,农艺性状及产量因子水平均低于对照处理条件下水平。从抗旱指数与理论产量综合评价,垦01-1387、垦稻12、绥粳3、松粳4、北稻4等品种(系)的抗旱能力相对较强。     

马铃薯资源抗旱性鉴定和筛选

干旱是马铃薯生产的重要限制因子之一.本研究利用42个马铃薯材料(品种),采用正常浇水和干旱胁迫两种理,对供试材料进行了抗旱能力评价.结果表明:虎头和高原7号等四倍体品种以及CE 66和HS 66等二倍体材料抗旱能力较强,其中高原7号和虎头等品种在干旱胁迫下表现出了较高产量,适宜应用于抗旱育种.干旱胁迫下,植株株高普遍降...     

抗旱性不同的春小麦品种籽粒萌发期α-淀粉酶活性及其同工酶分析

为了解春小麦萌发期生理生化变化对干旱胁迫的响应及为早期抗旱筛选鉴定提供科学依据,选用抗旱性不同的9个春小麦品种为材料,在20%聚乙二醇(PEG6000)干旱胁迫下和非干旱胁迫下进行萌发试验,研究了α-淀粉酶活性及其同工酶的表达.结果表明:1)在两种胁迫处理下,α-淀粉酶活性在品种间都存在着差异,但干旱胁迫下抗旱品种α-淀粉酶活性显著高于干旱敏感品种;2)α-淀粉酶活性与胚芽鞘长度之间呈显著正相关;3)在20%PEG6000胁迫下,抗旱品种α-淀粉酶同工酶受抑制较小,条带较多,胚芽鞘长度与主胚根长度受抑制较小.因此认为,抗旱品种在干旱胁迫下有着较高的萌发势,可能与具有表达α-淀粉酶同工酶的强势基因型有关;干旱胁迫下α-淀粉酶活性和r淀粉酶同工酶可以作为春小麦抗旱性筛选和鉴定的指标.     

基于EMS诱变的济麦22抗旱节水突变体创制与鉴定

干旱和水资源匮乏是北方麦区小麦生产中存在的主要问题之一,培育抗旱型和节水型小麦新品种是解决这一问题的有效途径,创制抗旱节水新种质是培育小麦品种的重要物质基础。本研究用甲基磺酸乙酯(EMS)诱变小麦品种济麦22,获得济麦22遗传稳定突变体223份,采用旱地增产和聚乙二醇(PEG-6000)模拟干旱胁迫方法,筛选出18份抗旱增产突变体;经旱作胁迫和节水性鉴定,12份突变体具有极强抗旱性(抗旱指数DI≥1.300)、10份突变体具有极强节水性(节水指数WSI≥1.400),其中7份突变体同时具有极强抗旱性和极强节水性,编号分别为22-3、22-4、22-5、22-9、22-13、22-16和22-17,可以作为抗旱型和节水型优异种质加以利用;此外,突变体22-1、22-10、22-11、22-12和22-14可以作为抗旱种质,22-2、22-7和22-18可以作为节水种质。经相关性分析,突变体在雨养生境下的产量相关性状可作为小麦抗旱种质的筛选指标,突变体穗粒数以及在节水生境下的单位产量可作为小麦节水种质筛选指标。     

中国水稻抗旱研究进展

对水稻在干旱胁迫下的伤害机理和抗旱机制以及干旱对水稻不同生育时期生理性状的影响方面进行了总结和综述,以水稻的需水特征为依据,提出抗旱育种和节水栽培等抗旱减灾措施.     

油菜和甘芥杂交后代薹花期耐旱性鉴定

为筛选远缘杂交后代中的抗旱材料,连续4年于生殖生长关键时期（薹花期）,设正常灌水及干旱胁迫处理,考察包括甘蓝型油菜、芥菜型油菜及甘芥杂交后代共计43份材料成熟期产量及12个产量相关性状,采用经典抗旱指数法结合连锁聚类分析,筛选优异抗旱资源,并分析干旱对产量相关因子,尤其是产量组成因子的影响,筛选关键的抗旱性鉴定指标。结果表明,3个产量构成因子中,角果数对薹花期干旱最敏感,千粒重及每角粒数变化不大,干旱使得一次分枝数、侧枝角果数显著减少,导致总角果数下降,成为影响产量下降的主要原因,相关分析表明,干旱条件下相对总角果数、相对侧枝角果数、相对株高与抗旱指数呈显著正相关,相对侧枝角果数、相对总角果数可作为油菜薹花期抗旱性筛选指标,相对一次分枝数、相对株高也可作为初筛指标;同一材料在不同程度干旱胁迫下,其抗旱性表现有差别,4年共筛选出17份抗旱材料,抗旱性比较稳定的有3份,其中1份甘芥杂交后代材料抗旱性稳定且干旱条件下产量较高。     

中国水稻抗旱研究进展

对水稻在干旱胁迫下的伤害机理和抗旱机制以及干旱对水稻不同生育时期生理性状的影响方面进行了总结和综述，以水稻的需水特征为依据，提出抗旱育种和节水栽培等抗旱减灾措施。     

栽培稻抗旱性研究的现状与策略

 水资源短缺正成为制约我国农业发展的重要因素。培育抗旱的栽培稻品种并实现水稻旱作，不但可在很大程度上节约水资源，而且有利于增产稳产，节约能源和减少环境污染。抗旱性包括逃旱性、避旱性、耐旱性和复原抗旱性。形态生理学的研究揭示出大量的与栽培稻抗旱性有关的形态特征和生理特性，如根系和叶片性状、生育期、渗透调节、脱落酸含量与栽培稻抗旱性密切相关，且已利用分子标记对上述性状进行了基因定位（QTL）研究。旱稻品种改良也已取得重大进展。在进行抗旱品种改良的基础上，通过引进相应的栽培技术，节水种植，实现水稻旱作，并达到稳产与增产的目的，是抗旱性研究的战略目标。在增产、稳产和优质的前提下，以培育耐旱性极强的水稻（或旱稻）为中心，建立有代表性的抗旱性研究基地, 进一步加强稻属抗旱基因资源的发掘和创新、抗旱生理学和遗传学的研究、利用现代生物技术实现不同物种间抗旱基因的转移、建立节水种植栽培技术新体系是目前抗旱性研究的主要内容。     

Breeding for drought tolerance: Direct selection for yield, response to selection and use of drought-tolerant donors in upland and lowland-adapted populations

Drought is the most important constraint reducing rice yield in rainfed areas. Earlier efforts to improve rice yield under drought mainly focused on improving secondary traits because the broad-sense heritability (H) of grain yield under drought stress was assumed to be low, however gains in yield by selecting for secondary traits have not been clearly demonstrated in rice. In present study, the effectiveness of direct selection for grain yield was assessed under lowland reproductive stage stress at Raipur in eastern India and under upland reproductive stage drought stress at IRRI. The selection under severe stress (in both upland and lowland trials) resulted in greater gains under similar stress levels (yield reduction of 65% or greater under stress) in evaluation experiments than did selection under non-stress conditions, with no yield reduction under non-stress conditions. We observed similar H of grain yield under stress and non-stress conditions, indicating direct selection for yield under drought will be effective under both lowland and upland drought stresses. None of the secondary traits (panicle exsertion, harvest index, leaf rolling, leaf drying) included in our study showed a higher estimate for H than grain yield under stress. Secondary traits as well as indirect selection for grain yield under non-stress situation were predicted to be less effective in improving yield under drought in both lowland and upland ecosystem than direct selection for grain yield under the respective stress situations. The low, but positive values observed for genetic correlation (r_G) between yield under stress and non-stress indicated that it is possible to combine drought tolerance with high-yield potential but low values also indicated that selection for grain yield needs to be carried under stress environments. The study also indicated that under lowland drought stress, the use of highly drought-tolerant donors, as parents in crosses to high yielding but susceptible varieties resulted in a much higher frequency of genotypes combining high-yield potential with tolerance than did crosses among elite lines with high-yield potential but poor tolerance. Breeding strategies that use drought-tolerant donors and that combine screening for yield under managed drought stress with screening for yield potential are likely to result in the development of improved cultivars for drought-prone rainfed rice producing areas.     

Combined Drought and Heat Stress in Rice: Responses,Phenotyping and Strategies to Improve Tolerance

Simultaneous occurrence of drought and heat stress will have significant negative impact on rice yield, especially under upland conditions. The projected increase in global temperatures and reduced precipitation will increase the frequency of occurrence and intensity of these stresses, threatening rice production. Despite recognizing the importance of combined stress in rice, the knowledge generated in this area is very limited. Though complex, understanding combined stress tolerance of rice under water saving cultivation is more critical towards development of climate resilient rice cultivars. Here, we summarized the effects of combined stress on rice physiology with more emphasis on reproductive stage. Omics responses, phenotyping and physiology challenges and potential strategies for improving combined stress tolerance in rice are also discussed.     

水稻抗旱性的研究进展

随着全球水资源的日益匮乏和旱灾的日趋严重,水资源短缺正成为制约我国农业发展的重要因素。培育抗旱栽培稻品种并实现水稻旱种,不但可较大程度地节约水资源,且有利于稳产增产、节约能源和减少环境污染,故栽培稻的抗旱性研究作为稻作科学研究的重要课题显得愈来愈重要。本文从水稻抗旱性鉴定形态指标、生理指标和分子标记研究三方面分别概述,并对今后水稻抗旱性方向进行了探讨。     

Water supply from pearl millet by hydraulic lift can mitigate drought stress and improve productivity of rice by the close mixed planting

The authors have proposed the close mixed planting technique using mixed seedlings of two different crop species that results in close tangling of their root systems. Especially, the combination of drought-adaptive upland crops (e.g. pearl millet or sorghum) and flood-adaptive lowland crop of rice would be beneficial to overcome the drought and flood conditions and to reduce the risks of crop failure. In our previous studies, we found that upland crop yield losses by flood stress was mitigated by mix-cropped rice, owing to the oxygen gas released from the rice roots into the aqueous rhizosphere. In the present study, we conducted two experiments to assess whether mixed cropping a drought-resistant cereal, pearl millet, would improve the performance of co-growing drought-susceptible crop, rice under drought conditions. In the field experiment, some grains were obtained from the rice plants mix-cropped with pearl millet under drought condition. However, no rice matured in the single cropping system. In the model experiment using deuterium analysis, it was confirmed that water absorbed by pearl millet roots from deep soil layer was utilized by rice, suggesting that mix-cropped rice could withstand drought stress and complete grain filling using water released into the upper soil layer by hydraulic lift.     

不同粳稻品种耐旱性试验研究

选用9个不同粳稻品种,通过相同断水时间抗旱处理条件下,对品种进行耐旱性试验研究,结果表明:不同品种耐旱性有着很大差异,水稻新品种农大27平均产量最好,极显著高于其他品种;品种间多重比较结果表明,农大27属散穗型,生育繁茂耐旱能力较强,具有大型散穗品种特征。     

Development of drought-resistant cultivars using physiomorphological traits in rice

Drought is a major problem for rice grown under rainfed lowland and upland conditions, but progress in breeding to improve drought resistance has been slow. This paper describes patterns of water-stress development in rice fields, reviews genetic variation in physio-morphological traits for drought resistance in rice, and suggests how knowledge of stress physiology can contribute to plant breeding programmes that aim to increase yield in water-limiting environments. To provide a basis for integrating physiological research with plant-breeding objectives we define drought resistance in terms of relative yield of genotypes. Therefore, a drought-resistant genotype will be one which has a higher grain yield than others when all genotypes are exposed to the same level of water stress.A major reason for the slow progress in breeding for drought resistance in rice is the complexity of the drought environment, which often results in the lack of clear identification of the target environment(s). There is a need to identify the relative importance of the three common drought types; early-season drought which often causes delay in transplanting, mild intermittent stress which can have a severe cumulative effect, and late stress which affects particularly late-maturing genotypes. In addition, in rainfed lowland rice, flooded and non-flooded soil conditions may alternate during the growing season, and affect nutrient availability or cause toxicity.Several drought-resistance mechanisms, and putative traits which contribute to them, have been identified for rice; important among these being drought escape via appropriate phenology, root characteristics, specific dehydration avoidance and tolerance mechanisms, and drought recovery. Some of these mechanisms/traits have been shown to confer drought resistance and others show potential to do so in rice. The most important is the appropriate phenology which matches crop growth and development with the water environment. A deep root system, with high root length density at depth is useful in extracting water thoroughly in upland conditions, but does not appear to offer much scope for improving drought resistance in rainfed lowland rice where the development of a hard pan may prevent deep root penetration. Under water-limiting environments, genotypes which maintain the highest leaf water potential generally grow best, but it is not known if genotypic variation in leaf water potential is solely caused by root factors. Osmotic adjustment is promising, because it can potentially counteract the effects of a rapid decline in leaf water potential and there is large genetic variation for this trait. There is genotypic variation in expression of green leaf retention which appears to be a useful character for prolonged droughts, but it is affected by plant size which complicates its use as a selection criterion for drought resistance.There is a general lack of drought related research for rice in rainfed lowland conditions. This needs to be rectified, particularly considering their importance relative to upland conditions in Asian countries. We suggest that focussing physiological-genetic research efforts onto clearly defined, major target environments should provide a basis for increasing the relevance of stress physiology and the efficiency of breeding programmes for development of drought-resistant genotypes.     

Identification of deletion mutants with improved performance under water-limited environments in rice (Oryza sativa L.)

Rice (Oryza sativa L.) is a semi-aquatic member of the grass family that is poorly adapted to dry environments and has greater sensitivity to water-deficits than other important cereals in this family. To increase productivity in aerobic or water-limited environments rice must overcome its adaptations to flooded environments. Deletion mutants offer an alternative genetic resource for improving drought tolerance. Almost 3500 IR64 deletion mutants were screened under vegetative and reproductive stage drought stress in the field and evaluated for leaf drying and/or grain yield. Seven novel conditional mutants of rice which showed gain of function through continued growth as drought stress developed compared to the wild type were identified. Mutant recovery rate was 0.1%. Further evaluation of putative drought mutants revealed that their average shoot biomass at maturity and grain yield per plant under stress exceeded those of the wild type by two-fold. Studies under controlled conditions confirmed mutants to have continued growth of both roots and shoots as drought developed compared to the wild type, and a tendency for greater water extraction. We propose that deletions in these mutants have affected a regulator of the highly conservative growth response common to irrigated lowland rice cultivars. Our results suggest that screening deletion mutants for performance under managed drought stress in the field could be a highly effective way to identify valuable genetic resources for improved drought response and aerobic adaptation in rice.     

Identification and Characterization of Genes Responsible for Drought Tolerance in Rice Mediated by Pseudomonas fluorescens

Drought is one of the major abiotic stresses which adversely affect crop plants limiting growth and yield potential.Structural and functional characterization of drought stress-induced genes has contributed to a better understanding of how plants respond and adapt to the drought stress.In the present study,differential display technique was employed to study the gene expression of rice plants at the reproductive stage that were subjected to drought stress by withholding water,Pseudomonas fluorescens strain(Pf1) treated plants subjected for drought stress by withholding water and control(well-watered).Differentially expressed c DNAs of six genes(COX1,PKDP,b ZIP1,AP2-EREBP,Hsp20 and COC1) were identified,cloned and sequenced.Real-time q PCR analysis showed that all the six genes were upregulated in drought-stressed plants treated with Pf1.This revealed that the remarkable influence of Pf1 colonization leads to drought tolerance at the reproductive stage.These results showed that high levels of gene expression in plants lacking adequate water can be remarkably influenced by Pf1 colonization,which might be a key element for induced systemic tolerance by microbes.