Evaluation of green manure technology in tropical lowland rice systems

Green manure (GM) is not superior to organic fertilizer in terms of agronomic efficiency. Use of GM destabilizes rice yield, and has higher unit production cost than N fertilizers. It produces higher cereal yields in farmers' field, but gives negative or trivial returns in the short-term conditions. When compared with grain legumes (GL) grown under similar conditions, GM is not economical both in the short- and long-term conditions. Integrating GL in the existing cropping system without disturbing the main crops in the system appears to have a greater chance of adoption, and may also provide long-term economic benefits to low-land rice-based systems. The economic feasibility of GM can be improved by enhancing its use as food and feed, which will improve its short-term advantage. The lesson for developing technologies in future is that they should have economic benefits in the short-term, otherwise these will be rejected by farmers, despite their long-term advantages.     

组合用药防治超级杂交稻甬优12病虫害及效益分析

于2014年在杭州市余杭区良渚街道纤石村水稻绿色防控区,进行了不同药剂组合、不同施药时期全程防控超级杂交稻甬优12病虫害的试验,同时考察了成本效益。结果显示,组合用药在减少化学农药施用量和节约成本的同时能有效防控多种病虫害。在栽培与肥水管理措施相同的情况下,与处理3(农民常规防治方法)相比,处理1减少用药次数1次,节约成本418.5元/hm~2,挽回稻谷损失1 264.5 kg/hm~2(增产12.25%),增收14.30%;与处理3相比,处理2用药次数减少1次,挽回稻谷产量损失603.0 kg/hm~2(增产5.84%),增收5.90%。表明不同药剂组合在防治水稻病虫害的成本效益方面存在较大差异,选择合适的用药方案可以起到节本增效、保护生态环境和提高稻米品质的作用。     

Plant characteristics associated with weed competitiveness of rice under upland and lowland conditions in West Africa

Weeds are a major constraint to rice (Oryza spp.) production in West Africa. Superior weed competitive rice genotypes may reduce weed pressure and improve rice productivity. Two upland and two lowland experiments were conducted in southern Benin to examine genotypic variations in weed-suppressive ability and grain yield under weedy conditions, and to identify plant characteristics that could be used as selection criteria for improved weed competitiveness. A total of 19 genotypes, including Oryza sativa and Oryza glaberrima genotypes and interspecific hybrids developed from crossing O. sativa and O. glaberrima, were grown under weed-free and weedy conditions in an upland with supplemental irrigation and in a flooded lowland. In weedy plots, hand weeding was done once or not at all. Mean relative yield loss across all genotypes due to weed competition ranged from almost 0% to 61%. Large genotypic variations in weed biomass and grain yield under weedy conditions were found. Visual growth vigor at 42 and 63 days after sowing (DAS) under weed-free conditions significantly correlated with weed biomass at maturity in both upland and lowland experiments (R² = 0.26–0.48). Where weed pressure was low to moderate, with mean relative yield loss less than 23%, the multiple regression models using grain yield and plant height at maturity or only grain yield measured under weed-free conditions as independent variables could explain 66–88% of the genotypic variation in grain yield under weedy conditions. At higher weed pressure (mean relative yield loss: 61%), as observed in one of the upland experiments, biomass accumulation of rice at 42 days after sowing was associated with higher grain yield under weedy conditions. Biomass accumulation also significantly correlated with visual growth vigor at the same sampling dates. Therefore, we conclude that grain yield, plant height at maturity and visual growth vigor at 42–63 DAS under weed-free conditions appear to be useful selection criteria for developing superior weed competitive rice genotypes.     

Influence of transgenic hybrid rice expressing a fused gene derived from cry1Ab and cry1Ac on primary insect pests and rice yield

Although dozens of transgenic Bacillus thuringiensis (Bt) rice lines have been developed, none of them has been released to farmers. Under field conditions, we evaluated the influence of a hybrid Bt rice on the primary rice insect pests and rice yield in 2005 and 2006. Four treatments were evaluated, including Bt and non-Bt rice treated with insecticides when necessary, and unprotected Bt and non-Bt rice. Unprotected Bt rice exhibited stable and high control of the three primary lepidopteran pests, Chilo suppressalis Walker, Tryporyza incertulas Walker and Cnaphalocrocis edinalis Güenée. Under unprotected conditions, larval densities of these three pests in Bt plots decreased by 87.5–100% compared to those in non-Bt plots, and percentages of damaged stems and leaves remained less than 0.6% during the entire rice growing season. In early rice growth stages, populations of two important planthoppers, Nilaparvata lugens Stål and Sogatella furcifera Hovarth, were significantly affected only by protection level (protected vs unprotected). However, in late rice growth stages (filling and maturing), densities of planthoppers were significantly affected both by protection level and by rice type (Bt vs non-Bt), and densities of N. lugens were significantly higher in Bt plots than in non-Bt plots under unprotected conditions. Pesticide sprays were reduced by 60 and 50% in protected Bt vs protected non-Bt plots in 2005 and 2006, respectively. Yield of unprotected Bt rice increased by 60–65% compared to unprotected non-Bt rice, but decreased by 28–36% compared to protected Bt rice. These results show that Bt rice increased yield greatly, but still required pesticide sprays to avoid losses caused by non-target insect pests.     

Effect of non-lethal low phytic acid mutations on grain yield and seed viability in rice

Low phytic acid (LPA) crops have recently been considered as a potential way to combat nutritional and environmental issues related to seed phytic acid phosphorus (PA-P). Although, a number of LPA mutant lines have been developed in various crops, they are often featured with lower grain yield and seed viability compared with wild type (WT) parents. We recently developed several LPA mutant lines in rice with PA-P reductions varying from 33.8% to 63.6%. In this study, the performance of grain yield and seed viability of these mutants were investigated. Four of the five mutant lines had 12.5–25.6% reductions in grain yield compared to the corresponding WT parental lines. The reduction in grain weight, varying from 5.4% to 10.7%, was found to be the main causative factor of yield reduction. Similarly, LPA mutants had inferior seed viability to their corresponding WT parent varieties; all mutant lines had a significantly lower simplified vigour index (seed germination rate × seedling dry weight) than their parents, with reductions of 7.8–26.3%, although some mutant lines had similar germination rates as their WT parents. The two mutant lines, which had similar germination rates as their WT parent, however, had significantly lower field emergence rates. More pronounced differences of simplified vigour index were observed after artificial aging treatments between four LPA lines from their WT parents, implying that LPA rice seeds were more susceptible to storage than WT. The yield and yield-related traits of F₂ plants and F₃ lines from three crosses were evaluated; the results showed that while LPA was associated with significantly lower grain yield and grain weight than WT sibs, there were also LPA plants and lines that out-performed WT controls. These results implied that the negative effect of LPA mutations on grain yield might be reduced or minimized through cross and selection breeding. The implications of these findings were discussed with regard to LPA rice breeding and potential commercial production.     

我国水稻重要农艺性状分子遗传研究进展及在育种上的应用

水稻是我国的主要粮食作物,在人口快速增长和自然环境不断恶化的今天,传统的育种技术已经很难满足当前水稻育种的需求,分子育种技术逐渐成为育种工作者解决当前困境的主要方法。经过几十年的努力,中国科学家不仅在水稻遗传学和功能基因组学领域取得了令世界瞩目的成就,还在水稻分子育种方面为提高粮食产量、营养质量和环境效益方面做出了巨大努力。本文主要综述了我国科学家在水稻分子遗传和分子育种方面取得的成就并进行讨论。     

两个杂交稻组合及其亲本材料对白背飞虱抗性的研究

采用田间白背飞虱种群调查和水稻产量、室内白背飞虱蜜露量、产卵量及卵发育率测定,在浙江富阳和重庆秀山两地研究了杂交稻组合及其亲本材料对白背飞虱的抗虫性.田间试验结果表明不育系协青早A和珍汕97A表现出对白背飞虱比感虫对照品种TN1更感虫的"超感虫性",稻株上的若虫量分别高达371.1和292.5只/丛.在杂交稻汕优63和协优9308上的若虫数量与TN1上的相当,杂交稻的感虫性主要来源于其不育系亲本.在无杀虫剂防治的情况下,感虫杂交稻组合的千粒重和产量损失率高达22%和78%左右,不育系材料被完全毁灭,表现为虫量越大,千粒重下降幅度越大,产量损失率越高.蜜露量测定表明,恢复系明恢63和9803具有一定的耐虫性.白背飞虱在杂交稻及其亲本上的产卵量和卵发育率没有显著差异.还对杂交稻抗虫性的改良进行了讨论.     

转基因抗虫性水稻恢复系选育及特性分析

将优质抗稻瘟病水稻恢复系成恢177与转基因水稻Bt明恢63杂交并回交1次,采用PCR分析、试纸条检测、室内和田间人工接虫鉴定抗虫性,并结合系谱法选择农艺性状,病圃接种鉴定稻瘟病抗性,育成具转基因抗虫性的水稻新恢复系Bt5198。采用离体茎秆法接种二化螟卵块,新恢复系Bt5198和Bt明恢63的幼虫死亡率均为100%。在田间人工接虫条件下,该恢复系对二化螟和三化螟均表现高抗,与4个不育系配制的杂种F1仍保持良好的抗虫性,且杂种优势明显。两年稻瘟病抗性鉴定结果表明,新恢复系Bt5198的叶瘟和颈瘟抗性水平与成恢177相当,明显优于Bt明恢63。Bt5198的种子发芽率和花粉量与成恢177相当,Bt基因导入水稻恢复系不会对种子生活力和制种产量造成显著影响。在无选择标记基因的转基因后代中,结合利用试纸条检测和室内、田间人工接虫鉴定是筛选Bt基因抗虫性的有效方法。     

超级稻楚粳37号肥料减量增效试验研究

以超级稻楚粳37号为试验材料,研究了不同肥料减量处理对水稻产量的影响。结果表明,在楚粳37号高产栽培过程中,适当降低化肥使用量(减量30%),不仅能确保高产,而且节本增效。     

Quality characteristics and field performance of selectable marker-free transgenic rice with antisense Wx gene and improved quality derived from the elite parents of hybrid indica rice

In rice grains, high amylose content (AC) is correlated with poor grain quality, particularly in indica hybrid rice. To obtain indica hybrid rice with improved cooking and eating qualities, we introduced the antisense Waxy (Wx) gene into 2 elite parental lines of indica hybrid rice by using co-transformation methods. Subsequently, we selected several elite homozygous transgenic lines that did not contain the selectable marker. The expression of the endogenous Wx gene of the selected transgenic lines was significantly downregulated, resulting in low AC in the mature seeds; moreover, the AC in some lines reduced to the level observed in glutinous rice. With the decrease in AC, the gel consistency of the transgenic rice became softer, and the gelatinization temperature tended to be higher than those of the wild types, especially in the case of the Longtefu-derived transformants. We also analyzed the pasting properties of the selected transgenic low-AC lines, and we noted an improvement in the pasting properties of the transgenic rice lines. The results from a field trial indicated that the grain weights of the transgenic lines with lower AC exhibit remarkable reduction compared with those of the wild types.     

中国杂交稻的"超感虫性"研究概况

介绍了高度感虫的中国杂交稻推广带来水稻害虫生态地位发生的变化.褐飞虱和白背飞虱上升为杂交稻上最突出的极易爆发成灾的重要害虫.20世纪70年代以前,白背飞虱只是水稻上的次要害虫,但80年代以来其种群大大增加.由于它从中国南部杂交稻种植区大范围迁飞,白背飞虱也成为中国中部地区粳稻上的重要害虫.由于种植具有抗褐飞虱基因Bph1的杂交稻组合,褐飞虱种群曾得到暂时的控制.然而,抗虫性的杂交稻在中国中部和南部稻飞虱迁飞区推广以后,褐飞虱生物型发生了改变,对抗虫品种产生了适应性.1990年以后,以前表现抗虫的杂交稻变得高感褐飞虱.缺乏抗虫性主基因不是中国杂交稻对稻飞虱超感性的充分理由,杂交稻旺盛生长的杂种优势可能是稻飞虱生殖力提高的部分原因.中国杂交稻对稻飞虱的超感虫性是从不育系遗传而来的.因此,杂交稻抗虫性的提高有赖于不育系的改良.利用持久抗性和多抗性的IR品种如IR64作为恢复系是改善中国杂交稻的超感虫性的一种有效方法.杂交稻上二化螟和三化螟为害也有所增加.与常规稻相比,杂交稻是一种更有利的食料植物且耐虫性更强.进行水稻产量损失的估计,尤其是水稻本身对螟虫为害的补偿能力,以及螟虫和杂交稻之间的生态学关系的研究有助于评价杂交稻对螟虫田间抗性的实际影响.     

Physiological characterization of introgression lines derived from an indica rice cultivar, IR64, adapted to drought and water-saving irrigation

Water scarcity threatens sustainable rice production in many irrigated areas around the world. To cope with the scarcity, aerobic rice culture has been proposed as a promising water-saving technology. The objective was to elucidate the physiological attributes behind the performance of rice introgression lines in water-saving culture. We evaluated yield potential and physiological adaptation traits to water deficit of BC₃-derived lines with the genetic background of an elite indica cultivar, IR64, in the field and in pot experiments. One line, YTH183, had 26% higher yield than IR64 under non-stress conditions (895 vs. 712 g m⁻² on average). This was attributed to enlarged sink capacity due to large grain size, which contributed to more efficient use of assimilates and hence a higher harvest index. YTH183 also showed better dehydration avoidance under intermittent soil drying, due to the adaptive response of deep rooting to water deficiency. The grain yield of YTH183 exceeded that of IR64 by 92-102% under moderate water deficit caused by limited irrigation in aerobic rice culture (143 vs. 72 g m⁻²). Two introgressed segments on chromosomes 5 and 6 might, at least in part, confer the higher yield potential and greater dehydration avoidance in YTH183 simultaneously. Advanced backcross breeding combined with molecular genetics and physiological characterization of introgressed segments would be effective for developing new rice cultivars with high yield potential and drought adaptation traits.     

Current use of transgenic herbicide-resistant soybean and corn in the USA

The objective of this paper is to outline the current use of herbicide-resistant soybean and corn in the United States and describe the ramifications of utilizing these crops derived from biotechnology. The popular press and news articles detail the positions of consumers, environmental advocates, and the agriculture industry. Recent concerns expressed by consumers throughout the world have affected how herbicide-resistant crops are viewed and thus potentially the adoption of the technology. The paper will focus on the benefits and risks of using herbicide-resistant soybean and corn, specifically constructs that confer resistance to glyphosate. Glufosinate-resistant crops will also be discussed.     

Breeding and Characterization of a New Rice Restorer Line Containing Bt Gene

Bt5198, a new rice restorer line containing Bt gene, was developed from the cross and backcross of the elite restorer line Chenghui 177 with Bt Minghui 63, a transgenic Bt restorer line. The inbred lines were evaluated using PCR amplification, test paper evaluation, insect resistance evaluation in both the laboratory and paddy fields, nursery evaluation of rice blast resistance and pedigree selection of agronomic traits. Larval mortalities on Bt5198 and Bt Minghui 63 were 100% when rice culms were inoculated with the eggs of the striped stem borer (SSB) in the laboratory. Bt5198 was highly resistant against SSB and the yellow stem borer (YSB) under field conditions. The F₁ hybrids derived from Bt5198 and four cytoplasmic male sterile (CMS) lines were also highly resistant to SSB and YSB and had a significant heterosis. Two-year evaluation of rice blast resistance confirmed that the resistance levels of Bt5198 to leaf blast and neck blast were similar to those of Chenghui 177 and significantly better than those of Bt Minghui 63. Seed germination ability and pollen yield of Bt5198 were similar with Chenghui 177, suggesting that the introduction of the Bt gene into the new restorer line had no significant effects on seed vitality or the yield of seed production. To identify the presence of the Bt gene, it was effective to combine test paper examination with the evaluation of insect-resistance, both in the laboratory and under field conditions.     

稻蟹生态种养模式水稻栽植方式筛选研究

本研究在投放相同数量河蟹的基础上设置了“6比空”“12比空”和“18比空”3种水稻栽植方式,通过综合分析水稻产量、稻米品质和河蟹产量等数据,明确适宜稻蟹生态种养模式下机械化操作的最优水稻栽植方式。结果表明,与普通稻蟹种养模式下的水稻产量相比,比空栽植方式通过边行效应增加了单位面积有效穗数,补充了一部分由于空行引起的水稻产量缺失,同时降低了稻米蛋白质含量,提高了整精米率和河蟹的回捕率。综合水稻和河蟹收入,以“12比空”栽植模式的产投比最高,达到2.83,比水稻单一种植模式增收13 575元/hm2,比普通稻蟹种养模式增收3 120元/hm2,是稻蟹生态种养经济效益较优的水稻栽植方式之一。     

双价抗虫转基因大豆抗苜蓿夜蛾分析

苜蓿夜蛾是影响我国大豆生产的重要食叶性害虫之一.在实验室和网室人工接虫条件下,对已获得的遗传稳定的双价抗虫转基因大豆抗苜蓿夜蛾能力进行了分析.结果表明,与对照非转基因大豆相比,抗虫转基因大豆株系T5-150和T5-195的叶片损害程度明显减轻;同时,苜蓿夜蛾幼虫食叶量显著下降、存活天数缩短,发育变慢,蛹化数也显著降低.表明抗虫转基因大豆抗苜蓿夜蛾能力显著提高.     

稻米品质调控的分子基础及非生物胁迫对稻米品质的影响

水稻是世界上最重要的粮食作物之一，为全球超过半数人口提供食物来源。近些年来，随着温饱问题的解决，稻米品质日益受到关注。随着现代生物技术和生物信息技术的发展，控制稻米品质的基因相继被克隆并应用于水稻育种。本文综述了稻米品质调控分子机制，并对干旱、低温、高温、盐胁迫对稻米品质的影响进行了概述，以期为改善非生物胁迫下的稻米品质提供参考。     

冬季轮茬作物养分还田特征及其对水稻产量和稻田水环境的影响

采用大田小区试验研究了不同冬季轮茬种植模式下作物养分还田特征,及其对水稻产量和稻田表水环境主要参数的影响,并对各轮茬种植模式下的经济效益进行了分析。结果表明,不同冬季轮茬作物产量差异较大,且其养分含量差异亦较大,导致各轮茬种植模式下养分还田量差异显著。“红花草-水稻”模式下,N、P素还田量均最高。从短期效应来看,冬季作物轮茬对后茬水稻株高、产量及肥料利用率的影响均不显著。然而,从环境效应角度考量,不管何种轮茬种植模式,均应充分考虑水稻季基肥到分蘖肥期间的稻田水环境效应,监测发现,稻田表水总磷（TP）、可溶性总磷（DP）平均含量几乎都超过了易引发水体富营养化的临界水平（溶解磷0.05 mg/L和总磷0.1 mg/L）。同时,从周年经济效益角度考量,“青饲小麦-水稻”和“蚕豆-水稻”种植模式具有较高收益,可进一步推广应用。     

应用DNA标记分析稻飞虱的抗性基因

简要地回顾了水稻抗飞虱的遗传位点定位和作图的新进展.来自具有不同基因组的野生稻渗入系的4个抗褐飞虱基因Bph 1、 bph 2、 bph 4和Bph 9,以及4个暂定名抗褐飞虱基因Bph 10(t)、bph 11(t)、bph 12(t)和Bph 13(t),目前已被定位于水稻12条染色体中的5条.其中,Bph 1、 bph 2、 Bph 9和Bph 10(t)在水稻第12染色体的长臂上形成1个连锁区段,位于bph 2位点附近约25 cM.检测出几个对田间抗性和杀卵作用有影响的QTL.抗白背飞虱基因Wbph 1、 Wbph 2和Wbph 6(t)已经或暂时定位了.粳稻中对白背飞虱具有杀卵抗性的QTL已进行了详细的分析,在第6染色体的短臂上检测到有效的QTL,在同一位点鉴定出1个显性的杀卵基因Ovc.在杀卵基因Ovc存在时,第1染色体上的1个QTL和第5染色体上的2个QTL增加白背飞虱的卵死亡率.用DNA标记进行QTL作图可以加深人们对作物抗虫性中复杂的生理和遗传机理的理解.标记辅助选择可以加速培育具多基因抗虫性的作物,还可以将野生种中的有利抗虫特性转入改良品种中,增加作物抗虫性的持久性和遗传多样性.     

Genetic analysis and validation of quantitative trait loci associated with reproductive-growth traits and grain yield under drought stress in a doubled haploid line population of rice (Oryza sativa L.)

Drought is a major constraint for rice production and yield stability in rainfed ecosystems, especially when it occurs during the reproductive stage. Combined genetic and physiological analysis of reproductive-growth traits and their effects on yield and yield components under drought stress is important for dissecting the biological bases of drought resistance and for rice yield improvement in water-limited environments. A subset of a doubled haploid (DH) line population of CT9993-5-10-1-M/IR62266-42-6-2 was evaluated for variation in plant water status, phenology, reproductive-growth traits, yield and yield components under reproductive-stage drought stress and irrigated (non-stress) conditions in the field. Since this DH line population was previously used in extensive quantitative trait loci (QTLs) mapping of various drought resistance component traits, we aimed at identifying QTLs for specific reproductive-growth and yield traits and also to validate the consensus QTLs identified earlier in these DH lines using meta-analysis. DH lines showed significant variation for plant water status, reproductive-growth traits, yield and yield components under drought stress. Total dry matter, number of panicles per plant, harvest index, panicle harvest index, panicle fertility, pollen fertility, spikelet fertility and hundred grain weight had significant positive correlations with grain yield under drought stress. A total of 46 QTLs were identified for the various traits under stress and non-stress conditions with phenotypic effect ranging from 9.5 to 35.6% in this study. QTLs for panicle exsertion, peduncle length and pollen fertility, identified for the first time in this study, could be useful in marker-assisted breeding (MAB) for drought resistance in rice. A total of 97 QTLs linked to plant growth, phenology, reproductive-growth traits, yield and its components under non-stress and drought stress, identified in this study as well as from earlier published information, were subjected to meta-analysis. Meta-analysis identified 23 MQTLs linked to plant phenology and production traits under stress conditions. Among them, four MQTLs viz., 1.3 for plant height, 3.1 for days to flowering, 8.1 for days to flowering or delay in flowering and 9.1 for days to flowering are true QTLs. Consensus QTLs for reproductive-growth traits and grain yield under drought stress have been identified on chromosomes 1 and 9 using meta-QTL analysis in these DH lines. These MQTLs associated with reproductive-growth, grain yield and its component traits under drought stress could be useful targets for drought resistance improvement in rice through MAB and/or map-based positional analysis of candidate genes.