Selection of Cowpea [(Vigna unguiculata (L.) WALP] Genotypes for Drought Tolerance Using Selection Indices

Cowpea [(Vigna unguiculata (L.)] is one of the most important arid legumes cultivated for pulse and forage production. However, in cowpea, not much is known about the base index selection method in breeding for drought tolerance. Consequently, the present study has been conducted to: 1) evaluate the yield performance of cowpea genotypes under artificial drought and well-watered condition;2) develop a base index using multiple traits for ranking genotype performance. The experiment was a 25 × 2 factorial laid out in a Randomized Complete Block Design (RCBD) with three replications. The experiment was carried out in the screen house at the Department of Horticulture at KNUST. The result showed that KPR1-96-73, Simbo, CZ06-4-16, Wilibaly and Agyenkwa were high yielding in well-water condition while Ghana Shoba, Sangaraka, NKetewade, Ghana-Shoni and Korobalen were high yielding genotypes in water stress condition. The average yield reduction was 60.6% for grain respectively. The biplot displays revealed four groups among the genotypes tested which was based on their yielding capacity and drought tolerance. In cluster B high yielding and drought tolerant genotypes were identified, high yielding and drought susceptible have been identified in cluster A, low yielding and drought tolerant in cluster D, and lastly low yielding and drought susceptible in cluster C. Genotypes in cluster B, were the best due to the fact that it combines high yield and tolerance to drought. They were Ghana Shoni, Nketewade, Sangaraka and Ghana shoba. These genotypes might be suitably employed in further drought tolerance breeding program of cowpea.

Selection of Maize Genotypes with Tolerance to Osmotic Stress Associated with Salinity

Thirteen different inbred lines in relation to the type of grain and life cycles were characterized by testing for osmotic stress associated with salinity. The identification of tolerant genotypes would be an effective strategy to overcome the saline stress. Osmotic stress reduces immediately the expansion of the roots and young leaves which determine a reduction in the size of the plant. A completely randomized design was adopted to test seedlings under controlled conditions of light and temperature. Two treatments were used: 0 mM NaCl (as control) and 100 mM NaCl. After 15 days of complete salinization, the seedlings were harvested and several morphological traits were measured. The morphological traits of growth were leaf growth (Ar1, Ar2, Ar3 and Ar4), dry masses of shoot and root (SDM and RDM, respectively). Also, traits associated with water economy were registered: leaf water loss (LWL) and relative water content (RWC). The morphological traits were expressed in relative terms, while the traits associated with the economy of water were expressed in absolute terms. Uni and multivariate techniques were applied to identify genotypes with divergent behaviors to osmotic stress tolerance. Also, a Tolerance Index was employed to identify superior genotypes. Four clusters were obtained after applying a Cluster Analysis and Principal Component Analysis (PCA). The genotypes were compared to each other with a test of DMS. The results obtained with different statistical techniques converged. Some variables presented a differential weight classification of genotypes. The morphological traits like RDM, SDM, Ar3, Ar4 and Ar5 were the most discriminating. Tolerance Index allowed to classify genotypes, thus SC2 and AD3 lines were that reached highest value of the index and therefore would be tolerant lines, while AF3 and LP3 had a low index and were seen as sensible.

Screening of Rice Accessions for Tolerance to Drought and Salt Stress Using Morphological and Physiological Parameters

Drought and salinity are the most widespread soil problems, posing a big threat to food security in rice growing regions. The present study evaluated the performance of eleven rice genotypes using morphological and physiological parameters, under induced drought and salinity conditions. The seedlings were raised in 5 kg of homogenous soil in plastic bags in the greenhouse. For the drought experiment, each bag was watered with 200 ml of water twice daily until plants reached the five-leaf stage when watering was suspended for 2 weeks for the drought stressed plants but not suspended for the control plants. The experiment was a 2 × 11 factorial and the set up was arranged using the completely randomized design with three replications. Data were taken on Plant height, Number of tillers, leaf length, Number of green leaves, Number of dead leaves, Leaf rolling score (LRS) and Rate of water loss. The salinity experiment was set up in a similar manner except that the plants were irrigated twice a day for 2 weeks with 200 ml of treatment solution containing either 0 mM NaCl or 75 mM and data were collected on plant height, number of tillers, shoot fresh weight, shoot dry weight, Na+ and K+ concentrations, relative water content and chlorophyll content. Data from both experiments were subjected to Analysis of variance test using the GenStat software 10th edition and the means separated using least significant difference test. Individual stress response index (ISRI) was calculated for each parameter and the means used in grouping the varieties. Of the genotypes evaluated, four (FARO 44, NERICA 2, NERICA 8 and NERICA 5) were identified as tolerant, two (NERICA 4 and FARO 57) as moderately tolerant, while the rest were found to be sensitive to drought. Equally, two varieties (FARO 44 and RAM 137) stood out in the salinity screening as tolerant varieties, five were moderately tolerant while four (FARO 64, FARO 52, NERICA 2 and FARO 55) were clearly susceptible. FARO 44 is the only genotype that showed tolerance to both drought and salinity. The identified drought and salinity tolerant rice genotypes from this study can be recommended as genetic sources for future breeding programs for drought and salinity tolerance in rice.

Predictive models of drought tolerance indices based on physiological,morphological and biochemical markers for the selection of cotton(Gossypium hirsutum L.)varieties

The use of tolerant crop varieties is a strategy that mitigates the water deficit effect in a sustainable way.The generation of these varieties is more efficient when variables associated with this tolerance have been identified,since they can facilitate the breeding processes.This study aimed to establish the relationships between water deficit tolerance of four cotton varieties(Nevada-123,Oasis-129,Guatapuri,and Festivalle)and morphological variables(monopodial branches,boll weight,root/shoot ratio,and leaf and root dry matter),physiological variables(relative water content,net photosynthesis,stomatal conductance,electron transport rate,photochemical quenching,photochemical efficiency of PSII,chlorophyll a/b ratio(Chl a/b),C^(12)/C^(13)isotope ratio,and electrolyte leakage),and biochemical variables(contents of sugars,proline,carotenoids,and malondialdehyde).Furthermore,calibrated predictive models of the drought tolerance indices were developed based on the key variables identified.For this purpose,a pot experiment was established where plants were subjected to a moderate or severe water deficit during the blooming stage for 12 days.The stress tolerance index(STI)and mean productivity(MP)were calculated.For the evaluated variables,the differences between well-watered and water deficit plants(Δ)were calculated and ANOVA,partial least squares,Pearson’s correlation,and multiple linear regression analyzes were performed.A model was generated that explained 95% of the STI and was composed of Δmalondialdehyde,Δproline,and Δboll weight.For MP,the model was comprised of Δstomatal conductance,Δroot/shoot ratio,and ΔChl a/b,and explained 89% of the MP.The analysis of the assessed variables allowed the identification of key variables and the development of calibrated predictive models that can be used in screening to obtain cotton varieties with different levels of water deficit tolerance.

Drought Tolerance Identification and Eevluation of Maize during Flowering Stage in Guangxi

Total 20 maize varieties were subjected to drought stress at flowering stage,and then the relative water content,soluble sugar content,chlorophyll content,malondialdehyde( MDA) content and superoxide dismutase( SOD) activity in their leaves,as well as their yields were determined. The drought tolerance of the physiological and biochemical indexes was scored by five-level scoring method,and the drought tolerance index was calculated by the yield index to comprehensively evaluate the drought tolerance of maize during flowering stage. The results showed that the scores of drought tolerance of the maize varieties ranged from 1. 929 3 to 5. 659 5. Among them,the scores of Zhengda 619,Guidan 162 and Guidan 0810 were greater than 5. 0,followed by Dika 008,Xianyu 30 T60,Xianzhengda 901,Qingnong 68,South America No. 1 and Wanchuan 1306 of which the scores were in the range of 4. 0-5. 0. The drought tolerance indexes were in the range of 0. 410 4-1. 096 3. Among the test maize varieties,the drought tolerance indexes of Guidan 0810,Pacific 99 and Zhengda 619 were greater than 1. 0,and those of Xianyu 30 T60,Dika 008 and South America No. 1 were in the range of 0. 9-1. 0. The correlation between the two kinds of evaluation results was 0. 588 7 and was extremely significant. The five-level scoring method and the drought tolerance index can be used simultaneously for the evaluation of drought tolerance of maize during flowering stage. The two aspects of evaluation results showed that Guidan 0810,Zhengda 619,Xianyu 30 T60,Dika 008 and South America No. 1 were drought-tolerant varieties,among which Guidan 0810 and Zhengda 619 were extremely highly drought-tolerant varieties.

玉米杂交种耐盐碱性的主成分分析及综合评价

【目的】筛选适合宁夏引黄灌区盐碱化土壤种植的耐盐碱玉米杂交种。【方法】采用宁夏农科院选育的30份玉米杂交种株高、穗位高、茎粗、穗长、穗粗、单穗质量、出苗率等14个性状指标,基于主成分分析和聚类分析综合筛选耐盐碱玉米杂交种。【结果】主成分分析结果表明,将14农艺性状转化成5个主成分因子,代表原始数据信息量85.57%,并选出单穗质量、穗行数、出籽率、茎粗、出苗率5个耐盐碱评价指标;宁禾1822、宁禾2021、宁禾1948、宁禾2035和先玉1225这5份玉米杂交种耐盐碱性较好。聚类分析将30份耐盐碱品种分为3种类型,结果与主成分分析基本一致。【结论】通过2种分析方法筛选出5份耐盐碱性较强的杂交种,给宁夏平罗盐碱地玉米种植提供理论参考。

3种我国造林树种幼苗耐盐性评价及指标筛选

[目的]研究苦楝、白榆和刺槐幼苗的耐盐性差异并筛选耐盐性评价指标。[方法]以1年生苦楝、白榆和刺槐幼苗为研究对象,设置0、100、200和300 mmol·L^(-1)NaCl处理,对各NaCl处理下3种幼苗的生物量、生理和生化指标进行分析。[结果](1) NaCl胁迫抑制了苦楝、白榆和刺槐幼苗的生物量,使其叶片相对含水量下降、电解质渗透率升高;(2)刺槐幼苗叶绿素含量随NaCl浓度升高而显著下降,但苦楝和白榆幼苗叶绿素a和叶绿素b含量仅在300 mmol·L^(-1)NaCl处理下显著降低;NaCl胁迫导致3种幼苗的光合作用参数Pn、Gs、Ci和E下降,而气孔限制值、水分利用效率、根和叶中游离脯氨酸和可溶性蛋白质含量、根和叶中CAT和APX活性升高;(3) NaCl胁迫改变了苦楝、白榆和刺槐幼苗体内的离子平衡状态,使3种幼苗根和叶中的Na+含量显著升高、叶中K^(+)含量升高;而根和叶中Mg^(2+)和Ca^(2+)以及根中K+含量的变化规律不完全一致。[结论]苦楝、白榆和刺槐幼苗耐盐能力强弱为白榆>苦楝>刺槐;根中游离脯氨酸和可溶性蛋白质含量、根和叶中CAT和APX活性、根中Ca^(2+)和叶中Na^(+)含量与苦楝、白榆和刺槐幼苗的耐盐性关联度较高,可作为耐盐性评价指标。

新疆鼠尾草和丹参对高温干旱胁迫的生理响应

为探究新疆鼠尾草(Salvia deserta Schang)和丹参(S.miltiorrhiza Bunge)对高温干旱胁迫的耐受性,设置常温(昼温27℃、夜温19℃)和高温(昼温42℃、夜温32℃)2个温度水平以及正常状态、中度干旱和重度干旱(土壤相对含水量分别为40%~45%、20%~25%和5%~10%)3个土壤含水量水平,对高温和干旱单一及复合胁迫下2种植物的受害指数、光合生理指标和抗逆生理生化指标的变化进行了比较。结果显示:随着胁迫时间延长,不同胁迫条件下2种植物的受害指数逐渐升高,总体来看,光合生理指标持续下降,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性先升高后降低,丙二醛(MDA)和脯氨酸(Pro)含量持续升高。与对照(昼温27℃、夜温19℃、土壤相对含水量40%~45%)相比,不同胁迫条件下2种植物的受害指数基本上显著(p<0.05)升高,多数光合生理指标显著降低,而多数抗逆生理生化指标则总体上显著升高。胁迫6 d,重度干旱单一胁迫(昼温27℃、夜温19℃、土壤相对含水量5%~10%)和重度复合胁迫(昼温42℃、夜温32℃、土壤相对含水量5%~10%)下2种植物的受害指数均显著高于其他胁迫条件,净光合速率、蒸腾速率、气孔导度、总叶绿素含量和叶绿素a含量与叶绿素b含量的比值(Chl a/b)总体上显著低于其他胁迫条件;重度复合胁迫下2种植物的SOD活性、MDA含量和Pro含量总体上显著高于其他胁迫条件。比较来看,不同胁迫条件下丹参的受害指数、胞间CO 2浓度、总叶绿素含量、MDA含量和Pro含量总体上低于新疆鼠尾草,净光合速率、蒸腾速率、气孔导度、Chl a/b值、SOD活性、POD活性、CAT活性和可溶性蛋白质含量总体上高于新疆鼠尾草。研究表明:新疆鼠尾草和丹参对高温干旱胁迫具有较强的耐受性,且丹参的耐受性更强。

Identifi cation of QTLs for Drought Resistance of Maize Germination and Seedling Development

In most maize-growing areas yield reductions due to drought have been observed (Frova et al., 1999; Li et al., 2003; Ribaut et al., 1997; Sari-Gorla et al., 1999). Seed germination and early seedling growth is the

不同棉花品种种子萌发期耐旱性综合评价

本试验选用45个黄淮棉区不同时期的代表性棉花品种为材料,采用15%PEG-6000溶液模拟干旱胁迫,测定各品种的种子发芽势、发芽率、发芽指数和单株干重、幼苗长度,计算5个萌发指标的相对值,分析各品种萌发指标的差异,并利用模糊隶属函数、相关分析等方法对45个棉花品种萌发期的耐旱性进行综合评价,为萌发期抗旱种质筛选及抗旱棉花新品种选育提供理论依据。结果表明,干旱胁迫抑制45个棉花品种萌发,品种间存在显著差异;相关分析显示,耐旱评价值与5个鉴定指标均呈正相关关系,与相对发芽势、相对发芽率、相对发芽指数呈极显著正相关;依据耐旱评价值将45个棉花品种分为高抗旱、抗旱、耐旱、不耐旱4个等级,其中高抗旱品种1个、抗旱品种7个、耐旱品种30个、不耐旱品种7个。说明过去或当前主栽棉花品种萌发期高抗旱及抗旱品种较少,为应对当前旱情加剧趋势,今后棉花育种需加强对萌发期抗旱品种的筛选。

Species-specific responses to drought,salinity and their interactions in Populus euphratica and P.pruinosa seedlings

Aims Drought and salinity are severe abiotic stress factors,which limit plant growth and productivity,particularly in desert regions.In this study,we employed two desert poplars,Populus euphratica Oliver and Populus pruinosa Schrenk seedlings,to compare their tolerance to drought,salinity and combined stress.Methods We investigated species-specific responses of P.euphratica and P.pruinosa in growth,photosynthetic capacity and pigment contents,nonstructural carbohydrate concentrations,Cl−allocation,osmotic regulation and the accumulation of reactive oxygen species(ROS)under drought,salinity and the combined stress.Important Findings Populus pruinosa exhibited greater growth inhibitory effects,photosynthesis decline,stomatal closure and ROS accumulation,and lower antioxidant enzyme activities and osmotic regulation compared with P.euphratica under drought,salinity and especially under their combined stress.On the other hand,salt-stressed P.euphratica plants restricted salt transportation from roots to leaves,and allocated more Cl−to coarse roots and less to leaves,whereas salt-stressed P.pruinosa allocated more Cl−to leaves.It was shown that there is species-specific variation in these two desert poplars,and P.pruinosa suffers greater negative effects compared with P.euphratica under drought,salinity and especially under the combined stress.Therefore,in ecological restoration and afforestation efforts,species-specific responses and tolerances of these two poplar species to drought and salinity should be considered under climate change with increasing drought and soil salinity developing.

高产、抗旱和耐盐选择对水稻产量相关性状的影响

水稻生产受到许多环境因素的胁迫,其中干旱和盐害是两大最重要的非生物逆境,培育抗旱和耐盐品种是减轻这两种逆境危害最经济有效的措施。利用籼型供体广恢122、Bg94-1和粳型供体原粳7号、沈农89366导入高产优质籼型品种丰矮占1号背景,创建BC3F5导入系群体,经目标性状筛选,以获得的2个高产抗旱导入系丰矮占1号/广恢122和丰矮占1号/原粳7号为亲本进行高产抗旱聚合,以高产耐盐导入系丰矮占1号/沈农89366和丰矮占1号/Bg94-1进行高产耐盐聚合。以聚合亲本为对照,在2个F2聚合群体中分别进行抗旱、耐盐、高产筛选,每个聚合群体分别获得30～42个不等的抗旱、耐盐和高产性状的极端个体,不同性状的选择强度变幅为8.3%～11.7%。3个目标性状极端选择后代在正常水田种植,其产量相关性状抽穗期、单株有效穗数、穗总粒数、穗实粒数、结实率、千粒重等均呈现明显的分离,各性状的变异方向因不同的选择群体和选择性状而异。在2个聚合组合的6个选择群体后代,有效穗数和每穗实粒数对单株产量的贡献最大,前者平均贡献率为18.5%,变幅为12.9%～27.4%,后者平均贡献率为13.1%,变幅为9.0%～21.2%。经过不同性状的交叉筛选,2个聚合组合的抗旱选择群体分别出现10.0%和36.7%耐盐的株系,其平均耐盐水平与耐盐选择群体相当,表明水稻抗旱和耐盐存在一定程度的遗传重叠。提出了利用回交导入系先进行抗旱、耐盐筛选,再进行产量选择和在此基础上对3个性状进一步聚合的高产抗旱和高产耐盐新品种培育策略。

植物脯氨酸及其合成酶系研究进展

脯氨酸在植物渗透调节中起着举足轻重的作用,本文就植物在胁迫逆境条件下脯氨酸的自然分布、合成、积累过程及合成酶分子生物学研究现状进行综述,并对已在GenBank中登录的脯氨酸基因家族成员进行了汇集整理。

河套灌区玉米耐盐性分析及生态适宜区划分

为了探讨河套灌区盐碱地玉米对根区土壤盐分的生态适应性,本文基于田间定位观测,运用非线性最小二乘数值逼近法建立玉米耐盐函数模型;同时根据耐盐性分析,提出玉米在该灌区不同生态适宜区的划分标准。结果表明,盐碱地地膜覆盖在生产上有较好的控盐效果,可以使玉米苗期0～10、0～20和0～40cm土壤盐分分别降低61.2%、53.8%、41.3%,能够增强玉米对盐碱地的生态适应性;分段式耐盐函数模型和S型耐盐函数模型均能较好地反应玉米相对产量对浅层土壤盐分变化的响应关系;浅层0～40cm土壤盐分作为玉米根层盐分来分析玉米的耐盐性最具代表性,其对应中玉9号玉米的耐盐指数为6.583;根据耐盐性分析,将区域耕地划分为玉米最适宜区、适宜区、次适宜区和不适宜区,对应玉米苗期0～20cm膜外土壤盐分分别为低于1.178、1.178～2.036、2.036～3.465和高于3.465g/kg。本研究将为当地玉米种植合理布局、高效生产提供理论指导。

玉米抗旱性与生理生化指标关系的研究

以目前我国主栽的14个玉米品种为试材,研究了玉米耐旱指数与生理生化指标的关系。结果表明,干旱胁迫下玉米耐旱指数与叶片相对含水量、脯氨酸含量及可溶性蛋白含量呈极显著正相关,与叶片相对电导率和可溶性糖含量呈极显著负相关,与叶片中丙二醛含量呈显著负相关。上述生理生化指标均可作为玉米抗旱性鉴定指标的参数,用于玉米品种抗旱性的评定。

大麦盐害及耐盐机理的研究进展

大麦是禾谷作物中较为耐盐的粮食作物。然而在盐胁迫环境下,Na+能把膜系统中的其他离子置换下来,使细胞过多地吸收Na+和Cl-,从而导致细胞膜系统受损、DNA降解、植物营养亏缺、生理干旱以及细胞死亡等伤害。大麦自身在受到盐分胁迫下,耐盐机制有:离子的选择性吸收、拒盐排盐性、渗透调节物质的合成以及离子在植株体内的运输交换。进行大麦耐盐性选择时,萌发力、耐盐指数、Na+/K+和渗透调节物质的合成能力,都是比较重要的选择标准。基于大麦较好的耐盐性,可通过遗传育种改良、化学控制、耕作等措施和途径提高大麦的耐盐抗盐能力,减轻盐害,提高大麦产量和品质。

黄土丘陵沟壑区典型植物耐旱生理及抗旱性评价

通过实地采样获取黄土高原丘陵区柠条、侧柏、油松、山杏和山毛桃5种常见植物类型的4个耐旱指标(丙二醛含量、叶绿素含量、谷胱甘肽含量、束缚水/自由水含量比值)和2个抗旱指标(脯氨酸含量、可溶性糖含量)数据,采用模糊数学隶属函数法和灰色关联分析法评价不同植物的抗旱能力和不同指标的指示效果。结果表明,不同树种的上述6个生理指标对干旱条件的响应存在显著差异,但基于单个指标获得的树种抗旱能力排序结果不完全一致,说明单个指标无法全面描述树种的抗旱能力,对5个树种抗旱能力大小的综合评价结果为柠条>侧柏>油松>山杏>山毛桃。耐旱指标叶绿素含量、束缚水/自由水含量比值、谷胱甘肽含量和抗旱指标脯氨酸含量与抗旱隶属度的关联度值均>0.60,可用以指示植物的抗旱能力,其中,以脯氨酸含量的指示效果最好。

地被菊花幼苗耐旱性评价方法研究

选用地被菊品种White Snow 10 叶龄扦插生根幼苗进行自然失水胁迫和PEG 胁迫处理。划分了不同处理萎蔫指数,测定了鲜样质量保持率、叶片水势、叶片溶质渗透势、丙二醛(MDA)含量、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性。结果表明,萎蔫指数划分的主要形态特征因胁迫方法而异。自然失水胁迫8 h 为幼苗恢复极限;在恢复极限内复水,幼苗鲜样质量保持率、叶片水势、MDA 含量和SOD 以及CAT 活性的变化规律显著。20%PEG 胁迫4 h 为恢复极限;复水期间的鲜样质量保持率、叶片溶质渗透势、MDA 含量和SOD 活性的变化规律显著。综合上述,这2 种方法都可以用于地被菊花幼苗耐旱性快速评价;不同的胁迫处理方式可利用的水分状况和生理指标存在一定的差异。

盐分胁迫对林木种子发芽率的影响研究

试验研究盐分胁迫对林木种子发芽率的影响结果表明 ,NaCl和NaCl+KCl 2种盐分对林木种子发芽率和苗木生长均有一定抑制作用 ;随盐分浓度的提高而发芽率逐渐下降 ,幼苗生长呈相同趋势。与复合盐分相比 ,单一盐分对种子发芽和苗木生长抑制作用更强 ,表明K+ 可一定程度缓解Na+ 的危害 。

不同甘薯品种抗旱性评价及耐旱指标筛选

在人工控水条件下,以15个甘薯品种为试验材料,设置干旱胁迫和正常灌水2个处理,研究了干旱胁迫条件下不同甘薯品种产量和农艺性状差异。根据产量抗旱系数法分级,抗旱品种(抗旱系数≥0.6)为济薯21、济薯25、济徐23、济薯15、烟薯25;中等抗旱品种(0.4≤抗旱系数<0.6)为徐薯18、济薯26、北京553、济紫薯2号、济薯18;不抗旱品种(抗旱系数<0.4)为郑薯20、济紫薯3号、济薯22、济紫薯1号、凌紫。干旱胁迫导致甘薯的叶片数、蔓长、叶面积系数和生物量下降,品种间降幅不同,抗旱性强的品种降幅小,抗旱性弱的品种降幅大。这些农艺性状指标与甘薯品种的抗旱性呈显著正相关,可作为甘薯品种抗旱性鉴定的指标。徐薯18可作为甘薯品种抗旱性鉴定的标准品种。