Effect of silicon on photosynthetic gas exchange,photosynthetic pigments,cell membrane stability and relative water content of different wheat cultivars under drought stress conditions

This study aims to explain the effects of silicon (Si) foliar application on gas exchange characteristics, photosynthetic pigments, membrane stability and leaf relative water content of different wheat cultivars in the field under drought stress conditions. The experiment was arranged as a split-split plot based on randomized complete block design with three replications. Irrigation regime (100%, 60%, and 40% F.C.), silicon (control and Si application) and wheat cultivars (Shiraz, Marvdasht, Chamran, and Sirvan) were considered as main, sub and sub-sub plots, respectively. This study was carried out at the Research Farm of the Collage of Agriculture, Shiraz University, Iran, during 2012–2013 growing season. The results showed that foliar application of silicon increased the leaf relative water content, photosynthesis pigments (chlorophyll a, b and total chl and carotenoids), chlorophyll stability index (CSI) and membrane stability index (MSI) in all wheat cultivars, especially in Sirvan and Chamran (drought tolerant cultivars), under both stress and non-stress conditions. However, more improvement was observed under drought stress as compared to the non-stress condition. In contrast, these parameters decreased under drought stress. Si significantly decreased electrolyte leakage in all four cultivars under drought stress conditions. Furthermore, the intercellular carbon dioxide (CO₂) concentration (C_i) increased under drought stress. Si application decreased C_i especially under drought stress conditions. Net photosynthesis rate (A), transpiration rate (E) and stomatal conductance (g_s) were significantly decreased under drought conditions. Under drought, Si applied plants showed significantly higher leaf photosynthesis rate, transpiration rate, and stomatal conductance. Intrinsic water use efficiency (WUEi) and carboxylation efficiency (C_E) decreased in all cultivars under drought stress. However, the silicon-applied plants had greater WUEi and C_E under drought stress. The stomatal limitation was found to be higher in stressed plants compared to the control. Exogenously applied silicon also decreased stomatal limitation. Overall, application of Si was found beneficial for improving drought tolerance of wheat plants.     

Effects of green synthesized zinc and copper nano-fertilizers on the morphological and biochemical attributes of basil plant

Abstract

In the present study, the green synthesis of Zn and Cu nanoparticles (NPs) was carried out via Zn and Cu ions reduction during their exposure to basil extract. The shape, size and chemical identity of the Zn and Cu NPs were determined using SEM and XRD analysis. To investigate the effects of the Zn and Cu NPs on the morphological and biochemical traits of basil plant, an experiment was conducted as a factorial based on completely randomized design with 4 levels of Zn NPs (0, 1000, 2000, and 4000?ppm) and 4 levels of Cu NPs (0, 1000, 2000, and 4000?ppm). Based on the results, nutrient treatments, especially 4000?ppm Zn NPs + 2000?ppm Cu NPs caused a significant increase in most morphological parameters. The application of the Zn and Cu NPs significantly affected concentrations of chlorophyll a, chlorophyll b, total chlorophyll and carotenoid in the leaves of basil plants. The highest total phenolic and flavonoid content was obtained for 4000?ppm Zn NPs + 2000?ppm Cu NPs treatment. Plants treated with 4000?ppm Zn NPs + 0?ppm Cu NPs showed the highest antioxidant activity followed by 4000?ppm Zn NPs + 2000?ppm Cu NPs and 2000?ppm Zn NPs + 0?ppm Cu NPs. It can be concluded that foliar application of the Zn and Cu NPs is necessary for obtaining better quantity and quality in basil.     

Amelioration of drought stress in wheat by combined application of PGPR,compost, and mineral fertilizer

Among various abiotic stresses, global drought reduces global growth and yield of wheat. Present research has been designed to ameliorate the adverse effects of drought stress on wheat by combined application of plant growth-promoting rhizobacteria (PGPR), compost, and mineral fertilizers. In this experiment, the role of fertilizer, compost, and PGPR inoculation to ameliorate drought stress was studied in two wheat varieties at vegetative stage. Water stress adversely affects morphology, physiology, and biochemistry of the wheat plant. Inoculated seed with compost and mineral fertilizer grown in drought condition showed 43% increase in relative water content (RWC) of 9.39% in Membrane Stability Index and 82.20% in chlorophyll as compared to control. Drought affected the accumulation of osmolytes, but PGPR in combination with compost and mineral fertilizer under drought stress triggered higher accumulation of soluble sugar and proline content, i.e., 28.96% and 73.91%, respectively. It is concluded from this research that PGPR in combination with compost and mineral fertilizer considerably reduces the effect of drought on wheat by enhancing the physiological (RWC, membrane stability, chlorophyll content, and water potential) and biochemical (proline and sugar) aspects of the plant.     

Response of maize (Zea mays L.) to potassium nano-silica application under drought stress

Abstract

To investigate the influence of potassium nano-silica (PNS) on maize plant under drought stress including non-stress (NS), moderate drought stress (MDS) and severe drought stress (SDS), a factorial experiment was conducted with completely randomized blocks with three replications. Drought stress decreased the concentrations in the shoot of phosphor (P), calcium (Ca), iron (Fe), zinc (Zn), manganese (Mn) and silica (Si) and nitrogen (N), P, Ca, Fe, Zn, copper (Cu), Mn and Si concentrations of seed. There was an increase in the concentration in the N seed and shoot potassium (K) concentration under drought stress. It was observed that applying PNS increased nutrient absorption. The highest concentration of N in the seed was obtained at 100?ppm PNS. The highest concentrations of seed K and N, Cu, Mn and Si in the shoot were found when 200?ppm of PNS was applied. Applying PNS had no significant effect on the concentrations of P, Ca, sodium (Na) and Cu in the seed, and of Ca and Na in the shoot. These findings demonstrate that the application of PNS can limit the negative effects of drought stress and improve plant’s resistance against drought stress.     

Water stress effects on biochemical traits and antioxidant activities of wheat (Triticum aestivum L.) under In vitro conditions

Water stress is one of the major environmental stresses that affect agricultural production worldwide, especially in arid and semi-arid regions. This research investigated the effect of water deficit, induced by PEG-6000 on wheat genotypes (GA-2002, Chakwal-97, Uqab-2000, Chakwal-50 and Wafaq-2001) grown in modified MS medium solution. Osmotic stress caused a more pronounced inhibition in leaf relative water content and leaf membrane stability more sensitive (index in Wafaq-2001 and Uqab-2000) genotypes compared with the tolerant (Chakwal-50, GA-2002 and Chakwal-97) genotypes. Upon dehydration, an incline in proline, total soluble sugar, total soluble protein, superoxide dismutase, peroxidase, catalase and malondialdehyde activity content were evident in all genotypes, especially at osmotic stress of ?8 bars. The observed data showed that status of biochemical attributes and antioxidant enzymes could provide a meaningful tool for depicting drought tolerance of wheat genotypes. The present study shows that genotypic differences in drought tolerance could be likely attributed to the ability of wheat plants to induce antioxidant defense under drought conditions. In order to develop genotypes with stable, higher yields in dry farming conditions, it is necessary to characterise genetic resources based on drought adaptation, determine suitable genotypes, and then use them in breeding programmes.     

Evaluation of assimilate remobilization and yield of wheat cultivars under different irrigation regimes in an arid climate

To investigate the effects of irrigation regimes on assimilate remobilization, water use efficiency (WUE), relative water content (RWC), photosynthesis and yield of five wheat cultivars, a field experiment was conducted at Shiraz University during the 2008 and 2009 growing seasons. The experimental design was a randomized complete block and treatments were arranged as split-plot in three replicates. There were four levels of water regime including well-watered [irrigation based on 100% field capacity (FC)], excess watered (125% FC), mild drought (75% FC) and severe drought (50% FC) stress, and four bread wheat cultivars (Shiraz, Bahar, Pishtaz and Sistan) and a durum wheat (Yavaros). In all cultivars, progressed leaf senescence at 30 days after anthesis (DAA), was associated with a reduction in chlorophyll content. The reduction was more pronounced in Shiraz and Yavaros than Pishtaz and Sistan. With increasing temperature and remobilization of assimilate to grain, net photosynthesis and stomatal conductance were decreased significantly at 18 DAA compared with 8 DAA. Sistan and Pishtaz cultivars maintained higher RWC than sensitive cultivars of Shiraz and Yavaros under drought stress. The higher WUE in Pishtaz and Sistan was attributed to the effectiveness of a small amount of water in alleviating severe stress during the sensitive stages of growth. Under mild drought stress, controlled soil drying could enhance remobilization efficiency of assimilates in Pishtaz and Sistan and under severe drought, these cultivars had the highest grain yield compared with the other cultivars. Reduction of assimilates remobilization to the grain and 1000-grain weight, caused lower grain yield in Shiraz under severe drought. Overall, controlled soil drying in Sistan and Pishtaz might result in better mobilization of pre-stored assimilates to the grain in arid areas, where a rapid depletion of water resources is threatening crop production.     

Foliar application of silicon at different growth stages alters growth and yield of selected wheat cultivars

To evaluate the response of some selected wheat cultivars to silicon application at different growth stages under drought stress, an experiment was carried out in the greenhouse of College of Agriculture, Shiraz University, Iran, during 2012 using a completely randomized factorial design with four replications. Experimental treatments included drought stress (100% F.C. as control and 40% F.C. as drought) and foliar application of 6 mM sodium silicate (control, application at mid tillering stage, at anthesis stage, and application at tillering + anthesis stages) and wheat cultivars (Sirvan and Chamran, relatively drought-tolerant, and Shiraz and Marvdasht, drought-sensitive cultivars). Drought stress significantly reduced chlorophyll content, leaf area, relative water content, grains per spike, 1000-grain weight, grain yield and biomass of all wheat cultivars. Furthermore, drought stress increased electrolyte leakage of the flag leaves of all cultivars. In contrast, foliar-applied silicon significantly increased these parameters and reduced electrolyte leakage. Furthermore, highest positive influence of silicon application was observed at combined use of silicon both at the tillering + anthesis stages in wheat plants under both stress and non-stress conditions. Significant differences were found in physiological responses among wheat cultivars. The drought tolerant cultivars (Sirvan and Chamran) had significantly higher growth and yield than those of drought sensitive cvs. Shiraz and Marvdasht under drought stress. In conclusion, foliar application of silicon especially at the tillering + anthesis stages was very effective in promoting resistance in wheat plants to drought conditions by maintaining cellular membrane integrity and relative water content, and increasing chlorophyll content.     

冬小麦光合特性对CO2浓度与土壤含水量的响应机制

光合作用是衡量植物对环境响应的重要指标,通过光响应曲线拟合量化光合特征,可从生理机制方面揭示出植物在不同生长环境下自身的调节与适应机制。本文利用Li-6400便携式光合仪测定了冬小麦在4种不同处理条件下灌浆期旗叶的光响应曲线,采用直角双曲线模型(RHM)、非直角双曲线模型(NRHM)、直角双曲线修正模型(RHMM)、指数模型(EM)和指数改进模型(MEM)对光响应数据进行拟合,分析了不同CO_2浓度和土壤含水量对冬小麦光合特征的影响。结果表明,直角双曲线修正模型对各处理下冬小麦光响应曲线和光响应曲线参数的拟合值都与实测值较为接近,拟合效果最好;随着CO_2浓度升高,各水分处理下冬小麦表观量子效率(α)、光饱和点(LSP)和最大净光合速率(P_(nmax))增大,光补偿点(LCP)和暗呼吸(R_d)降低,即CO_2浓度升高能有效增加冬小麦的光能转化率和光能利用范围,提高冬小麦的光合能力;随着土壤含水量的降低,冬小麦光补偿点(LCP)和暗呼吸速率(R_d)升高,但表观量子效率(α)、光饱和点(LSP)和最大净光合速率(Pnmax)降低,即冬小麦虽然能通过提高初始光合效率抵消一部分干旱胁迫的影响,但干旱胁迫仍会降低冬小麦光合能力;此外,CO_2浓度的增加能抵消部分冬小麦因干旱胁迫引起的光合能力降低。     

干旱与Cd双重胁迫对土壤-小麦-蚜虫系统Cd转移规律影响的研究

为探究干旱和重金属双重胁迫对土壤-小麦-蚜虫系统内Cd转移规律的影响,为小麦蚜虫的生态调节提供理论依据,本研究以麦长管蚜[Sitobionavenae(Fabricius)]为研究对象,用原子吸收分光光度法分别测定不同土壤Cd含量(100 mg?kg-1、200 mg?kg-1)及不同程度干旱胁迫(无胁迫、中度胁迫、重度胁迫)处理下小麦根茎叶及蚜虫体内的Cd含量。结果表明:土壤Cd含量及干旱单一胁迫均对小麦及蚜虫体内的Cd含量造成了显著影响(P0.05)。两者交互作用对小麦根部及叶部的Cd含量影响显著,而对小麦茎部及蚜虫体内Cd含量影响不显著。在相同胁迫条件下, Cd在小麦中的积累分布为根茎叶。随着干旱胁迫程度增大,小麦根部Cd含量及土壤-根转移系数降低,茎部Cd含量及根-茎转移系数升高,麦长管蚜Cd含量在土壤Cd含量100mg?kg-1下高于土壤Cd含量200 mg?kg-1;中度干旱胁迫增加了麦长管蚜体内Cd累积量,而重度干旱胁迫则降低了其体内Cd累积量。叶-蚜虫的Cd转移系数明显大于土壤-根、根-茎和茎-叶转移系数且大于1,说明Cd在麦长管蚜体内产生了生物富集作用。综上所述,干旱胁迫促进了Cd从土壤向小麦茎部转移和根部Cd累积,但抑制了Cd从根部到茎部转移和茎部Cd累积;中度干旱胁迫促进了麦长管蚜体内Cd的积累,而重度干旱胁迫抑制了麦长管蚜体内Cd的积累。     

氮肥缓解苗期干旱对小麦根系形态建成及生理特性的影响

为揭示氮肥缓解苗期干旱对小麦根系生长的影响,以高产高蛋白品种Spitfire(S)和抗旱品种Drysdale(D)为材料,采用沙培方式研究了不同氮素处理(180和22.5 kg·hm^-2)和水分处理(干旱和正常浇水)对苗期小麦根系形态建成和生理生长的影响。结果表明,苗期干旱下增施氮肥减小了2个品种小麦根系总根长、根系表面积、总根体积、根尖数和分枝数,显著增加了根系直径和根系活力,S品种根系干重减小7.0%,而D品种根系干重增加12.0%。施高氮还降低了干旱下2个品种小麦根系可溶性糖含量,并提高了游离氨基酸含量,且耐旱性品种D变化幅度较大,2个品种根系可溶性蛋白含量的变化均不明显。此外,增施氮肥能促进根系对氮素的吸收,提高根系硝酸还原酶(NR)活性和含氮量。综上,在苗期干旱下增施氮肥能够促进小麦根系生长,提高根系活力和NR活性,以增强根系对氮素的吸收同化能力,促进氮代谢水平,从而提高小麦的抗旱性,但不同耐旱品种对干旱下增施氮肥的响应程度存在差异。本研究结果为通过增施氮肥有效缓解干旱进而提高小麦产量提供了理论依据。     

Effects of drought stress on some agronomic and bio-physiological traits of Trititicum aestivum,Triticale, and Tritipyrum genotypes

ABSTRACT

Drought tolerance is a complex trait that involves different biochemical and physiological mechanisms in plants. It was the objective of the present study to evaluate the agronomic and biochemical responses of triticale, tritipyrum, and wheat to drought stress. For this purpose, twenty-seven genotypes were evaluated under two levels (non-stress and drought stress) of irrigation during 2015?2017. The metabolic traits studied included relative water content (RWC), membrane stability index (MSI), chlorophyll a (Chla), chlorophyll b (Chlb), carotenoids (Car), leaf proline content (Pro), leaf soluble carbohydrates (LSC), glycine betaine (GB), malondialdehyde (MDA), hydrogen peroxide (H₂O₂), seeds per spike (SS), seed weight (SW), biological yield (BY) and seed yield (SY). Drought stress increased Pro, LSC, and GB contents as well as lipid peroxidation through increasing MDA and H₂O₂ activities. However, both RWC and MSI indices as well as SS, SW, SY and BY reduced as a result of drought treatment although the least decrease of SY was observed at triticale group. During the two years of study, the tritipyrum genotypes exhibited their drought tolerance by accumulation of more LSC and GB as well as lower decrease in SW while the triticale ones responded by maintaining higher levels of RWC but producing less MDA and H₂O₂. It may, therefore, be concluded that the three species studied exploit different mechanisms to maintain tolerance against drought stress. Finally, correlation analysis indicated the positive effects of LSC on SY under both drought and normal conditions, which is obviously a promising trait in wheat, triticale, and tritipyrum that can be beneficially exploited in drought tolerance improvement programs.     

Interactive effect of salinity and silver nanoparticles on photosynthetic and biochemical parameters of wheat

The present study investigated the influence of seed priming with silver nanoparticles (Ag NPs), 0, 2, 5 and 10 mM, on growth and biochemical parameters of wheat (Triticum aestivum L.) under salt stress. As expected, 150 mM of NaCl decreased the shoot fresh and dry weights and chlorophyll contents and increased the catalase (CAT) and peroxidase (POD) activities. Salinity enhanced the concentration of proline, soluble sugars, malondialdehyde and hydrogen peroxide. Seed priming with Ag NPs increased the shoot fresh and dry weight of normal and salt-stressed plants. Lower concentration of Ag NPs decreased the total soluble sugars and proline contents, while the higher Ag NPs levels increased these contents compared to the control. The combined application of Ag NPs and salt stress increased the soluble sugars and proline contents, while it decreased CAT activity and increased POD activity compared to the respective Ag NPs treatments alone. Overall, our results demonstrated that Ag NPs enhanced the salt tolerance in wheat, but the long-term response of Ag NPs under salt stress needs further investigation.     

纳米氧化铜对小麦根系生理生化行为的影响

为阐明纳米金属材料暴露对植物生长的影响及其作用机制,采用模拟土壤的琼脂培养方法研究了纳米氧化铜(CuO NPs)对小麦(Triticum aestivum L.)根伸长及相关生理生化行为的影响。结果表明:小麦根伸长与CuO NPs暴露浓度之间存在指数相关关系,在低浓度CuO NPs(10 mg/L)暴露下得到一定程度促进,而在高浓度(100 mg/L)下受到强烈抑制。小麦根内超氧化物歧化酶(SOD)活性随CuO NPs暴露浓度的变化趋势与小麦根伸长具有一致性。另外,在1~100 mg/L范围内,随着CuO NPs暴露浓度的升高,小麦根内丙二醛(MDA)含量不断增加,但植物蛋白含量急剧降低。以上结果说明CuO NPs对根伸长抑制主要是由于纳米材料暴露造成植物细胞膜氧化损伤,小麦能通过提高根系活力对CuO NPs暴露作出适应性应激响应以减少纳米材料毒性的伤害。     

褪黑素壳聚糖微粒防止褪黑素降解并有效提高其抗旱功能

  【目的】  褪黑素可提高作物抗旱性,但容易降解。本研究试图开发具有缓释和抵御光降解能力的褪黑素壳聚糖微粒,并对其抗旱性进行评价。  【方法】  利用壳聚糖与三聚磷酸钠和果胶所产生的静电引力,使三者之间产生交联形成包裹褪黑素的杂化微粒,从而实现褪黑素的缓释和保活。确定投入褪黑素质量为5 mg时制备的褪黑素壳聚糖微粒作为试验材料(MP-MT)。利用扫描电子显微镜(SEM)和傅立叶变换红外光谱(FTIR),对褪黑素壳聚糖微粒(MP-MT)表面形貌及官能团特性进行表征。采用超高效液相色谱技术,探究MP-MT对褪黑素的缓释性能和抵抗光降解的性能。以两叶一心的小麦幼苗为试材,进行灌根试验。将基质最大持水量的80%设为正常对照(CK1),基质最大持水量的40%设为干旱对照(CK2);在干旱胁迫下,设施用1.0 g/L褪黑素(MT1.0)、壳聚糖微粒(MP)和含褪黑素0.5、1.0、1.5 g/L的褪黑素壳聚糖微粒(MP-MT0.5、MP-MT1.0、MP-MT1.5),共7个处理。在处理后第8天,取样分析小麦幼苗株高、干重、鲜重、叶片SPAD值、根系生长、抗氧化酶活性及丙二醛含量。  【结果】  当褪黑素投入量为5 mg时MP-MT对褪黑素的包封率最稳定,为52.14%,之后的相关试验均以该比例制备的褪黑素壳聚糖微粒(MP-MT)作为试验材料。通过SEM照片发现,MP-MT微粒粒径相较于壳聚糖微粒增加且表面变粗糙。MP-MT微粒FTIR结果同时检测出现了壳聚糖、褪黑素等组分的特征峰,表明褪黑素在微粒中存在。模拟释放试验结果表明,MP-MT在pH 5.0和pH 7.0磷酸缓冲溶液下36 h的释放率分别为65.43%、50.13%。模拟光降解试验表明,可见光照射4 h时MP-MT中褪黑素的光降解率较普通MT降低了143.37%。小麦幼苗干旱胁迫试验结果表明,与MT1.0处理相比,3个MP-MT处理的小麦幼苗干重增加4.50%～22.73%,根系长度增加15.92%～32.56%,过氧化酶活性提高19.56%～20.34%,丙二醛含量降低9.77%～12.30% (P<0.05)。  【结论】  壳聚糖/三聚磷酸钠/果胶的褪黑素封装体系可以实现褪黑素的缓释和保活,显著提高干旱胁迫下小麦幼苗SPAD值,促进根系发育,提高抗氧化酶活性,从而提高小麦幼苗抗旱性。     

CO2浓度升高、氮和水分对春小麦养分吸收和土壤养分的效应

研究了 2种CO2浓度水平 ,2种土壤水分处理和 5种N肥施用水平对春小麦 (TriticumaestivumL cv DingxiNo. 8654)养分吸收和土壤速效养分的影响。结果表明 ,高CO2浓度 (700 molmol-1)明显降低春小麦对氮(N)的吸收 ,低N时降低更为明显 ,但对磷 (P)、钾 (K)吸收的影响不明显。小麦对N、P、K吸收 ,干旱处理明显比湿润处理低。CO2浓度增高对土壤速效N的影响与土壤水分状况有关。湿润处理 ,CO2浓度增加的处理速效N量比当前CO2浓度的处理低 ;而干旱处理 ,施N 50、100、150mgkg-1时 ,速效N则较高。高CO2 浓度对土壤速效P、K量的影响不明显 ,而低N和水分不足 ,土壤速效P、K量较高     

Effect of temperature, elevated carbon dioxide, and drought during seed development on the isoflavone content of dwarf soybean [Glycine max (L.) Merrill] grown in controlled environments

The effects of elevated temperature, carbon dioxide, and water stress on the isoflavone content of seed from a dwarf soybean line [Glycine max (L.) Merrill] were determined, using controlled environment chambers. Increasing the temperature from 18 degrees C during seed development to 23 degrees C decreased total isoflavone content by about 65%. A further 5 degrees C increase to 28 degrees C decreased the total isoflavone content by about 90%. Combining treatments at elevated temperature with elevated CO(2) (700 ppm) and water stress to determine the possible consequences of global climate change on soybean seed isoflavone content indicated that elevated CO(2) at elevated temperatures could partially reverse the effects of temperature on soybean seed isoflavone content. The addition of drought stress to plants grown at 23 degrees C and elevated CO(2) returned the total isoflavone levels to the control values obtained at 18 degrees C and 400 ppm CO(2). The promotive effects of drought and elevated CO(2) at 23 degrees C on the 6' '-O-malonygenistin and genistin levels were additive. The individual isoflavones often had different responses to the various growth conditions during seed maturation, modifying the proportions of the principal isoflavones. Therefore, subtle changes in certain environmental factors may change the isoflavone content of commercially grown soybean, altering the nutritional values of soy products.     

花后土壤干旱和渍水对不同专用小麦籽粒品质的影响

在温室盆栽条件下,以4个籽粒蛋白质含量不同的小麦基因型为材料,研究了花后土壤干旱(SRWC=45%～50%)、渍水和适宜水分条件(SRWC=75%～80%)下小麦籽粒主要品质特性。干旱显著提高各品种籽粒蛋白质含量、谷蛋白含量及谷蛋白/醇溶蛋白比值,并显著提高面粉干/湿面筋含量。渍水显著降低了籽粒谷蛋白含量及谷蛋白/醇溶蛋白比值。干旱和渍水均显著降低籽粒淀粉产量和支链淀粉含量,直链淀粉含量提高,从而不同程度地降低籽粒直/支链淀粉比。干旱和渍水对各品种籽粒面筋指数、沉降值和降落值的影响因品种而异。与对照相比,干旱和渍水下小麦籽粒各品质性状间的相关性降低,表明土壤水分逆境下各籽粒品质特征值与正常水分条件下差异明显,从而改变了专用小麦的籽粒品质特性。     

硅对干旱胁迫下小麦幼苗生长及光合参数的影响

采用溶液培养试验,以两个抗旱性不同的小麦品种:低抗的扬麦9号(Yangmai.9)和高抗的豫麦18(Yumai.18)为材料,用PEG6000(聚乙二醇6000,渗透势约为-0.589MPa)模拟干旱胁迫条件,研究了硅对干旱胁迫下小麦幼苗生长、光合作用及可溶性糖含量的影响。结果表明,干旱胁迫条件下,小麦幼苗的生长和光合作用显著受到抑制,加硅处理能有效地提高干旱胁迫条件下小麦幼苗的生长状况及光合作用,且1.0.mmol/L.Si处理的效果优于0.1mmol/L.Si处理。与不加硅处理相比,干旱胁迫条件下加硅处理后,小麦幼苗的鲜干重、叶片可溶性蛋白含量、净光合速率(Pn)、蒸腾速率(Tr)、水分利用率(WUE)和气孔限制值(Ls)均显著升高,叶绿素含量也有一定程度的升高;而气孔导度(Gs)和细胞间隙CO2浓度(Ci)显著下降,可溶性糖积累量也降低。因此,硅可显著提高小麦对干旱胁迫的抗性。     

不同品种葡萄叶片光合特性对干旱胁迫的响应及旱后恢复过程

以设施葡萄品种“巨峰”和“夏黑”为试材,设置5个不同的干旱胁迫组：T1（干旱胁迫3d）,T2（干旱胁迫6d）,T3（干旱胁迫9d）,T4（干旱胁迫12d）和T5（干旱胁迫15d）,以正常水分处理组为CK（土壤相对含水率70%～80%）,研究干旱胁迫下葡萄叶片的光合荧光参数变化,以及不同程度干旱胁迫后水分恢复处理下的叶片恢复情况。结果表明：干旱可降低葡萄叶片的光合参数和荧光参数,且巨峰的变化幅度大于夏黑。在15d的干旱胁迫中,巨峰的光合参数下降70%～90%,夏黑下降60%～80%;葡萄叶片的荧光参数中,F0随着干旱胁迫的加剧而显著上升,而qP、Fv/Fm、ETR和ΦPSⅡ则随着干旱胁迫加剧而降低。其中巨峰叶片的ΦPSⅡ、qP和ETR在15d的干旱胁迫中分别下降40.63%、43.24%和57.71%,F0上升48.27%。夏黑叶片的ΦPSⅡ、qP和ETR在15d的干旱胁迫中分别下降26.38%、40.00%和59.69%,F0则上升50.19%。葡萄叶片的旱后恢复过程,在胁迫程度较轻时（T1-T4）,夏黑叶片的光合参数恢复能力大于巨峰,胁迫程度较重（T5）时则相反;两个葡萄品种荧光参数的恢复程度差异不显著。     

Improvement in seed quantity and quality of spring safflower through foliar application of boron and zinc under end-season drought stress

Seed yield and quality are affected by water stress occurring at the reproductive stage of crops. Foliar application of micronutrients has been introduced as an agronomic approach to cope with such conditions. This study was undertaken to evaluate the effects of born (B) and zinc (Zn) on seed quantity and quality of spring safflower under late season water deficit. The experimental design was a split factorial in an randomized complete block (RCB) with three replications. The results showed that water deficit during flowering and seed-filling significantly decreased almost all traits compared to control only in 2014. Averaged over the 2 years, seedling length and vigor index were increased by Zn in all irrigation regimes. Germination rate and seed weight were increased by B and Zn in all irrigation treatments. It was concluded that foliar application of 350?ppm B and 1000?ppm Zn can considerably enhance seed yield and quality of safflower grown under terminal drought.