2,4-表油菜素内酯对亚适温弱光下黄瓜幼苗光合特性和抗氧化系统的影响

为了探讨外源2,4-表油菜素内酯(EBR)对亚适温弱光(18/12℃,光照80μmol·m~(-2)·s~(-1))下黄瓜幼苗生长的调节作用,以优博1-5为试材,以常温喷施清水为对照,采用叶面喷施EBR的方法,研究其对叶绿素含量、光合气体交换参数、叶绿素荧光参数、碳同化关键酶活性和抗氧化酶活性的影响。结果表明,亚适温弱光下黄瓜幼苗的净光合速率(Pn)和叶绿素相对含量(SPAD值)分别比对照显著降低53.61%和21.73%,丙二醛(MDA)含量增加78.90%,进而导致干物质积累减少。亚适温弱光下喷施0.1μmol·L~(-1)EBR后,比叶重、Pn、SPAD值、光系统Ⅱ最大光化学效率(Fv/Fm)、光系统Ⅱ实际光化学效率(ΦPSⅡ)和光化学猝灭系数(q P)显著增加,非光化学猝灭系数(NPQ)减小,同时核酮糖-1,5-二磷酸羧化/加氧酶(Rubisco)、景天庚酮糖-1,7-二磷酸酯酶(SBPase)、转酮醇酶(TK)和果糖-1,6-二磷酸醛缩酶(FBA)活性明显升高,抗氧化酶(SOD、POD、CAT)活性显著增加,膜脂过氧化程度减轻。由此可见,外源EBR可以通过提高叶绿素含量、光化学效率和碳同化关键酶活性改善亚适温弱光下黄瓜幼苗的光合性能,并通过提高抗氧化酶活性以降低膜脂过氧化伤害,从而有效缓解亚适温弱光对黄瓜幼苗的伤害。本研究结果为阐明EBR缓解黄瓜幼苗亚适温弱光胁迫的调控机制提供了一定理论依据。     

2,4-表油菜素内酯对低温胁迫下辣椒幼苗根系生长及抗氧化酶系统的影响

为探讨外源2,4-表油菜素内酯(2,4-epibrassinolide,EBR)对低温胁迫下辣椒(Capsicum annuum L.)幼苗根系的生长和根系抗氧化系统的影响,本试验采用叶面喷施外源EBR(0、10.0、1.0、0.1、0.01、0.001 μmol·L-1)的方法,比较分析了低温胁迫下幼苗根系形态、根系抗氧化酶活性、过氧化物质含量等生理指标.结果表明,低温抑制了辣椒幼苗根系的生长,低温胁迫下喷施EBR,辣椒幼苗根系的生长受抑制程度减轻,其根系总长、根表面积、分根数较单纯低温处理显著增加;低温胁迫下喷施0.1μmol·L-1EBR辣椒幼苗根系SOD、POD、CAT活性显著提高,MDA含量降低.外源EBR处理可调节辣椒根系形态和提高根系抗氧化酶活性,增强植株抗低温胁迫的能力,并且EBR的浓度以0.1μmol·L-1最佳.说明在低温胁迫下适宜浓度的EBR可缓解辣椒幼苗的根系生长,这对阐明EBR缓解辣椒幼苗低温胁迫的作用机制提供了理论依据.     

2,4-表油菜素内酯结合氯化钙处理对采后杏果实黑斑病及苯丙烷代谢的影响

为探究减轻杏果实采后黑斑病的方法,以赛买提杏果实为试验材料,经3.0 mg·L^-1 2,4-表油菜素内酯(EBR)结合2%氯化钙(CaCl₂)减压渗透处理后,于温度1.0±1℃、相对湿度90%~95%条件下放置48 h后,进行交孢链格孢(Alternaria alternata)损伤接种,并进行A. alternata离体抑菌试验。结果表明,3.0 mg·L^-1 EBR结合2% CaCl₂对A. alternata的菌落直径和孢子萌发没有直接抑制作用。EBR结合CaCl₂处理可通过诱导苯丙氨酸解氨酶(PAL)、肉桂酸-4-羟化酶(C4H)、香豆酸辅酶A连接酶(4CL)活性上升,增加总酚、类黄酮和木质素含量来抑制杏果实接种发病率与病斑直径的上升。综上,EBR结合氯化钙处理可通过诱导苯丙烷代谢途径来增强杏果实对黑斑病的抗性。本研究结果可为减轻杏果实采后黑斑病提供技术参考与理论依据。     

24-表油菜素内酯对镉胁迫下大豆苗期生理特性的影响

为探讨外源EBR缓解大豆幼苗Cd毒害的机理,以大豆品种黑农48为试材,采用营养液水培法,以不同浓度(0.01、0.05、0.1、0.2、0.5mg·L-1)的24-表油菜素内酯(24-epibrassinolide,EBR)处理10mg·L-1Cd胁迫下的大豆幼苗,研究外源EBR对Cd胁迫下大豆幼苗株高及根系生长,过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)3种抗氧化酶活性,丙二醛(MDA)含量和叶绿素含量的影响。结果表明,Cd胁迫下,喷施0.01~0.1mg·L-1EBR对大豆各项生长指标的影响较单独Cd胁迫差异不显著;在0.2~0.5mg·L-1EBR范围内喷施0.5mg·L-1EBR明显提高大豆的株高、根长、地下鲜重、地下干重,较单独Cd胁迫分别提高了17.9%、9.5%、33.3%、38.1%。低浓度EBR(0.01mg·L-1和0.05mg·L-1)对3种抗氧化酶活性、叶绿素含量的提高作用及MDA含量的降低作用不显著;在0.1~0.5mg·L-1范围内喷施0.5mg·L-1EBR,Cd胁迫处理2d和8d后POD、CAT、APX活性及叶绿素含量较单独Cd处理升高42.6%和48.1%,20.2%和67.7%,97.3%和64.8%,29.7%和15.6%,MDA含量较单独Cd处理降低19.7%和27.8%。因此,0.1~0.5mg·L-1EBR是较适宜的喷施浓度,0.5mg·L-1EBR是最佳的喷施浓度。适宜浓度的外源EBR能促进Cd胁迫下大豆的生长,提高其抗氧化酶活性,减轻膜脂过氧化的程度和光合系统的损伤,有利于增强植株耐Cd胁迫能力。本研究为阐明EBR缓解Cd胁迫对大豆幼苗伤害的作用机理提供理论依据。     

外源24-表油菜素内酯对逆境胁迫下玉米种子萌发和幼苗生长的影响

为探讨不同胁迫对玉米种子生物化学特性的影响,采用不同浓度的24-表油菜素内酯(EBR)处理玉米种子,研究Na Cl和低温(15℃)胁迫下,外源EBR对玉米幼苗电解质外渗率(REC)、丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、脯氨酸、可溶性糖和各生长指标的影响。结果表明,在180 mmol·L~(-1)Na Cl胁迫下,0.050 mg·L~(-1)EBR可以显著缓解Na Cl的胁迫伤害,使玉米种子发芽率、发芽势、发芽指数、活力指数显著提高,盐害指数降低;幼苗株高、根长、植株鲜重、相对含水量、根冠比也显著提高;抗氧化酶(SOD、POD、CAT和APX)活性相应增加,脯氨酸和可溶性糖含量也相应提高,MDA含量和相对电导率降低。低温(15℃)胁迫下,与正常温度(25℃)相比,0.001~1.000 mg·L~(-1)范围内,EBR对提高玉米株高、根长、单株干鲜重、发芽率均有促进作用,0.100 mg·L~(-1)作用效果最好,对提高发芽势有一定促进作用,但无明显的规律性。由此可知,一定浓度的EBR浸种能缓解盐和低温对玉米的胁迫损伤,其作用机制可能是EBR可以激活细胞合成自由基清除酶的能力,且酶类物质通过相互协调作用减轻胁迫伤害。本研究为玉米的抗逆性研究提供一定的理论依据。     

品种和坐果对厚皮甜瓜光合特性及果实品质的影响

以2个网纹甜瓜品种和2个哈密瓜品种为材料,研究了叶片光合特性的品种间差异以及坐果对厚皮甜瓜叶片光合速率、果实质量及可溶性固形物含量的影响。结果表明,4个厚皮甜瓜品种的光合日变化均为双峰型曲线,第1个高峰在上午11：00点前后,第2个高峰在下午14：00前后,第2个峰值低于第1个高峰。授粉后,植株光合速率逐渐上升,至授粉...     

2,4-表油菜素内酯对NaCl胁迫下紫花苜蓿幼苗根系生长抑制及氧化损伤的缓解效应

为探讨外源2,4-表油菜素内酯(2,4-epibrassinolide,EBR)提高紫花苜蓿(Medicago sativa L.)耐盐性的生理调控机制,采用营养液水培法,以紫花苜蓿品种‘中苜3号’和‘陇中苜蓿’为材料,研究Na Cl胁迫下添加外源EBR对紫花苜蓿幼苗根系生长、渗透调节物质含量、抗氧化酶活性、非酶抗氧化物质、活性氧及MDA含量的影响。结果表明:150 mmol·L?1 Na Cl胁迫下,‘中苜3号’、‘陇中苜蓿’幼苗根系的生长显著受到抑制,根系干重和根系活力显著降低,幼苗根系中的可溶性蛋白含量和抗氧化酶活性显著降低,活性氧和MDA含量显著增加,根系脂质过氧化程度加剧,细胞质膜完整性受到破坏。添加0.1μmol·L?1外源EBR显著增加了2个品种苜蓿幼苗的主根长、根系总长度、根系总表面积、根体积、根尖数、根系干重和根系活力,幼苗根系中的可溶性蛋白含量、抗氧化酶(SOD、APX、GPX、CAT、GR)活性、非酶抗氧化物质(As A、GSH)含量均显著增加,超氧阴离子自由基(O2·?)产生速率、羟自由基(OH·)浓度、H2O2含量和膜脂过氧化产物MDA含量显著降低,有效缓解了根系脂质过氧化程度,提高了细胞质膜的完整性。说明外源EBR能够有效缓解Na Cl胁迫对紫花苜蓿幼苗根系生长的抑制作用,增强紫花苜蓿幼苗根系的渗透调节能力和抗氧化系统活性,降低活性氧的积累和膜脂过氧化水平,减小Na Cl胁迫对紫花苜蓿幼苗根系造成的氧化伤害,促进根系生长,增强苜蓿幼苗的抗盐性。     

表油菜素内酯对汞胁迫下小麦幼苗抗氧化系统的影响

为探讨表油菜素内酯(EBR)对小麦幼苗汞胁迫的调控作用,采用营养液水培法,研究汞胁迫下叶面喷施24-表油菜素内酯对小麦幼苗生长、叶片MDA及H2O2含量、质膜透性、抗氧化酶活性、抗氧化物质含量的影响。结果表明,50 mg·L-1汞处理小麦幼苗后,小麦幼苗的株高和干重显著降低,叶片的MDA、H2O2含量和质膜透性增加,SOD、POD和CAT活性下降,As A、GSH含量降低。与单独汞胁迫相比,叶面喷施一定浓度EBR促进了小麦幼苗的生长,降低了小麦幼苗叶片的MDA和H2O2含量,减小了质膜透性,提高了SOD、POD和CAT活性,增加了抗氧化物质As A、GSH含量,提高了As A/DHA、GSH/GSSG的比值,以EBR浓度0.01 mg·L-1为宜。综上,外源EBR可缓解汞胁迫对小麦幼苗的伤害,其机制可能与EBR能提高抗氧化酶活性及抗氧化物质含量、降低MDA和H2O2含量有关。本研究结果为降低汞污染土壤对作物生长的毒害作用提供了依据。     

表油菜素内酯对镉胁迫下番茄幼苗生长及镉累积的影响

采用盆栽试验研究不同浓度(0、0.02、0.1、0.5、2.5 mg/L)的表油菜素内酯(EBR)对镉胁迫下番茄幼苗生长及镉累积的影响。结果表明,镉处理后番茄幼苗的生物量、叶绿素含量、抗氧化酶(POD和CAT)活性均下降,丙二醛(MDA)含量、相对电导率和渗透调节物质含量均升高;喷施一定浓度的EBR(0.5 mg/L)后,番茄幼苗的生物量、叶绿素含量、抗氧化酶(POD和CAT)活性及脯氨酸含量均显著增加,可溶性蛋白、MDA含量和相对电导率有所下降,番茄幼苗根系和地上部分的镉含量分别上升了50.0%和93.4%,镉转运系数最低,为0.45。综上,喷施EBR能够增强番茄幼苗对镉胁迫的耐受性,促进幼苗生长,降低镉的转运系数,其中,EBR浓度为0.5 mg/L时效果最好。     

外源24-表油菜素内酯对低氧胁迫下黄瓜幼苗抗氧化系统及蛋白含量的影响

采用营养液水培,研究了根际低氧胁迫下外源24-表油菜素内酯(24-ep iBR)对2个抗低氧能力不同的黄瓜品种(“绿霸春四号”和“中农八号”)叶和根组织中抗氧化系统及根系中可溶性蛋白和热稳定蛋白含量的影响。结果表明,营养液添加1×10-3m g/L 24-ep iBR能显著提高黄瓜植株叶和根组织抗氧化酶SOD、POD活性,对CAT活性无明显影响,降低了O.2-和M DA含量,同时,根系可溶性蛋白和热稳定蛋白含量显著提高;与抗低氧性较弱的品种“中农八号”相比,24-ep iBR处理对抗低氧性强的品种“绿霸春四号”效果更明显,表明外源24-ep iBR处理通过促进抗氧化酶活性和蛋白含量的提高,降低低氧胁迫下植株体内RO S含量,增强植株低氧逆境的适应能力。     

不同变种甜瓜糖分积累及蔗糖代谢酶活性动态变化

为了解不同类型甜瓜糖分积累及糖代谢特点,选用厚皮甜瓜品种X228、普通甜瓜品种B154及越瓜品种H227为材料,定期取样测定果实成熟过程中的葡萄糖、果糖、蔗糖含量和蔗糖代谢相关酶活性,研究不同变种甜瓜果实发育过程中糖分积累及相关酶动态变化差异。结果表明,授粉15 d至果实成熟期间,3个甜瓜品种的果实葡萄糖与果糖含量的变化均较小,品种间差异不显著。3个甜瓜品种果实蔗糖含量存在显著性差异,其中H227果实几乎无蔗糖积累,葡萄糖和果糖是果实的主要糖组分;B154和X228果实蔗糖含量随着果实发育而快速增加,蔗糖积累存在明显的转折点,蔗糖是B154和X228这2个品种成熟果实中最主要的糖组分,且果实蔗糖含量提高的同时蔗糖磷酸合成酶(SPS)活性上升、酸性转化酶(AI)活性降低,蔗糖合成酶(SS)合成方向的活性与蔗糖含量关系不显著。根据蔗糖含量的差异,可将甜瓜分为蔗糖积累型和低蔗糖积累型两类,前者果实蔗糖含量的上升被认为是SPS活性上升与转化酶(特别是AI)活性下降共同作用的结果,后者果实内极低的蔗糖含量被认为是SPS活性较低导致的。本研究结果为甜瓜种质资源创新利用和甜瓜果实糖分积累调控研究奠定了理论基础。     

Effects of Irrigation and Nitrogen Rates on Growth,Yield, and Quality of Muskmelon in Semiarid Regions

Abstract

Muskmelon (Cucumis melo L. cv. ‘Polidor’) were grown under field conditions to investigate the effects of different nitrogen (N) levels (0, 40, 80, and 120 kg ha^{? 1}) on plant growth, water use efficiency, fruit yield and quality (weight, sizes, and water-soluble dry matter), leaf relative water content, and macro nutrition under three different irrigation regimes. Irrigation was applied based on cumulative class A pan evaporation (Ep). Plant treatments were as follows: (1) well-watered treatment (C) received 100% replenishment of Ep on a daily basis, (2) water-stressed treatment (WS) received 75% replenishment of Ep at three-day intervals, and (3) severely water-stressed (SWS): treatment received 50% replenishment of Ep at six- day intervals. Plants grown under C at 120 kg N ha^{? 1} produced significantly higher biomass (175.6 g plant^{? 1}), fruit yield (36.05 t ha^{? 1}), fruit weight (2.25 kg fruit^{? 1}), and leaf relative water content (93.5%) under increasing N levels than did the two deficit irrigation treatments. The WS or SWS treatments caused reductions in all parameters measured except water-soluble dry matter (SDM) concentrations in fruits compared with those receiving unstressed (C) treatment. The WS irrigation regime with 80 kg ha^{? 1} N significantly improved the fruit yield and size, plant dry matter, leaf area, and IWUE compared with the SWS regime. Increased N significantly enhanced foliar N in the unstressed plants. Increasing N rate in the SWS treatment did not increase fruit yield with the same trend found in the WS and C treatments with increasing N levels. The yield reduction under severe water shortage was much more severe at high N rates. Water use (ET) at the C treatment at 120 kg ha^{? 1} N ranged between 160 and 165 cm, while SWS reduced ET to 90 cm at 0 and 40 kg ha^{? 1} N. Nitrogen supply modified water use at C and WS irrigation regimes. Muskmelon yield response to N rate was quadratic and differed with the level of irrigation. This moderate water deficit (SW) may be an alternative irrigation choice with a suitable N application rate for muskmelon growers in arid and semi-arid regions if the goal is to irrigate an agricultural area with limited water supply for more growers, but not if it is maximizing economic yield. Growers should accept a significant yield reduction in exchange for water conservation.     

Effects of Silicon on Photosynthesis of Young Cucumber Seedlings Under Osmotic Stress

Effects of silicon (Si) application on photosynthesis of solution-cultured cucumber seedlings were investigated under osmotic stress and unstressed conditions. In unstressed conditions, silicon application had no effect on growth and photosynthetic parameters. The responses of the photosynthetic parameters to abruptly imposed osmotic stress did not differ between silicon treatments. After 1 week exposure to osmotic stress, growth reduction was observed, but it was less severe in seedlings grown with silicon than in those without silicon. Although there were no differences between silicon treatments in stomatal conductance, transpiration rate, cuticular transpiration, or xylem sap exudation rate under osmotic stress, leaf intercellular carbon dioxide (CO₂) concentration was significantly lower and photosynthetic rate tended to be higher in seedlings supplied with silicon. These results suggested that the silicon-induced alleviation of growth reduction under osmotic stress in cucumber was due to amelioration of stress-induced damage of leaf tissues rather than to improvement of leaf water status.     

水肥耦合对树莓光合特性和果实品质的影响

通过在田间利用防雨棚和测坑设施进行试验,研究水肥耦合对树莓光合特性及果实品质的影响。结果表明:土壤水分适度时适量增施肥料有利于树莓叶片净光合速率(Pn)提高,控制肥料施入可有效降低树莓叶片的蒸腾速率(Tr)和提高细胞间隙CO2浓度(Ci);肥料适度时适量提高土壤水分有利于提高树莓叶片的净光合速率(Pn)和叶片气孔导度(Gs),控制土壤含水量有利于树莓叶片的蒸腾速率(Tr)降低和细胞间隙CO2浓度(Ci)的提高。在施肥水平相同的条件下,适中的土壤含水量有利于果实中有机酸、可溶性糖和SOD营养物质的积累,充足的土壤含水量有利于果实中可溶性固形物和Vc含量的积累。土壤含水量控制在32%以上,施肥量在460.95kg/hm2水平有利于树莓光合速率(Pn)、气孔导度(Gs)的提高和午休时间的缩短;土壤含水量控制在26.2%以上,施肥量在270kg/hm2水平有利于降低树莓的蒸腾速率(Tr)和提高树莓果实品质。     

不同土壤水分下限对大棚滴灌甜瓜产量和品质的影响

以厚皮甜瓜品种伊莉莎白为材料,研究大棚滴灌条件下营养生长期不同土壤水分下限(75%田间持水量,I75;65%田间持水量,I65;55%田间持水量,I55;45%田间持水量,I45)对甜瓜生长、产量、品质以及灌溉水分利用效率的影响,并以沟灌(G75)作为对照。结果表明,株高、茎粗、叶面积和地上部干重均随着营养生长期土壤水分下限的降低而减小。I75果实横径、皮厚和肉厚均最大,果形指数最小;I65果实纵径最大。果实品质方面,总可溶性固形物(TSS)含量为:I65>I55>I75>I45;可溶性糖含量为:I55>I65>I45>I75;维生素C(Vc)含量为:I55>I65>I75>I45;可溶性蛋白质含量为:I55>I65>I45>I75;游离氨基酸总量为:I45>I65>I55>I75。I75的产量和平均单果重最高;I65的灌溉水分利用效率最高,达到29.16kg/m3,相比沟灌对照提高76.4%,可节水58.1%,而平均单果重仅比对照下降3.2%。综合考虑产量和品质,可以选择65%田间持水量作为武汉地区厚皮甜瓜营养生长期适宜的土壤水分下限指标。     

Physiological,nutritional and growth responses of melon (Cucumis melo L.) to a gradual salinity built-up in recirculating nutrient solution

Minimizing salinity impacts on yield in melon crops cultivated in closed-loop hydroponic systems requires better understanding of the physiological impact of gradual salt accumulation in the recycled solution. To attain this objective, different sodium chloride (NaCl) concentrations in the irrigation water, i.e. 0.7, 2.5, and 5 mM, were applied in two cropping seasons (winter-spring;WS and spring-summer;SS). In both seasons plant biomass and yield were negatively affected only in high NaCl-treated plants, due to stomatal limitations, which restricted carbon dioxide (CO₂) diffusion into the leaf, osmotic and salt-specific effects. However, a progressive NaCl built-up to maximum concentrations in the root zone solution of 15 (WS) and 20 mM (SS), enabled plants to preserve several physiological mechanisms, thereby adjusting growth and yield without impairing fruit quality. Our results suggest that the use of irrigation water, containing up to 2.5 mM NaCl, is feasible in melon crops grown in closed-loop hydroponic systems, without yield and quality losses.     

不同氮素形态配比对网纹甜瓜干物质分配和氮代谢的影响

该文研究了4种氮素形态配比(NO^-₃-N∶NH⁺₄-N分别为100∶0，75∶25，50∶50和25∶75)对基质栽培网纹甜瓜(品种为“春丽”和“蜜玲珑”)干物质积累和氮代谢的影响。结果表明,不同氮素形态配比影响了植株各器官干重占全株干重的百分比。随氮素形态中氨态氮比例的增加，叶片中硝酸还原酶、硝酸盐含量和可溶性蛋白质含量逐渐降低，而游离氨基酸含量则在NO^-₃-N∶NH⁺₄-N为50∶50的处理中最高。     

Effects of Antitranspirant Spray and Potassium: Calcium: Magnesium Ratio on Photosynthesis,Nutrient and Water Uptake,Growth, and Yield of Sweet Pepper

Sweet pepper plants (Capsicum annuum L.) were cultivated hydroponically under different nutrient cation ratios at both high potassium (K)/calcium (Ca) (12:2) or magnesium (Mg)/Ca (4:2) ratios, compared with half strength Hoagland's solution (K:Ca:Mg; 3.5:2:0.5). Additionally, antitranspirant (Pinolene) was sprayed every fortnight to the aerial part of the plant at 1% (v/v). The antitranspirant (AT) did not affect dry weight accumulation in the leaves, stems, roots, total plant leaf area, or leaf dry weight percentage. Net carbon dioxide (CO₂) assimilation was not impaired by the AT but the water uptake was reduced significantly independent of the nutrient solution used. The AT did not affect the cation uptake but high Mg significantly reduced Ca concentration in leaves, stems, and fruits, whilst high K had an effect only in old leaves and fruits. The AT reduced fructose and glucose concentration in the leaves but no effect was found in the fruits. Fruit yield was not affected by AT, but it was increased when plants were grown with high Mg/Ca. The percentage of blossom-end rot was reduced with the AT, whilst it was increased with the solutions having high K/Ca or high Mg/Ca. The AT significantly reduced fruit firmness in high Mg/Ca and control solution but no effect was found for fruit color, shape index, total soluble solids, or pericarp thickness.