Impact of Three Isolates of Cercosporidium personatum (Berk. Et M.A Curt.), a Pathogen of Late Leaf Spot, on Defoliation and Yield in Groundnut (Arachis hypogaea L.) under Controlled Conditions

Late leaf spot caused by Cercosporidium personatum is one of the most widespread groundnut leaf diseases. Along with early leaf spot and rust, it is one of the main fungal diseases hampering groundnut production worldwide. Late leaf spot accounts for significant yield losses throughout the world where groundnuts are grown. This reduction in yield caused by the disease could result in yield losses of between 50% and 70%. In Burkina Faso, the disease is present throughout the country, with incidence varying according to region and season. Could the variability in the incidence of the disease be linked to the nature of the isolates or to the conditions from each agro-ecological zone? In this study, the aim was to assess the capacity of three isolates from three agroclimatic zones of the country to defoliate and reduce groundnut yield. To this end, three isolates of Cercosporidium personatum (Berk. Et M.A Curt.) were collected in these zones and evaluated on three contrasting groundnut varieties. A split-splot design was used for the experiment. Isolates were prepared from samples collected in farmers’ fields. After incubation in the laboratory, leaf spots showing good sporulation were scraped off with a scalpel after immersing the leaves in distilled water. Inoculations were carried out under controlled environment. After inoculation with the isolate, the percentage of defoliation and the reduction in yield of these varieties were then evaluated. Inoculation was carried out from the 30th day after sowing with Cercosporidium personatum spore suspensions at 105 spores/ml. The study showed that the percentage of defoliation (P = 0.0001) and the reduction in yield (P = 0.0001) were significant. The study revealed that, whatever the variety, isolate I3TF from the Upper Basins region in the South Sudanese zone caused the greatest defoliation and the greatest reduction in yield. The variety TS32-1, regardless of the isolate used for the treatment, recorded the best yield. The variety PC79-79, regardless of the isolate used for the treatment, recorded the lowest percentage of defoliation. The highest defoliation recorded under the effect of the isolates was of the order of 72.20%;the highest yield reduction was of the order of 87.20% compared with the water control.

Effects of Aerated Irrigation on Leaf Senescence at Late Growth Stage and Grain Yield of Rice

With the japonica inbred cultivar Xiushui 09, indica hybrid combinations Guodao 6 and Liangyoupeijiu as materials, field experiments were conducted in 2007 and 2008 to study the effects of aerated irrigation on leaf senescence at late growth stage and grain yield of rice. The dissolved oxygen concentration of aerated water evidently increased and decreased at a slow rate. The soil oxidation-reduction potential under aerated irrigation treatment was significantly higher than that of the CK, contributing to significant increases in effective panicles, seed setting rate and grain yield. In addition, the aerated irrigation improved root function, increased superoxide dismutase activity and decreased malondialdehyde content in flag leaves at post-flowering, which delayed leaf senescence process, prolonged leaf functional activity and led to enhanced grain filling.

Slight shading after anthesis increases photosynthetic productivity and grain yield of winter wheat (Triticum aestivum L.) due to the delaying of leaf senescence

The solar radiation intensity and duration are continuously decreasing in the major wheat planting area of China. As a con- sequence, leaf senescence, photosynthesis, grain filling and thus wheat yield shall be affected by light deficiency. Therefore, two winter wheat （Triticum aestivum L.） cultivars, Tainong 18 （a large-spike cultivar） and Ji＇nan 17 （a multiple-spike cultivar）, were subjected to shading during anthesis and maturity under field condition in 2010-2011 and 2011-2012. Under the slight shading treatment （$1,88% of full sunshine）, leaf senescence was delayed, net photosynthesis rate （Po） and canopy apparent photosynthesis rate （CAP） were improved, and thus thousand-kernel weight （TKW） and grain yield were higher as compared with the control. However, mid and severe shading （S2 andS3, 67 and 35% of full sunshine, respectively） led to negative effects on these traits substantially. Moreover, superoxide dismutase （SOD）, peroxidase （POD） and cat- alase （CAT） activities in flag leaf were significantly greater under slight shading than those in other treatments, while the malondialdehyde （MDA） content was less than that under other treatments. In addition, the multiple-spike cultivar is more tolerant to shading than large-spike cultivar. In conclusion, slight shading after anthesis delayed leaf senescence, enhanced photosynthesis and grain filling, and thus resulted in higher grain yield.

Natural Variation of Leaf Thickness and Its Association to Yield Traits in indica Rice

Leaf thickness is an important morphological trait in rice. Its association to the yield potential, as of now has not been documented because of the shortage of the equipment which could conveniently measure the leaf thickness in rice. In this study, the thickness of top three leaves of 208 cultivars had been determined by a nondestructive rice leaf thickness instrument for the research of the natural variation of leaves thickness and its association to yield traits in indica rice. The results showed that the flag leaf was the thickest, and the 2nd leaf was thicker than the 3rd leaf. Analysis of variance indicated the existence of wide genetic diversity of leaf thickness among the investigated indica rice genotypes. The tight correlation among the thicknesses of the top three leaves means that the leaf thickness traits share one genetic control system. Leaf thickness had a significant positive correlation with leaf length and a positive correlation with leaf width, indicated that thicker leaf was beneficial to increasing the single leaf area. The results of correlation analysis revealed that thicker leaf should be profitable to the leaf erection, higher numbers of grains per panicle and higher grains weight per panicle. However, the significantly negative correlation between leaf thickness and number of panicles per plant counteracted the profitability from increased grains weight per panicle, so that the correlations of the thicknesses of the top three leaves to yield and biomass were positive but not significantly. It has made great progress in the genetic improvement of leaves thickness in inbred indica rice breeding in Guangdong Province, China, since the 1990s.

Effect of N fertilization rate on soil alkalihydrolyzable N, subtending leaf N concentration,fiber yield, and quality of cotton

Soil alkali-hydrolyzable nitrogen, which is sensitive to N fertilization rate, is one of the indicators of soil nitrogen supplying capacity. Two field experiments were conducted in Dongtai(120°19″ E, 32°52″ N), Jiangsu, China in 2009 and Dafeng(120°28″ E, 33°12″ N), Jiangsu province, China in 2010. Six nitrogen rates(0, 150, 300, 375, 450, and 600 kg ha^(-1)) were used to study the effect of N fertilization rate on soil alkali-hydrolyzable nitrogen content(SAHNC), subtending leaf nitrogen concentration(SLNC), yield, and fiber quality. In both Dongtai and Dafeng experiment station, the highest yield(1709 kg ha^(-1)), best quality(fiber length 30.6 mm, fiber strength 31.6 c N tex^(-1), micronaire 4.82), and highest N agronomic efficiency(2.03 kg kg^(-1)) were achieved at the nitrogen fertilization rate of 375 kg ha^(-1). The dynamics of SAHNC and SLNC could be simulated with a cubic and an exponential function,respectively. The changes in SAHNC were consistent with the changes in SLNC. Optimal average rate(0.276 mg day^(-1)) and duration(51.8 days) of SAHNC rapid decline were similar to the values obtained at the nitrogen rate of 375 kg ha^(-1)at which cotton showed highest fiber yield, quality, and N agronomic efficiency. Thus, the levels and strategies of nitrogen fertilization can affect SAHNC dynamics. The N fertilization rate that optimizes soil alkali-hydrolyzable nitrogen content would optimize the subtending leaf nitrogen concentration and thereby increase the yield and quality of the cotton fiber.

Nitrogen Nutrition Index and Its Relationship with N Use Efficiency, Tuber Yield, Radiation Use Effi ciency, and Leaf Parameters in Potatoes

Knowledge about crop growth processes in relation to N limitation is necessary to optimize N management in farming system. Plant-based diagnostic method, for instance nitrogen nutrition index （NNI） were used to determine the crop nitrogen status. This study determines the relationship of NNI with agronomic nitrogen use efficiency （AEN）, tuber yield, radiation use efficiency （RUE） and leaf parameters including leaf area index （LAI）, areal leaf N content （NJ and leaf N concentration （N0. Potatoes were grown in field at three N levels： no N （N 1）, 150 kg N ha^-1 （N2）, 300 kg N ha^-1 （N3）. N deficiency was quantified by NNI and RUE was generally calculated by estimating of the light absorbance on leaf area. NNI was used to evaluate the N effect on tuber yield, RUE, LAI, NAL, and NL. The results showed that NNI was negatively correlated with AEN, N deficiencies （NNI〈 1） which occurred for N 1 and N2 significantly reduced LAI, NL and tuber yield; whereas the N deficiencies had a relative small effect on NAL and RUE. To remove any effect other than N on these parameters, the actual ratio to maximum values were calculated for each developmental linear relationships were obtained between NNI and tuber RUE to NNI. stage of potatoes. When the NNI ranged from 0.4 to 1, positive yield, LAI, NL, while a nonlinear regression fitted the response of

Evaluation of Tomato Lines against Septoria Leaf Spot under Field Conditions and Its Effect on Fruit Yield

Field studies were conducted at Hazara Agriculture Research Station, Abbottabad to evaluate thirteen AVRDC lines along with one commercial check (Roma) for potential of fruit yield against septoria leaf spot during summer season 2014. The disease established itself by natural infection and disease severity was estimated with the help of 0 - 5 disease rating scale after 15 days interval from the onset of symptoms. The lines showed significant difference in % septoria leaf spot infection. The disease severity % increased up to 100% in line AVTO1314 whereas the lowest % severity was recorded in AVTO1173 which showed the highest yield (468.1 g) with average fruit weight 122.22 g while the significantly lowest mean yield/plant (35.05 g) was calculated in line AVTO1314 with fruit weight 47.92 g. It was concluded that the line AVTO1173 could be useful in genetic programs for incorporating resistant genes in local tomato germplasm against septoria leaf spot disease.

Low Co-Cultivation Temperature at 20°C Resulted in the Reproducible Maximum Increase in Both the Fresh Weight Yield and Stable Expression of GUS Activity after <i>Agrobacterium tumefaciens</i>-Mediated Transformation of Tobacco Leaf Disks

The importance of controlled temperature during the four-days co-cultivation period was evaluated under the most physiologically relevant conditions for Agrobacterium tumefaciens-mediated transformation of tobacco (Nicotiana tabacum L. cv. Xanthi (nn, Smith)) leaf disks. We compared the effect of temperatures ranging from 15°C, 18°C, 20°C, 22°C to 25°C on the stable expression of β-glucuronidase (GUS) activity of 14 days old hygromycin-selected leaf disks, and on the increase in the fresh weight yield of 28 days old kanamycin-selected calli. The highest average of GUS activity was obtained at 20°C among the five temperatures tested although the difference between the 18°C and 20°C treatment was not statistically significant. The GUS activity at 15°C was statistically lower than those at 18°C and 20°C. The GUS activity in 22°C treatment was an intermediate between the highest (18/20°C) and second highest averages (15°C), and was not statistically significantly different. The lowest average of GUS activity was observed at 25°C. The highest increase in the plate average of fresh weight yield was obtained at 20°C among the five temperature tested. The 20°C treatment was statistically significantly better than the 15°C and 18°C treatments. The 20°C co-cultivation treatment resulted in the higher FW yield than 22°C and 25°C even though the differences were not statistically significant. In conclusion, low co-cultivation temperature at 20°C resulted in the reproducible maximum increase in both the fresh weight yield and stable expression of GUS activity after transformation of tobacco leaf disks.

不同苜蓿品种叶片特征、光合生理特性与产量性状的比较

以国内外引进的8个紫花苜蓿(Medicago sativa L.)品种为试验材料,对比研究不同品种的叶片特征、产量性状和光合生理特性,采用相关性分析和通径分析法,探讨其与产量的关联性,以期为高产紫花苜蓿种质的筛选提供依据。结果表明:供试紫花苜蓿品种单株干重的变幅为0.88~1.21 g;各性状与单株干重的相关性按大小排序依次为:单株叶干重>比叶重>蒸腾速率>单株叶片数>叶形指数,单株叶干重是最突出的叶片特征指标。对单株干重的影响程度从大到小依次为:比叶重>气孔导度>可溶性蛋白>株高>蔗糖>可溶性糖>叶绿素总量,其中,比叶重是单株干重的主要决定因子。综上,高产紫花苜蓿种质筛选的重要指标包括:单株叶干重和比叶重,8个紫花苜蓿品种中‘甘农9号’、‘WL319HQ’和‘SG501’的单株干重、单株叶干重和比叶重均较大,可作为高产种质在育种工作中加以研究利用。

Study on the Relationship of Seedling Density and Line Spacing to Leaf-stem Ratio, DW/FW Ratio and Grass Yield of Forage Sweet Sorghum

[ Objectives ] The aim was to optimize the configuration of seedling density and line spacing of forage sweet sorghum （ Sorghum blcolor （ L. ） Moench） and explore its high-yield cultivation techniques. [ Methods] Effects of such two influencing factors as line spacing and seedling density on the leaf-stem ratio, DW/FW ratio and grass yield of forage sweet sorghum were analyzed by using split-plot experiment design experiment method and LSD method of IBM. SPSS. Statis- tics. v22 stati, stics software. [ Results ~ Seedling density and line spacing had no obvious effect on the leaf-stem ratio and DW/FW ratio of forage sweet sorghum but had obvious influences on the grass yield. Moreover, the optimal combination of seedling density and line spacing for high yield of forage sweet sorghum was A2 B4, that is, seedling density was 225 000 plants/hm2, and line spacing was 40 cm. [ Conclusions] The results provided a theoretical basis and technical support for high-yield cultivation techniques of forage sweet sorghum.

剑麻专用肥对石漠化山区剑麻生长及产量的影响

石漠化山区自然条件恶劣,剑麻具备耐瘠薄、耐旱、综合利用价值高、发展前景广阔等特点,成为石漠化山区产业扶贫的较好选择。试验结果表明,剑麻新增叶片数、叶长和鲜叶产量随专用肥施入量增加而增加,每株剑麻施用专用肥量为200 g时,鲜叶产量、经济效益最高。该结论为石漠化山区剑麻高产栽培技术提供技术参考。

栽培密度和收获期对工业大麻“云麻7号”主要农艺性状及花叶产量的影响

为了探明花叶用工业大麻在云南地区种植的最佳栽培密度和收获期,以云南主栽的工业大麻品种“云麻7号”为材料,分别于2019、2020年在云南省曲靖市沾益区进行大田随机区组试验。两年均设置4个栽培密度(0.5、1、2、3万株/hm^(2))和4个收获期(140、150、160、170 d),在收获期测定株高、茎粗、花叶产量、茎秆产量以及CBD含量等指标。于170 d收获时,两年的株高均在密度2万株/hm^(2)下达到最大值,分别为346.8 cm和267.1 cm,两年的茎粗均在密度0.5万株/hm^(2)下达到最大值,分别为44.3 mm和49.3 mm。2019年在140 d收获和3万株/hm^(2)密度条件下,花叶产量达到最大值3375 kg/hm^(2),2020年在170 d收获和2万株/hm^(2)密度条件下,花叶产量达到最大值5426 kg/hm^(2)。2019年在150 d收获和3万株/hm^(2)密度条件下,茎秆产量和地上部总产量均达到最大值,分别为7560 kg/hm^(2)和11014 kg/hm^(2),2020年在170 d收获2万株/hm^(2)密度条件下,茎秆产量达到最大值5632 kg/hm^(2),在170 d收获和3万株/hm^(2)密度下,地上部总产量达到最大值11001 kg/hm^(2)。大麻CBD含量两年均在160 d收获和1万株/hm^(2)密度条件下达到最大值,分别为1.2%和2.4%。栽培密度与收获期能影响工业大麻的花叶产量和CBD含量,栽培密度为3万株/hm^(2)和170 d时收获是“云麻7号”获得高产的重要栽培措施,同时在160 d收获和1万株/hm^(2)密度下栽培是获得高CBD含量的关键因素。

高光效小麦群体提高氮素吸收利用和产量的机理

[目的]研究通过调整小麦种植密度构建高光能利用效率群体,促进群体氮素积累、分配和转运的效果和机理,为充分利用光能提高小麦产量提供理论依据。[方法]试验于2018—2019年在安徽省濉溪县和蒙城县进行,以分蘖能力强(安1302)和弱(皖垦麦0622)的品种为材料,设置180×10^(4)株/hm^(2) (D1)、240×10^(4)株/hm^(2)(D2)、300×10^(4)株/hm^(2)(D3)、360×10^(4)株/hm^(2) (D4)4个种植密度,调查了群体籽粒产量、光合有效辐射截获率和截获量、光合有效辐射转化率,以此为基础,将小麦群体分为光效率高、中、低3个类型,比较了不同光效率类型群体的叶面积指数、花前氮素积累和转运量、花后(乳熟期)氮素积累量。[结果]品种、密度及其互作效应显著影响小麦群体的光能利用率和籽粒产量。高光效型群体的光能利用率和籽粒产量分别达1.4%和9.7 t/hm^(2),分别比中、低效型群体提高5%、14%和1%、5%。不同群体间开花期、乳熟期光合有效辐射截获率、开花期至乳熟期光合有效辐射截获量差异不显著,高光效型群体开花期至乳熟期光合有效辐射转化率高于中、低效型群体,达2.34 g/MJ。高光效型群体开花期、乳熟期叶面积指数及开花期茎秆叶鞘、叶片、单位叶面积氮素积累量均不同程度高于其他类型群体,分别达7.24、4.53及63.9 kg/hm^(2)、79.5 kg/hm^(2)和143.78μg/cm^(2)。此外,高光效型群体中群体和单茎花前氮素转运量分别为129 kg/hm^(2)和15 mg,均显著高于中、低效型群体,主要为茎秆+叶鞘和叶片氮素转运量较高,各营养器官间氮素转运率差异不显著,且高光效型群体成熟期个体营养器官仍保持较高的氮素积累量。[结论]高光效型群体开花期茎秆+叶鞘、叶片以及单位叶面积氮素积累量高,提高了开花期的叶面积指数,有利于光能的吸收和利用。虽然高光效型群体茎秆+叶鞘和叶片中的氮素转运量较高,其花后营养器官的氮素积累量依然较高,有助于维持花后较大叶面积指数,有效提升花后光合有效辐射转化率,获得更高的小麦籽粒产量。

氮肥后移对高温胁迫下春小麦旗叶生理特性和产量的影响

[目的]探究氮肥后移对高温胁迫下春小麦(Triticum aestivum L.)旗叶膜脂过氧化作用、抗氧化酶活性、渗透调节物质含量和产量的影响,筛选缓解春小麦花后高温早衰的科学施肥方法。[方法]2022年3月至2023年9月,以宁3015为试验材料,在宁夏农垦平吉堡农六队试验基地进行试验。采用裂区试验设计,主区为温度,设(25±2)℃(常温RT)和(35±2)℃(高温HT),副区为氮肥运筹。施氮总量一定(300 kg·N·km^(-2)),2022年设G1(分蘖期30%)、G2(拔节期30%)、G3(孕穗期30%)、G4(抽穗期20%)和G5(灌浆期20%)共5种施肥方式,2023年由前一年试验结果筛选出G1(分蘖期30%)、G3(孕穗期30%)和G5(灌浆期20%)共3个处理。于开花期开始取样,每5天取样一次,测定旗叶膜脂过氧化作用、抗氧化酶活性和渗透调节物质等指标。[结果]连续两年氮肥运筹试验中旗叶的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性、脯氨酸(Pro)含量和产量均在G5处理达到最高,丙二醛(MDA)和膜透性均在G5处理下最低,且与G1处理存在显著性差异(P<0.01)。根据皮尔逊(Pearson)相关性分析可知,春小麦籽粒产量和SOD、POD、CAT活性和脯氨酸含量显著正相关(P<0.05),与MDA含量和膜透性显著负相关(P<0.05)。综合评价表明,2022和2023年氮肥运筹的主成分得分排序为G5>G3>G4>G2>G1和G5>G3>G1,两年试验结果趋势一致。[结论]适当的氮肥后移可以降低高温胁迫下春小麦旗叶膜脂过氧化作用,增加抗氧化酶活性和渗透调节物质含量,进而增加产量,本试验中灌浆期施氮总量20%的处理较为适宜。

适时一次灌溉对8个冬小麦品种产量和生理特性的影响

为了探讨适时一次灌溉的灌溉效果和增产机制,以黄淮海麦区主推的8个小麦品种为材料,在大田和池栽条件下,设置适时一次灌溉和无灌溉(自然降雨)2种处理,测定抽穗期、灌浆前期、灌浆中期、灌浆后期旗叶生理指标和成熟期籽粒产量,研究适时一次灌溉对冬小麦产量和旗叶生理特性的影响。结果表明,适时一次灌溉改善了4个生育时期的旗叶生理特性。大田、池栽条件下适时一次灌溉处理旗叶超氧化物歧化酶(SOD)活性分别较无灌溉处理增加23.63%~39.07%、27.82%~54.53%,过氧化物酶(POD)活性增加16.39%~53.76%、16.93%~38.62%,过氧化氢酶(CAT)活性增加33.74%~51.59%、26.13%~45.06%,可溶性糖含量增加27.73%~46.34%、24.75%~37.31%,脯氨酸含量增加26.29%~37.84%、21.41%~41.33%,可溶性蛋白含量增加16.56%~42.06%、14.85%~31.69%,净光合速率增加11.51%~47.25%、24.36%~43.33%,丙二醛(MDA)含量下降12.32%~18.64%、14.85%~22.79%,小麦籽粒产量平均增加17.95%和29.27%。适时一次灌溉条件下,不同品种间比较,以周麦32和周麦36较无灌溉增产幅度较大,分别为31.50%和28.23%,可作为丰产抗旱性品种在有限灌溉旱作区进行推广。本研究结果为冬小麦适时一次灌溉研究及品种优化布局提供了参考。

海拔对大别山区野生宽叶山蒿叶片性状和品质的影响

目的:探究海拔对大别山区野生宽叶山蒿叶片性状和品质的影响。方法:对宽叶山蒿的叶片性状、出绒率、叶绒燃烧热解质量和叶片成分含量进行测定,利用相关性分析筛选与海拔有关联的指标,并通过主成分分析对不同海拔叶片成分进行综合评价。结果:随着海拔升高,宽叶山蒿叶长和叶宽呈先减小后增加的趋势,出绒率呈逐渐升高的趋势;除海拔1720 m宽叶山蒿叶绒的综合燃烧特性较差、燃烧放热量较少外,各海拔叶绒的点燃性能、燃烧后的速度和稳定性、燃烧持久性、燃尽性能和燃烧过程的放热量均相似。叶片成分比较发现,海拔≤1084 m,桉油精、α-古巴烯、石竹烯和氧化石竹烯相对含量较高;海拔≥1550 m,乙酸龙脑酯、大根香叶烯D相对含量较高;海拔≥1084 m,绿原酸、隐绿原酸、异绿原酸C质量分数较高。相关性分析发现,宽叶山蒿叶片性状与海拔不相关,出绒率、大根香叶烯D相对含量、绿原酸质量分数、隐绿原酸质量分数与海拔呈正相关(P<0.01),异绿原酸C质量分数与海拔呈正相关(P<0.05),氧化石竹烯相对含量与海拔呈负相关(P<0.01)。主成分分析显示,高海拔宽叶山蒿叶片成分综合得分较高。结论:不同海拔造成的环境差异可能是导致野生宽叶山蒿叶片性状、出绒率、叶绒燃烧热解质量和叶片成分差异的重要因素,高海拔更利于野生宽叶山蒿的生长。

免耕对玉米生产力的影响:基于全球荟萃分析

通过对196篇相关文献的1 043对数据进行全球荟萃分析,评估免耕条件下玉米籽粒产量、秸秆生物量和叶面积指数的变化,并探讨气候、土壤、管理因素对其影响程度和方向。结果表明,相较于传统翻耕,免耕总体上显著降低了玉米籽粒产量、秸秆产量和叶面积指数5.7%、4.1%和9.7%。然而,这种效应因气候、土壤和管理措施而不同。在相对干旱的气候环境(年平均气温为>15℃、年平均降雨<600 mm)和恶劣的土壤条件(土壤体积质量>1.4 g/cm3、土壤有机碳含量<5.8 g/kg、土壤全氮为<0.75 g/kg)下,免耕条件下玉米生产力(籽粒产量和秸秆生物量)水平相对更好。其中,土壤有机碳含量和土壤速效钾含量与玉米籽粒产量呈显著负相关,年平均降雨和土壤速效磷含量与玉米籽粒产量和秸秆生物量呈显著负相关,土壤体积质量与玉米籽粒产量和秸秆生物量呈显著正相关。此外,肥料的高效施用、多样化的种植模式(间作或轮作)、秸秆还田等管理措施能抵消免耕条件下玉米生产力的负效应。总体而言,气候土壤环境相对更恶劣的区域可以从免耕技术上获益更多,而合理的田间管理措施也可以为免耕技术提供更好的生产力效应。

遮荫对盐胁迫下油葵生长和光合生理的影响

盐碱地光伏系统下作物生长受到盐分和遮荫的双重影响,研究双重逆境下作物的生理响应对该系统内作物种植有重要指导意义。本研究以油葵(Helianthus annuus L.)为试验材料,采用盆栽试验,设3个盐分水平(在初始含盐量的基础上外加NaCl含量0 g·kg^(−1)、3 g·kg^(−1)和5 g·kg^(−1))和4个遮荫水平(0%、30%、60%和90%),探究遮荫对盐胁迫下油葵生长、光合特性、叶片解剖结构、生物量积累和分配及籽粒产量等的影响,为盐碱地光伏系统下开展作物种植提供理论依据。结果表明,不同盐分水平下,与不遮荫(遮荫水平0%)处理相比,遮荫会破坏油葵叶片光合反应中心,降低光能转换效率,减小叶片厚度和栅栏组织层,减少光合产物积累,进而抑制茎粗和花盘的生长,影响光合产物分配方向,最终降低籽粒产量;但适度遮荫下油葵会通过增加株高、增大叶面积、提高核酮糖-1,5-二磷酸羧化酶(Rubisco酶)和磷酸烯醇式丙酮酸羧化酶(PEPC酶)活性等方式提高叶片的光捕获能力,促进光合作用进行。不同遮荫水平下,与无盐分处理相比,轻(3 g·kg^(−1)NaCl)、重(5 g·kg^(−1)NaCl)度盐胁迫均会降低油葵的光合效率,抑制株高、茎粗、花盘和叶片的生长,减少光合产物的积累,最终降低籽粒产量,且不同盐胁迫浓度下油葵生长和光合生理特性在不同遮荫水平的变化规律不一致。其中,30%遮荫水平能显著提高轻度盐胁迫下油葵叶片的Rubisco酶和PEPC酶活性,减小叶片厚度,增大栅栏组织层,提高水分利用效率,进而提高油葵光合效率,促进油葵生长。研究表明弱光环境下油葵会通过改变自身形态、光合酶活性、光合产物分配等方式来应对环境胁迫,且遮荫能在一定程度上缓解盐胁迫对油葵造成的负面影响。其中,30%遮荫水平对缓解轻度盐胁迫引起的油葵光合能力降低和生长抑制的效果较好。