Enhancing the Salt Tolerance Potential of Watermelon (<i>Citrullus lanatus</i>) by Exogenous Application of Salicylic Acid

Salicylic acid (SA) is a vital plant growth regulator providing promising role in plant development and adopts defense mechanism to abiotic stresses. Salinity is the most limiting abiotic factor for plant development and growth changes in watermelon by producing reactive oxygen species and ultimately oxidative stress. The present study was aimed to investigate the mechanism involved in salt stress alleviation in watermelon (Citrullus lanatus Thanb. Mavs.) through the foliar application of salicylic acid. Watermelon cv. Charleston Gray was grown under moderate saline regime of 3 ds·m-1 NaCl and sprayed with salicylic acid with four level (0.5, 1.0, 2.5 and 5.0 mmol/L) compared along with control. SA @ 5.0 mmol/L was found to be very effective in mitigation of salt stress. SA was found to be very effective in alleviation of salinity stress by produced antioxidants and acted as osmo-regulator.

Lycopen’s Stability in Watermelon Juice (<i>Citrullus lanatus</i>) Regarding to Technological Routes

Highly prized by consumers, watermelon is rich in water, but also in micronutrients including lycopene, pigment responsible for the red color. It is also a powerful antioxidant which has many virtues including the prevention and treatment of certain diseases. The transformation into nectar of watermelons combined with treatment could cause several modifications including the alteration of coloring. It is in this context that this study focuses on the variation of the lycopene content in nectars. Thus, nectars of 12°Brix and 15°Brix were prepared from three varieties of watermelon (Sugar Baby, Crimson Sweet and Charleston Gray). To study the stability, two pasteurization scales (85°C/15min and 95°C/15min) and one sterilization scale (105°C/15min) were applied to the different nectars produced. The results obtained showed that the Sugar Baby variety is richer in lycopene (24.39 mg·kg-1) with a higher pH (5.80). In addition, the study showed, for the Sugar Baby variety, an increase of lycopene with the addition of sugar and the heat treatment (a maximum of 42.83 mg·kg-1 for SbF12T105). On the other hand, for the Crimson Sweet and Charleston varieties, the highest rate of lycopene, except the heat-treated ones, are those formulated at 12°B (10.46 mg·kg-1 for CrF12T105 and 18.40 mg·kg-1 for ChF12T105). Without any health consequences, the formulation combined with heat treatment would preserve the lycopene content of watermelon nectars.

Nutritive Values and Antioxidant Activity of <i>Citrullus lanatus</i>Fruit Extract

Citrullus lanatus (Watermelon) is a fruit cultivated and consumed in Africa for its essential nutrients which are very beneficial to the human body. The present study was designed to evaluate the nutritive contents, free radical scavenging activities and phytochemical components of C. lanatus fruit. The extract of the fruit was subjected to in vitro antioxidant assessment using 1,1-di-phenylpicryl-hydrazyl radical (DPPH) and hydrogen peroxide radical scavenging assays. The proximate and phytochemical analyses were conducted using standard procedures. The results of this study showed that C. lanatus fruit had very high moisture content and its crude protein, crude fat, crude fibre and ash content were all in traceable amounts. The sugar content was considerably high in comparison with other nutritive contents. Lycopene and β-carotene contents of C. lanatus fruit were estimated to be 4537.83 and 308.71 μg/100g respectively. The gross energy evaluation showed a value of 0.335 Kcal/g. The fruit extract exhibited significant (p 50 of 0.10 mg/ml) and hydrogen peroxide radicals scavenging activity (IC50 of 0.62 mg/ml) in comparison with the positive control butylated hydroxytoluene (BTH). This study therefore recommends that C. lanatus fruit could be an excellent source of antioxidants which may prevent diseases whose pathogenesis involves oxidative stress.

Characterization of Water Melon (<i>Citrullus lanatus</i>) Genotypes under High Salinity Regime

For horticultural crops and especially for vegetables, salinity is dilemma. It is the most limiting factor for plant growth and development by producing reactive oxygen species and ultimately oxidative stress. In the present study, the screening of watermelon (Citrullus lanatus Thanb. Mavs.) Cultivars was observed for salt tolerance. Four salinity levels (1.5, 3, 4.5, and 6 dS·m-1 NaCl) and six cultivars (Crimson, Charleston Gray, Anarkali, Chairman, Sugar Baby and Champion) tested for screening. It was observed that all morphological attributes and ionic contents were severely affected. But it was revealed by statistical analysis that Charleston Gray was affected least while Champion was most salt sensitive cultivar due to oxidative stress and ionic toxicity. It is concluded that different genotypes under consideration vary in their ability to tolerate salt stress.

西瓜ClPP2C3克隆及表达分析

【目的】蛋白磷酸酶2C(protein phosphatase 2C,PP2C)是动植物中均存在的一类蛋白磷酸酶,拟探究其在西瓜果实成熟过程中发挥的重要作用。【方法】通过逆转录PCR(reverse transcription-polymerase chain reaction,RT-PCR)从栽培类型西瓜‘97103’中克隆ClPP2C3,并对其进行生物信息学、表达模式和亚细胞定位分析。【结果】西瓜ClPP2C3的cDNA序列长度为1317 bp,编码438个氨基酸,其分子量大小为47.81 kD,蛋白质等电点为5.12。ClPP2C3包含1个PP2C保守结构域,与负调控果实成熟的番茄SlPP2C3、草莓FaABI1具有较高的同源性。西瓜ClPP2C3在细胞核表达。ClPP2C3在含糖量高的栽培品种中表达量显著高于含糖量低的野生品种。栽培品种ClPP2C3的2kb片段长度启动子活性显著高于野生品种,而1kb片段长度启动子活性之间无显著差异。【结论】由1-2kb区间SNP导致的启动子活性差异对不同含糖量品种ClPP2C3表达量存在影响。

噻虫胺种子处理对西瓜生长发育的影响及其残留分析

为明确新烟碱类杀虫剂噻虫胺种子处理对西瓜生长发育和品质的影响,以及在西瓜中的残留状况,本研究以10%噻虫胺种子处理悬浮剂为供试药剂,采用拌种试验,开展噻虫胺对西瓜生长发育的影响及残留分析研究。结果表明,噻虫胺有效成分用量100~250 g/100 kg范围内,对西瓜出苗安全;噻虫胺拌种处理对西瓜苗期的株高、茎粗、叶绿素含量和叶面积有一定的促进作用,随着西瓜的生长促进作用减弱,西瓜出苗后30 d,各处理间差异不显著;噻虫胺各处理西瓜产量均高于空白对照,对西瓜有一定的增产作用;噻虫胺拌种可不同程度地提高西瓜果实中可溶性糖、可溶性固形物含量,提升西瓜的品质;随着西瓜生长发育,叶片内噻虫胺含量逐渐降低,出苗后45 d,叶片内未检测到噻虫胺残留;西瓜收获时果实中未检测到噻虫胺残留,西瓜根部土壤中噻虫胺的残留量在0.0412~0.0975 mg/kg之间。综上所述,噻虫胺100~250 g/100 kg用量范围内处理西瓜种子,对西瓜苗期生长有一定促进作用,并可提高产量,改善西瓜的品质,叶片内噻虫胺含量随植株生长逐渐降低,果实中无残留,本研究为噻虫胺种子处理在西瓜生产实践中合理、安全、高效的应用提供技术支撑。

Suboptimal Temperature Acclimation Enhances Chilling Tolerance by Improving Photosynthetic Adaptability and Osmoregulation Ability in Watermelon

The temperature drop of plants from the optimal requirements can increase tolerance to severe chilling stress. Photosynthesis and osmoregulators were analyzed during chilling stress to explore the adaptation mechanisms that underlie the induction of chilling tolerance in response to suboptimal temperature. The relationships of these processes to suboptimal temperature acclimation in watermelon were then determined.Suboptimal temperature-acclimated watermelon plants demonstrated tolerance during chilling stress, as indicated by the decreased electrolyte leakage and malondialdehyde accumulation compared with those non-acclimated watermelon plants. Chilling-induced photoinhibition and reduction in CO2 assimilation rate were alleviated after suboptimal temperature acclimation. The xanthophyll cycle level was enhanced by improving thermal dissipation ability and avoiding light damage. Consequently, the chilling tolerance of suboptimal temperature-acclimated watermelon plants was enhanced. The osmoregulation ability induced by suboptimal temperature acclimation protected watermelon plants against chilling injury because of the accumulation of small molecular substances, such as soluble sugar and proline. The protein levels of Rubisco activase(ClRCA) and the gene expression of the Benson–Calvin cycle simultaneously increased in suboptimal temperature-acclimated watermelon plants during chilling stress. Chilling tolerance in watermelon plants induced by suboptimal temperature acclimation is associated with enhanced photosynthetic adaptability and osmoregulation ability.

Amination of biochar surface from watermelon peel for toxic chromium removal enhancement

Watermelon peel residues were used to produce a new biochar by dehydration method.The new biochar has undergone two methods of chemical modification and the effect of this chemical modification on its ability to adsorb Cr(VI)ions from aqueous solution has been investigated.Three biochars,Melon-B,Melon-BO-NH_(2) and Melon-BO-TETA,were made from watermelon peel via dehydration with 50%sulfuric acid to give Melon-B followed by oxidation with ozone and amination using ammonium hydroxide to give Melon-BO-NH_(2) or Triethylenetetramine(TETA)to give Melon-BO-TETA.The prepared biochars were characterized by BET,BJH,SEM,FT-IR,TGA,DSC and EDAX analyses.The highest removal percentage of Cr(VI)ions was 69%for Melon-B,98%for Melon-BO-NH_(2) and 99%for Melon-BO-TETA biochars of 100 mg·L^(−1) Cr(VI)ions initial concentration and 1.0 g·L^(−1) adsorbents dose.The unmodified biochar(Melon-B)and modified biochars(Melon-BO-NH_(2) and Melon-BO-TETA)had maximum adsorption capacities(Q_(m))of 72.46,123.46,and 333.33 mg·g^(−1),respectively.The amination of biochar reduced the pore size of modified biochar,whereas the surface area was enhanced.The obtained data of isotherm models were tested using different error function equations.The Freundlich,Tempkin and Langmuir isotherm models were best fitted to the experimental data of Melon-B,Melon-BO-NH_(2) and Melon-BO-TETA,respectively.The adsorption rate was primarily controlled by pseudo-second–order rate model.Conclusively,the functional groups interactions are important for adsorption mechanisms and expected to control the adsorption process.The adsorption for the Melon-B,Melon-BO-NH_(2) and Melon-BO-TETA could be explained for acid–base interaction and hydrogen bonding interaction.

Effect of Various Soil Media on Disease Severity of <i>Fusarium</i>Wilt in Watermelon

Fusarium wilt is a major disease of watermelon (Citrullus lanatus) caused by Fusarium oxysporum f. sp. niveum (Fon). Use of host resistance is the most effective management strategy for the disease, and a major objective for breeding programs. Screening assays rely on the ability to discriminate resistant and susceptible genotypes in segregating populations. However, complex interactions between Fon and the soil environment can influence symptom development and disease severity rating. In the current study, severity of Fusarium wilt (race 1) in sand-peat (1:1 v/v), sand-perlite (1:1), sand-peat-vermiculite (4:1:1), peat-perlite (1:1) and Fafard 3B potting media was compared among five watermelon cultivars: Calhoun Gray (resistant), SunSugar (resistant), Allsweet (moderately resistant), Sugar Baby (susceptible) and Charleston Gray (susceptible). Plant biomass (average dry weight/plant) was lowest in peat-perlite (1.67 g) and sand-peat (2.16 g), and was significantly different (α = 0.05) from that of sand-perlite (3.48 g), sand-peat-vermiculite (4.94 g) and Fafard 3B (6.90 g). Conversely, disease severity [area under disease progress curve (AUDPC)] across cultivars was significantly higher in peat-perlite (AUDPC = 62.96) and sand-peat (AUDPC = 40.87), than in sand-perlite (AUDPC = 11.55), sand-peat-vermiculite (AUDPC = 10.67) and Fafard 3B (AUDPC = 9.29). Consistent discrimination (α = 0.05) of resistant and susceptible cultivars was realized in sand-peat-vermiculite and Fafard 3B, but was not possible in peat-perlite, sand-peat and sand-perlite. Collectively, these findings support suitability of sand-peat-vermiculite and Fafard 3B for routine screening of Fusarium wilt resistance in watermelon.

镉胁迫对西瓜幼苗生长及其叶片解剖结构和生理特性的影响

该研究以‘北抗1号’西瓜幼苗为试验材料,采用实验室盆栽方法,考察在不同浓度镉胁迫(0、60、120、180和240 mg/L)处理下西瓜幼苗的生长及其叶片生理特性和解剖结构的变化特征,初步探讨西瓜耐受镉胁迫的生理机制。结果显示:(1)在镉胁迫条件下,西瓜幼苗的生长受到抑制,随着镉胁迫浓度的增加,西瓜幼苗的叶片形态黄化现象逐渐加重,根系形态逐渐纤弱,株高、茎粗、茎节数和叶片数均呈现下降趋势。(2)镉胁迫下,西瓜幼苗叶片主脉中细胞受损,主脉直径显著减小,叶肉组织疏密度显著降低。(3)随着镉胁迫浓度的升高,西瓜幼苗的含水量、净光合速率、SOD活性等显著降低,丙二醛和游离脯氨酸含量显著升高,POD活性和可溶性蛋白含量先升高后降低,生理特性受到显著影响。研究发现,‘北抗1号’西瓜幼苗对镉有一定的适应性,在低浓度(60 mg/L)镉胁迫处理下,西瓜幼苗的形态特征、生理特性变化不显著,但在高浓度(180 mg/L)镉胁迫下,幼苗的生长受到严重抑制,渗透调节系统以及生物膜保护系统严重受损。

麻地膜覆盖与灌水量对春秋季设施栽培西瓜产量和品质的影响

为了探究地膜覆盖和灌水量对设施栽培西瓜产量及品质的影响,试验在大棚滴灌栽培条件下设置两种地膜:黑色塑料地膜(F_(1))、白色麻地膜(F_(2)),3个水分处理:标准灌水量(W_(1))、2/3标准灌水量(W_(2))、1/2标准灌水量(W3),分别在西瓜伸蔓期、开花坐果期和膨瓜期进行处理。结果表明:不同地膜覆盖和灌水量对春季及秋季西瓜植株的主蔓长、主茎粗、果实单果重、中心及边缘可溶性固形物含量的影响均无明显规律。在春季,相同地膜覆盖条件下,开花坐果期西瓜的叶面积与灌水量呈正相关。不同地膜覆盖条件下,相同灌水量处理的秋季西瓜中心及边缘可溶性固形物含量表现为塑料地膜>麻地膜。综合分析:F_(2)W_(2)(白色麻地膜+2/3标准灌水量)可作为武汉地区春季西瓜的栽培模式;F_(1)W_(2)(黑色塑料地膜+2/3标准灌水量)、F_(2)W_(2)可作为武汉地区秋季西瓜的栽培模式。

武汉市设施西瓜种植土壤健康评价指标初步构建

对武汉市主要农业生产区设施西瓜[Citrullus lanatus(Thunb.)Matsum.&Nakai]土壤(0~20 cm)和农产品进行取样,并检测土壤理化指标和微生物数量及农产品品质指标。结果表明,研究区域内土壤酸碱度空间变异较大,pH在4.91~7.16;土壤有机质含量变化范围在9.43~30.75 g/kg;种植土壤的硝态氮含量非常丰富,有效磷和速效钾含量均处于较高水平;土壤容重和紧实度较为接近,土壤田间持水量因种植方式的不同存在一定差异;设施栽培土壤中真菌数量变化不大,而细菌和放线菌数量浮动较明显。通过主成分分析方法对武汉市设施西瓜土壤的健康评价指标进行筛选,初步选择了pH、速效钾含量、有机质含量、硝态氮含量、田间持水量和细菌含量等指标作为评价指标。

鄂州市土壤墒情变化规律与西瓜种植区土壤水分评价指标

为定量评估鄂州市西瓜(Citrullus lanatus L.)种植区土壤含水量和科学管控水分,利用鄂州市2015—2020年的气象资料及墒情监测数据,分析了鄂州市土壤墒情变化规律,初步建立西瓜土壤墒情评价指标体系,并选取日平均气温、7 d平均气温、日降水量、7 d累积降水量、相对湿度、平均风速和日照时数7个气象因子进行主成分分析。结果表明,鄂州市表层土壤墒情受降水量、平均气温、日照时数影响较大,平均风速对土壤水分变化影响不大;主成分分析预报模型能较好地预报土壤水分,达到乙级预报标准,可用于预报作业。采用该评价指标体系,西瓜种植区可以在生长周期内适当调整水分的供给,促进植株的生长,提高果实品质,还能节约有限的水资源。

不同砧木嫁接对露地西瓜品质的影响

西瓜嫁接栽培是克服西瓜重茬障碍、预防枯萎病实现高产稳产的一项有效措施,但生产上嫁接栽培经常出现西瓜果皮增厚、有异味、果肉较硬、品质下降等质量问题。以西安市长安区露地西瓜种植为例,对比分析了不同砧木嫁接对长安区主栽露地西瓜产量和品质的影响,筛选出适合该地土壤和气候特点的西瓜嫁接的理想砧木。

^(60)Co-γ射线辐射西瓜种子对叶片光合色素含量和气体交换参数的影响

以12个不同千粒重的西瓜(Citrullus lanatus)品种干种子为试验材料,设置6个^(60)Co-γ射线剂量辐射处理,研究不同辐射剂量对西瓜种子的影响,并通过大田试验观察辐射材料的性状表现(开花期及果实性状)。结果表明,西瓜种子经^(60)Co-γ射线辐射后,叶片中的叶绿素a、类胡萝卜素含量随着辐射剂量的增大总体呈先增加后减小的趋势,叶绿素b含量及气孔导度、净光合速率、蒸腾速率总体随着辐射剂量的增加而减少;^(60)Co-γ射线辐射对不同千粒重西瓜干种子的敏感性由强到弱依次为大种子、小种子、中等种子;不同基因型西瓜种子辐射敏感性由强到弱依次为杂交种子、常规种子。

双膜西瓜育苗及移栽的农业气象指标研究

为进一步提高西瓜的产量和质量,了解不同育苗温度下的最适移栽日期,细化西瓜适宜移栽期的农业气象指标,进行了西瓜育苗及移栽试验。结果显示:最早适宜移栽的日期为3月1日—3月9日,最安全的移栽的日期为3月10日—3月15日;移栽的气象指标为:棚内气温不低于-2.0℃,棚内膜下5 cm地温不低于5℃。

^(60)Co-γ射线辐射对西瓜蔓长、分枝数及开花期的影响

为了探索^(60)Co-γ射线辐射对西瓜[Citrullus lanatus(Thunb.)Matsum.&Nakai]开花期及果实性状的影响,选取千粒重不同的12个西瓜品种种子为材料,设置6个剂量辐射处理,研究不同辐射剂量对西瓜种子开花期及果实性状的影响。研究发现,西瓜蔓长对^(60)Co-γ射线辐射敏感,开花期对其不敏感。400 Gy条件下西瓜分枝数与对照差异达显著水平;800 Gy条件下对西瓜开花期抑制作用明显;西瓜种子适宜的^(60)Co-γ射线辐射剂量为400~600 Gy,不同千粒重西瓜种子的蔓长对^(60)Co-γ射线辐射的敏感性为大种子>小种子>中等种子,分枝数对^(60)Co-γ射线辐射的敏感性为小种子强于中等种子,开花期对^(60)Co-γ射线辐射的敏感性为大种子>小种子=中等种子。

西瓜抗枯萎病育种分子标记辅助选择的研究

将西瓜野生种质ＰＩ２９６３４１抗枯萎病生理小种１的抗性基因连锁的ＲＡＰＤ标记ＯＰＰ０１／７００进行克隆、测序，Ｓｏｕｔｈｅｒｎ杂交证明此标记为１个单拷贝，并转化为ＳＣＡＲ标记，简化了ＳＣＡＲ扩增产物的检测技术。上述技术在抗病转育后代选择中得到了很好的应用，初步建立了西瓜抗枯萎病育种分子标记辅助选择技术系统。

砂田西瓜不同粒径砂砾石覆盖的水分效应研究

为分析不同粒径砂砾石对砂田西瓜蒸散量和土壤蒸发的影响,2004年在位于黄土高原西北部的皋兰县境内进行了不同粒径砂砾石覆盖的水分效应研究,结果证明砂砾石粒径大小对砂田西瓜蒸散量和土壤蒸发有显著影响,粒径2～5mm覆盖处理的蒸散量显著低于粒径5～20mm和20～60mm处理,但与不覆砂的对照没有显著差异。粒径愈大,砂田土壤蒸发愈多,土壤蒸发在西瓜田总蒸散中占的比例愈高。覆砂能够有效减少土壤蒸发,未覆砂处理全生育期土壤蒸发耗水占西瓜蒸散的40.7%,而覆砂处理仅占总蒸散的17.8%～25%。西瓜田覆砂加覆膜,土壤蒸发比不覆盖田减少78～93.7mm,比仅覆砂不覆膜田减少16.9～26.3mm。不同粒径砂砾石处理之间的产量差异不显著,但水分生产率有显著差异,2～5mm粒径砂砾石覆盖处理的水分生产率显著高于20～60mm粒径处理。但砂砾石粒径减小,砂田西瓜的含糖量降低。研究结果还证明,西瓜田覆砂能有效地提高其产量,含糖量和水分生产率,适合砂田覆盖的砂砾石粒径以5～20mm为宜。

用重组自交系构建西瓜分子遗传图谱

用可溶性固形物含量高、皮薄、感枯萎病的栽培西瓜自交系 (Citrulluslanatusvar lanatus) 9710 3和可溶性固形物含量低、皮厚、抗病的野生西瓜种质 (Citrulluslanatusvar citroides)PI2 96 341杂交所得重组自交系F8的 117个单株为作图群体 ,构建西瓜分子遗传图谱。该图谱包含 87个RAPD标记、 13个ISSR标记和 4个SCAR标记 ,分为 15个连锁群 ,包括 1个最大的含 31个标记的连锁群 (2 77 5cM )、6个大的含 4 - 12个标记的连锁群 (5 1 7cM - 172 2cM )和 8个小的含 2 - 5个标记的连锁群 (7 9cM -46 4cM) ,覆盖基因组的 10 2 7 5cM。两个标记间的平均距离为 11 5 4cM。该图谱为以后获得饱和的分子遗传图谱。