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.

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.

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.

Anti-inflammatory and Analgesic Effects of Extract from Roots and Leaves of Citrullus lanatus

Objective To study anti-inflammatory and analgesic effects of extract from the roots and leaves of Citrullus lanatus and assess their acute toxicity in animals. Methods The mouse model with ear edema induced by xylene and the rat model with paw edema or granuloma by carrageenin or cotton pellet were used for anti-inflammatory effects of the extract. Effects of the extract on analgesia was tested respectively by measuring the latency of mice licking hind foot from hot plates and by counting the times of body twisting in response to acetic acid. The acute toxicity of the extract was determined with the method of Bliss. Results The extract significantly inhibited the ear edema, granuloma hyperplasia, and paw edema. It significantly lifted the pain threshold on mouse hot-plate responses and reduced their writhing times. During the 7 d observation period in its acute toxicity assay, no apparent toxic reaction was shown and all mice survived at a dose of 87 g extract per kg body weight. Conclusion The extract could protecte mice/rates from inflammation and analgesia, and may be safe as an orally administered natural product for humans.

Protective effect of juice extract of mesocarp rind of Citrullus lanatus in carbon tetrachloride-induced oxidative stress in rats

Objective:To investigate the protective roles of juice extract of mesocarp rind of C. lanatus in carbon tetrachloride-induced oxidative stress in rats. Methods: Thirty albino rats were divided into six groups of 5 animals each, namely Groups A–F. The oxidant (CCl4) was used to induce oxidative stress in rats. It was administered as a single subcutaneous injection (2.0 mL/kg body weight) diluted 1:1 in paraffin oil on the 21st day. Animals in Group A (control) received 1 mL of distilled water;Group B received 1 mL of distilled water + CCl4;Group C received 100 mg/kg body weight ascorbic acid + CCl4;while Groups D, E and F were administered with 50, 100 and 200 mg/kg body weight ofC. lanatus extract + CCl4 respectively. The treatments were given once a day and lasted for 21 days. The levels of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferase (GST), reduced glutathione (GSH) and malondialdehyde (MDA) in the liver and serum were evaluated. Results:The assessment of antioxidant parameters revealed a significant (P< 0.05) hepatic oxidative damage in CCl4 treated albino rats, and this was considerably reversed to almost normal level in rats co-administered with juice extract of mesocarp rind ofC. lanatus at the dose level of 200 mg/kg body weight/day for 21 consecutive days. Conclusions:It can be concluded from this present study that the mesocarp rind ofC. lanatus is rich in antioxidants and thus suggesting the possibility of utilizing it as nutraceutical or functional foods to prevent or manage some critical complications in living cells.

Effect of Vigna radiata, Tamarix ramosissima and Carthamus lanatus extracts on Leishmania major and Leishmania tropica: An in vitro study

Objective:Current therapy strategies of leishmaniasis have some problems such as high cost,toxicity and side effects.Plant extracts can be a source of drugs to control leishmaniasis.In this study,the effect of hydroalcoholic and chloroformic extracts of Vigna radiata,Tamarix ramosissima,and Carthamus lanatus on Leishmania major and L.tropica was studied.Methods:The plant samples were collected from west of Iran and their extracts were prepared.Antipromastigote activity assay of all extracts was done using tetrazolium-dye assay.Results:Only high concentrations of V.radiata and C.lanatus were able to inhibit Leishmania,while both high and low concentrations of T.ramosissima had antileishmanial effect.No difference was observed between hydroalcoholic with chloroformic extract of each plant.Conclusion:Altogether,the results revealed the antileishmanial activity of T.ramosissima extracts against L.major and L.tropica,indicating its potential as an antileishmanial agent.

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。

^(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。

^(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。

西瓜品种和育种材料的DNA指纹分析

利用RAPD技术对国内外26份西瓜材料进行遗传亲缘关系研究、构建每份材料的特异指纹。在720个RAPD随机引物中筛选出15个引物用于聚类分析,将供试26份材料分为6个类群1个美国生态型类群、2个中间生态型类群、1个东亚生态型类群、2个野生类群。将京欣一号杂种纯度鉴定的RAPD特异标记K14-1500和N04-600成功转化为SCAR标记,并应用于京欣一号纯度鉴定实践。

氧肥对渍害胁迫下西瓜生理特性、产量及品质的影响

针对西瓜[Citrullus lanatus(Thunb.)Matsum.et Nakai]渍害胁迫,采用大田试验方法,研究了施用氧肥对西瓜在渍害胁迫下平作和垄作2种不同种植方式的生理特性、果实品质和产量的影响。结果表明,开花坐果期渍害胁迫对2种种植方式的西瓜生长都有抑制作用,但对垄作西瓜的影响较小,且氧肥对垄作渍害的缓解作用也最明显。施用氧肥的处理比单独淹水的平作和垄作处理其西瓜叶片的SOD活性分别提高了7.9%和9.3%,POD活性分别提高了15.0%和20.0%,MDA含量分别降低了25.9%和31.4%,叶绿素含量分别提高了40.3%和25.4%,西瓜果实维生素C、还原糖、瓜氨酸含量分别提高了14.8%、8.5%、9.1%和15.6%、8.8%、8.8%,产量分别提高了8.5%和10.5%。表明氧肥可以有效提高西瓜对渍害胁迫的耐受性,并能改善品质,提高产量。但不同种植方式施用氧肥的效果存在差异,垄作结合施用氧肥处理对缓解西瓜渍害胁迫的效果更明显一些。

吊蔓西瓜精准化栽培技术

为适应市场变化,开展了吊蔓西瓜[Citrullus lanatus(Thunb.)Matsum.et Nakai]精准化栽培技术研究,主要包括土地整理、种子处理、精准化栽培关键技术及采收等内容。西瓜吊蔓精准化栽培模式充分利用空间提高西瓜产量及效益,利于高效农业发展,农户增收。

转基因西瓜研究进展

综述了西瓜转基因常用的方法、目前已获得的转基因西瓜性状以及转基因西瓜安全性等方面的研究进展,并提出了今后进一步的研究方向。西瓜转基因常用方法为叶盘转化法;将外源基因导入到西瓜基因组中常用的方法主要有农杆菌介导法和花粉管介导法;常采用PCR、Southern和Western等方法来检测和鉴定外源基因是否成功整合到西瓜基因组中;目前利用转基因技术改良的西瓜性状主要集中在培育抗病毒、抗枯萎病和耐旱、耐盐碱等方面;对转基因西瓜的安全性研究主要包括生态安全性和食品安全性2个方面。今后应利用转基因技术进一步提高西瓜营养品质、耐贮性和抗冻性等性状,并进一步加强对转基因西瓜安全性的研究。

西瓜种子细菌性果腐病消毒方法研究

研究了物理方法(干热处理)、化学药剂(甲醛、盐酸、过氧化氢、次氯酸钠)以及杀菌剂对西瓜(Citrullus lanatus)种子细菌性果腐病消毒效果的影响。结果表明,3%的HCl和5%的甲醛处理20 min及0.5%或1%ZC处理1 h,对西瓜种子细菌性果腐病防治效果良好,对西瓜种子发芽率及发芽势无显著影响,且对种子胚根生长具有明显的促进作用,建议在生产上推广使用。

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.

锌对西瓜幼苗生长及产量与品质的影响

研究了锌对早春红玉西瓜(Citrullus lanatus)幼苗生长及产量和品质的影响。结果表明,在早春红玉生长过程中施用锌肥可以促进幼苗生长发育,提高早春红玉坐果数和单瓜重,显著提高早春红玉产量。锌肥可显著提高西瓜中糖和VC含量。根据试验结果建议在基肥中每公顷添加30 kg七水硫酸锌为宜。

Response of Watermelon to Gravel-Mulch and Supplementary Irrigation: Yield, Water Use Efficiency and Root Distribution

A field experiment was conducted to investigate the effect of supplementary irrigation on watermelon (Citullus lanatus) yield, water-use efficiency (WUE) and root distribution in gravel-mulched field in northwest Loess Plateau, China, during 2001 and 2002 growing seasons. The results showed that gravel mulch significantly improved seedling emergence, increased yield and WUE, and alleviated the influence of drought on plant growth. Regardless of gravel mulch application, supplementary irrigation increased watermelon yields, average fruit weight and number of fruit, especially yield increased as the amount of irrigation increased (P<0.05). Generally, WUE of irrigated treatments were higher than that of non-irrigation treatment in gravel-mulched field. The effect of water supply on root distribution was different in two years. In 2001, average root length density (RLD) and root weight density (RWD) whole the soil profile increased. In 2002, however, RLD and RWD decreased as water supply increased. The average RLD and RWD in 2001 were significantly higher than those in 2002. Maybe we can interpret the phenomenon with the theory that there is a need to optimize root distribution (in terms of water relations) and aboveground biomass for a given water supply.The yield may not depend as much on root growth as on the amount of water required at critical stages. A significant effect of soil depth on RLD and RWD were observed in both years, but did not rapidly decrease with depth.

西瓜叶绿素含量及荧光动力学参数与产量的多元回归和通径分析

为探讨不同氮浓度条件下西瓜(Citrullus lanatus)叶片光合性状的变化及其对产量的影响,以西瓜品种早春红玉为试验材料,分析不同氮浓度下其苗期、伸蔓期、开花期、膨果期叶片叶绿素含量和叶绿素荧光动力学参数的变化情况以及氮浓度与产量的关系。结果表明,氮浓度、叶绿素含量及叶绿素荧光动力学参数与西瓜产量之间存在极显著的线性关系,叶绿素含量和叶绿素荧光动力学参数与西瓜产量的回归方程为:Y=-3.018+0.012 X氮浓度-0.004 3 XSPAD-0.017 X初始荧光-0.001 X可变荧光-0.002 8 X最大荧光+0.015 X潜在活性+5.07 X光能转化效率;氮浓度、潜在活性和光能转化效率与产量均呈正相关,而初始荧光、SPAD值、可变荧光和最大荧光与产量呈负相关;各参数对西瓜产量的影响从大到小为光能转化效率、初始荧光、最大荧光、氮浓度、可变荧光、SPAD值、潜在活性;光能转化效率、初始荧光和最大荧光对产量的影响取决于直接作用,潜在活性、可变荧光和SPAD值对产量的影响取决于间接作用;氮浓度与产量的相关是直接作用和间接作用共同的影响。

A Reliable Methodology for Quantitative Extraction of Fruit and Vegetable Physiological Amino Acids and Their Subsequent Analysis with Commonly Available HPLC Systems

Many of the extraction and amino acid analysis methodologies currently employed do not provide complete analysis of all the physiological amino acids and biogenic amines. Extraction procedures frequently employ dilute acid which partially converts gln and asn to glu and asp. A commonly used pre-column derivatizing agent, o-phthalaldehyde, does not react with the imino acids, pro and hydroxypro. The purpose of this investigation was to integrate extraction and analysis procedures into a reliable method for measuring the complete physiological amino acid profiles of fruit and vegetables using HPLC instrumentation commonly available to most laboratories. Water extraction of ground, frozen-thawed tissues effected complete recovery of the physiological amino acids as demonstrated by spiking experiments and tissue combination experiments. HPLC of dabsyl derivatives of the free amino acids allowed their quantification in a selection of fruit and vegetables. Physiological amino acid levels were determined for peach, apple, potato, onion, tomato, bell pepper, broccoli, and seven types of cucurbits. The coefficient of variation for estimation of an amino acid level generally fell in the range of 5% to 7%. Because of marked variability in physiological amino acid content as a result of growing conditions, cultural practices, and inherent cultivar differences, comparisons of results with literature values were not possible.