Differential response of zucchini varieties to low storage temperature

Several parameters related to cold damage in zucchini have been measured in fruits from different varieties cultivated in the province of Almería (south-eastern Spain). The purpose of this work is to correlate physiological parameters with commercial quality and chilling damage, in order to establish reliable criteria for selecting varieties having better genetic adaptation to low-temperature storage. The results show that, for varieties harvested during February, the variety Natura was the best adapted to storage at 4 °C, as its fruits suffered less from chilling injuries, had a lower weight loss, and the levels of metabolites malonyldialdehyde and H₂O₂ were not as high as in the other varieties. Genetic variation was detected for some of the parameters analysed. The positive correlation among the levels of MDA, H₂O_2, and chilling injury, as well as the negative correlation among catalase and chilling injury, makes these parameters good indicators of chilling damage in our system.     

Use of low-pressure storage to improve the quality of tomatoes

Freshly harvested vine-ripened tomatoes (Solanum lycopersicum cv. Neang Pich) were stored at low pressure (4 kPa) at 10°C for 11 days with 100% RH. Fruit quality was examined upon removal and after being transferred to normal atmosphere (101 kPa) at 20°C for 3 days. Weight loss was significantly lower in fruits which were stored at low pressure (4 kPa) than in fruits that were stored at regular atmosphere (101 kPa) at 10°C. Fruits that were stored at low pressure (4 kPa) reduced calyx browning by 12.5%, and calyx rots by 16%, compared to fruits that were stored at regular atmosphere (101 kPa) at 10°C. Fruit firmness was not significantly different between fruits stored at low pressures (4 kPa) and the normal atmosphere (101 kPa), with an average firmness of 14 N after fruits were stored at 10°C for 11 days. There was no difference in the SSC/TA ratio. The results suggest that a low pressure of 4 kPa at 10°C has potential as an alternative, non-chemical postharvest treatment to improve tomato quality during storage.     

不同储存方式对猕猴桃维生素C含量的影响

以探讨不同储存方式对猕猴桃维生素C（Vc）含量的影响为目的,采用2,6-二氯靛酚滴定法测定不同储存方式下猕猴桃维生素C含量的变化。结果显示,3种储存方式下,猕猴桃Vc含量及保存率随储藏时间的增加均呈下降趋势,低温储存对猕猴桃Vc含量和保存率的影响最小,干制对猕猴桃Vc含量及保存率的影响最大,猕猴桃应尽量选择鲜食。     

不同龙眼品种果实品质和糖酸组分分析

以12个龙眼品种的果实为试材,利用常规的品质分析和高效液相色谱技术,进行了果实品质和糖酸组分分析。结果表明,品种间果实质量和可溶性固形物含量差异较大,分别为6.1～15.1g和12.2%～23.0%。可食率最高为双孖木(71.4%),最低为沙梨木(56.2%)。果糖、葡萄糖和蔗糖是龙眼假种皮的主要糖类,但不同品种这3种糖的比例有较大差异,根据单糖与双糖的比例,可将不同的龙眼品种分为3个类型:蔗糖积累型,还原糖积累型和中间类型。龙眼假种皮中的有机酸含量较低,为1.46～3.46mg/g,主要有苹果酸、草酰乙酸、α-酮戊二酸、草酸、柠檬酸、酒石酸和奎尼酸,不同品种有机酸的含量和比例有一定的差异。龙眼假种皮中也有较丰富的还原型抗坏血酸(维生素C),约占总酸的12.4%,不同品种维生素C含量有较大差异,储良最低(0.13mg/g),罗伞木最高(0.65mg/g)。     

1-MCP对不同成熟度白凤桃冷害发生的影响

以白凤桃果实为材料,研究了1-甲基环丙烯(1-MCP)对低温冷藏条件下果实成熟生理和冷害发生的影响。实验采用25μL/L1-MCP分别对底色转白期(MG)和成熟期(RR)桃果实进行处理,然后置于(0±1)℃冷库中贮藏24d。结果表明,1-MCP处理都能够延缓MG和RR果实的后熟软化进程,降低乙烯释放量,并抑制了果实快速软化阶段的PG酶活性;1-MCP处理提高了贮藏后期MG果实的硬度,降低了出汁率,加剧了冷害的发生程度,1-MCP处理对RR果实的冷害发生率没有显著影响,表明1-MCP对桃冷害的发生程度与果实成熟度有关。     

Defense response of tomato fruit at different maturity stages to salicylic acid and ethephon

In order to elucidate whether fruit maturity stage influence the induced resistance of exogenous elicitors in tomato and the involved mechanisms, we investigated the defense responses of tomato fruits against Botrytis cinerea, ethylene production and internal quality following treatments of fruit with salicylic acid (SA) or ethephon (ET) at mature green (MG) and breaker (BR). SA significantly suppressed decay and disease incidence in tomato fruits at both MG and BR stages, along with higher expression level of PR1 gene after 2 days of treatment. All fruits treated by SA had lower contents of ethylene and lycopene. The ET-treated fruit at both maturity stages showed lower disease incidence and higher level of PR2 and PR3 expression compared with the control fruit. ET treatment significantly enhanced ethylene and lycopene contents, and accelerated fruit ripening. Our results suggest that SA and ET induced disease resistance in fruits by mediating the expression of different pathogenesis-related genes and have different effects on fruit ripening, which in turn influences the disease resistance of tomato fruits.     

MAP贮藏对甜樱桃品质的影响

对甜樱桃的贮藏保鲜试验表明,MAP与专用保鲜剂结合可有效地保持果实的鲜食品质,减少果实的腐烂和褐变,降低果实的呼吸强度,延长果实的贮藏期.‘红灯‘甜樱桃贮藏保鲜80 d果实的腐烂率为3.62%;对照果实只贮藏了40 d.‘雷尼‘甜樱桃贮藏保鲜110 d果实的腐烂率为2.1%,褐变率为0,果柄抽干率为0.32%;对照果实只贮藏了50 d.     

温度和PE袋包装对皖金猕猴桃果实采后品质变化的影响

[目的]探究猕猴桃新品种皖金的采后贮藏特点,明晰其适宜的贮藏温度及包装膜袋厚度.[方法]试验分为两部分:首先将部分果实分别放入(0±0.5)℃、(1±0.5)℃、(2±0.5)℃,相对湿度(90±5)％冷库以及常温(CK1)下贮藏,定期取样测定相关指标,确定皖金适宜贮藏温度;在上述适宜贮温基础上,进一步优化贮藏条件,采...     

宁夏贺兰山东麓不同葡萄品种对霜霉病的抗性鉴定

为了给葡萄抗性品种的选育和葡萄霜霉病的防治提供科学依据,对16个不同酿酒葡萄品种和19个鲜食葡萄品种的抗病性进行了抗性测定。结果表明,室内回接与田间调查结果一致,16个酿酒葡萄品种可划分为4类;19个鲜食葡萄品种可划分为4类;从发病时间来看,抗性与发病时间存在一定相关性,抗性越强发病越晚。随即将测定结果采用DPS软件进行聚类分析,在酿酒葡萄抗性反应谱系图上,第1类为抗性稍强品种,为白比诺、灰比诺和赛美蓉;第2类为抗性中等品种,由白长相思和神索等8个品种组成;第3类是稍感病品种,包括赤霞珠等4个品种;第4类是感病品种,只有品丽珠1个。在鲜食葡萄谱系图上,第1类为六月紫等7个抗性稍强品种;第2类是新华1号和巨峰;第3类是稍感品种,由奥古斯特等6个品种组成;第4类为力扎马特等4个感病品种。     

不同土壤水分条件下草莓果实在模拟贮运中的损伤易感性

通过模拟运输振动实验研究了种植在不同土壤水分条件下草莓果实在贮运中的损伤易感性。试验结果表明,栽培在较高土壤水分条件下的果实含有较高的水分,贮运中果实损伤易感性与果实含水量、果实鲜重、土壤湿度呈显著或极显著相关。模拟振动实验发现:在高土壤水分条件下栽培的草莓果实在振动前、振动后及贮藏后的呼吸速率分别为生长在低土壤水分果实的124.9%、119.0%和133.2%。振动的果实比未振动的果实降低了28%-36%的蔗糖,增加了4.5%-9.8%的果糖和7.1%-10.1%葡萄糖,说明运输振动促进了蔗糖降解为葡萄糖和果糖的水解过程。     

红色砂梨2个品种着色过程中的外观变化及其解剖学结构观察

以红色砂梨(Pyrus pyrifolia Nakai)品种美人酥和云红梨1号为试材,以套袋处理(果袋类型、去袋方式和去袋时间组合成10个不同的套袋处理)为手段研究了果实着色过程中外观和解剖结构的变化。结果表明,红色砂梨的着色需要有高强度的光照。生长过程中套有不透光袋的果实临近成熟时,只有完全曝光才能大量合成花青苷,而且在很短的时间内(大约2周)果实着色面积、着色程度即可优于对照(不套袋处理)。红色砂梨着色是从果实向阳的一侧先开始,且以果点为中心呈放射状向四周扩展,至采收时果实阳面红色能够均匀分布,但整个果面色泽很难一致。解剖结构分析表明果面呈红色是因为果皮中紧邻表皮层的3～4层细胞存在红色细胞(含有花青苷),在果实着色过程中这些红色细胞数目不断增多,同时细胞内色素浓度不断增大。云红梨1号合成花青苷的能力明显优于美人酥,果实着色更鲜艳。解剖学观察发现云红梨1号的表皮细胞层也含有红色细胞。     

采前钙钾处理对甜樱桃果实品质和贮藏效果的影响

在预备试验基础上,于采收前15 d,通过3个浓度Ca(NO3)2与KH2PO4配合对甜樱桃喷布,结果表明,处理的果实品质好于对照,Ca2 K 能够抑制果实中POD、PPO活性,降低MDA含量,并且随浓度增加抑制作用增强,Ca2 K 处理果实腐烂率比对照降低1.34%～13.54%,褐变率降低10%～25.3%.     

A comparison of the combined effect of water stress and crop load on fruit growth during different phenological stages in young peach trees.

Summary

The combined effect of fruit load and water stress on fruit water content and dry-matter accumulation was analysed for three phenological stages of fruit growth. Irrigation treatments were no irrigation during Stage I (NI-SI), Stage II (NI-SII), or Stage III (NI-SIII) compared with a fully irrigated control. Three thinning treatments were imposed within each irrigation treatment resulting in fruit loads ranging from low to high. Fruit harvests at the end of Stage I, II and III were used to determine total tree fruit fresh and dry matter after each stage of fruit development. Fruit water accumulation was highly sensitive to the effect of water stress at high fruit loads in all fruit developmental phases, but reductions in fruit water content were more apparent during Stages II and III than during Stage I. On the other hand, fruit dry-matter accumulation was relatively insensitive to water stress at any fruit load level and developmental stage. However, reductions in dry-matter accumulation were obtained during Stage III from those trees that were not irrigated during Stage I (NISI). Since these reductions occurred only for mid-to-high fruit load conditions, the decreases in fruit growth during Stage III appeared to be related to a carbon source limitation. The possible reasons for this source limitation are discussed.     

Responses of banana fruit to pro-long coating at different times relative to the initiation of ripening

Coating banana fruit with Pro-long 24 h after initiation of ripening decreased their skin permeability to gases and depressed their O₂ content. Coating the fruit immediately before ripening initiation delayed the onset of rapid ethylene production, which normally begins as the fruit start to ripen. Coating slightly suppressed rapid C₂H₄ production when applied immediately after ripening initiation, and exerted a strong, temporary inhibition of C₂H₄ production when applied 24 h later. A climacteric rise in respiration was absent from fruit coated with Pro-long immediately before or after ripening initiation; delaying coating by a further 24 h arrested development of the climacteric in mid-rise. In mid-climacteric fruit, inhibition of C₂H₄ production by coating occurred more rapidly than inhibition of respiration. Coating the fruit delayed the chlorophyll loss which normally accompanies ripening, but the magnitude of this effect declined as the coating treatment was delayed relative to ripening initiation. The effects of coating on skin colour change and on respiration appeared to be largely independent of its effect on the fruit's C₂H₄ content.     

杧果抗炭疽病种质资源的鉴定与分析

炭疽病是杧果的重要病害,在对此病害的综合防治中,选种抗病品种是行之有效的措施。本研究运用杧果炭疽病高致病性菌株,对保存在中国热带农业科学院南亚热带作物研究所杧果种质资源圃的果品种抗病性进行了初步鉴定。结果表明,大部分的果品种为感病品种,其中爱文杧、乳杧、海豹、龙井大杧等为高感品种;紫花杧、金煌、实选-4、spooner为高抗品种;台农一号、粤西一号、台牙、贵妃、Mallika、桂香、凯特等为中抗品种;在所有供试品种的抗病鉴定中,没有发现免疫品种。     

Content levels of various fruit metabolites in the ‘Conference’ pear response to branch bending

The response of ‘Conference’ pear subjected to branch bending in the content levels of various metabolites in its fruit was investigated. The fruits in commercial maturity were sampled in 2004 and 2005 from branches bent in the late summer of 2003 (the summer treatment), from branches bent in the late spring of 2004 (the spring treatment) and from control branches. The content levels of carbohydrates, organic acids and phenolic compounds were compared among treatments in two successive years. The fruit revealed various responses in content levels of metabolites. In the first year after bending, no significant differences were found in the content of each carbohydrate, but in 2005 by far the highest content level of glucose and fructose and the lowest content level of sucrose were found in fruits from the control. The control fruit showed significantly higher content levels of malic acid and lower content levels of some phenolics (chlorogenic and vanillic acid) in the first year after bending, but in the next year the opposite reaction occurred—the control fruit had the lowest content level of malic acid and the highest content level of epicatechin, quercetin-3-d-galactoside and quercetin-3-β-d-glucoside. The comparison of the two bending treatments alone in 2004 showed that the summer treatment often produced a slightly higher value of each phenolic in comparison to the spring treatment. However, in 2005 the significantly highest content of chlorogenic acid was in fruit from the spring treatment. Sorbitol, as well as citric acid, catechin and sinapic acid showed no clear tendency among treatments, neither in 2004 nor in 2005. It is suggested that these variations of ‘Conference’ fruit subjected to different bending treatments could not be the result of bending alone, but that they could be indirectly affected by other physiological responses of the fruit tree. However, it seemed that variations are affected by the time of bending and by the year-to-year, and such responses can be attributed to the ‘Conference’ genotype only.     

A comparison of the application of different waste products to a lettuce crop: Effects on plant and soil properties

A romaine-type lettuce (Lactuca sativa L.) was cultivated during three successive crop seasons in an agricultural land near the Wastewater Treatment Plant (WWTP) of Alcázar de San Juan. Four fertilization treatments were compared, including: two different organic fertilizer treatments consisting of (i) air-dried sewage sludge (SS), and (ii) municipal solid waste compost (MSWC), (iii) an inorganic treatment of commercial fertilizer (FER), and (iv) a control treatment in which no fertilizer was applied (CONT). The highest yield was observed in the SS treatment in all crop seasons. In the organic treatment plots there was an increase in macronutrients and organic matter in the soil. An accumulation of heavy metals in the soil was not observed but there was an increase in microbial population in the organic treatment plot, especially in the SS treatment plot. In plant tissue, the continued addition of fertilizers did not produce an accumulative effect of macro- and micronutrients. Low heavy metal content (Cr, Cd, Pb and Hg) was observed in all treatments and crop seasons. Microbiological content was more numerous in the first crop season in SS-treated plants, mainly in lettuce leaves but also in the soil.     

Demarcating specific ion (NaCl, Cl, Na) and osmotic effects in the response of two citrus rootstocks to salinity

The present work differentiates the effects of NaCl, Cl⁻, Na⁺ and concentrated macronutrients on two citrus species, sour orange (Citrus aurantium L) and Macrophylla (Citrus macrophylla Wester). Plants were grown in a base nutrient solution (0.07 MPa osmotic pressure) for 4 months before applying the treatments that consisted of isotonic solutions of 0.23 MPa osmotic pressure of Na⁺ (40 mM, without Cl⁻), Cl⁻ (40 mM, without Na⁺), NaCl (40 mM) and 3.5 times the concentration of macronutrients of the base solution. Plants were grown in the different treatment for 2 months before being examined for symptoms of toxicity. The two genotypes showed major differences in the extent of Cl⁻ and Na⁺ accumulation in leaves and in their ability to maintain the internal concentrations of essential nutrients in response to the different ionic compositions of the medium. Differences in mineral nutrient accumulation were observed among treatments in both rootstocks. It was concluded that growth response to the different treatments was primarily affected by an osmotic effect, although in Macrophylla, the ionic effects also seem to be present.     

A frame-based spatially explicit model of subarctic vegetation response to climatic change: comparison with a point model

An important challenge in global-change research is to simulate short-term transient changes in climate, disturbance regime, and recruitment that drive long-term vegetation distributions. Spatial features (e.g., topographic barriers) and processes, including disturbance propagation and seed dispersal, largely control these short-term transient changes. Here we present a frame-based spatially explicit model (ALFRESCO) that simulates landscape-level response of vegetation to transient changes in climate and explicitly represents the spatial processes of disturbance propagation and seed dispersal. The spatial model and the point model from which it was developed showed similar results in some cases, but diverged in situations where interactions among neighboring cells (fire spread and seed dispersal) were crucial. Topographic barriers had little influence on fire size in low-flammability vegetation types, but reduced the average fire size and increased the number of fires in highly flammable vegetation (dry grassland). Large fires were more common in landscapes with large contiguous patches of two vegetation types while a more heterogeneous vegetation distribution increased fires in the less flammable vegetation type. When climate was held constant for thousands of years on a hypothetical landscape with the same initial vegetation, the spatial and point models produced identical results for some climates (cold, warm, and hot mesic), but produced markedly different results at current climate and when much drier conditions were imposed under a hot climate. Spruce migration into upland tundra was slowed or prevented by topographic barriers, depending on the size of the corridor. We suggest that frame-based, spatially explicit models of vegetation response to climate change are a useful tool to investigate both short- and long-term transients in vegetation at the regional scale. We also suggest that it is difficult to anticipate when non-spatial models will be reliable and when spatially explicit models are essential. ALFRESCO provides an important link between models of landscape-level vegetation dynamics and larger spatio-temporal models of global climate change.     

Chitinase and β-1,3-glucanase enzymatic activities in response to infection by Alternaria alternata evaluated in two stages of development in different tomato fruit varieties

Chitinase (ChA) and β-1,3-glucanase (GA) activity had been related with plant defense mechanism against pathogen attack in vegetative tissues. Scarce information is available about the behavior of these enzymes in response to different stages of development and fungi infection in fruits. The changes in ChA and GA activities in response to Alternaria alternata infection were evaluated in mature green (MG) and red ripe (RR) developmental stages of Sunpride, Geronimo and Charleston varieties of tomato fruit. Tomato fruits were inoculated with a conidial suspension of A. alternata and stored for 10 days at 25 °C and 90–92 H.R.%. The degree of fruit infection was measured by a hedonic scale every 2 days. ChA activity was determined fluorometrically by quantifying the release of 4-methylumbelliferyll (4-MU) from 4-methylumbelliferyll β-d-N,N′N″-triacetylchitotrioside, and GA activity was measured quantifying the release of glucose from β-1,3-glucan (laminarin) by HPLC. Tomato fruit in RR stage was more susceptible to fungi infection than MG stages. Geronimo was the most resistant variety, whereas Sunpride was the most susceptible for both stages of development (MG and RR). Higher levels of ChA and GA activities were observed for mature green stage in Charleston variety at the end of the storage period. An induction in ChA and GA in response to infection by A. alternata was observed in all varieties. Particularly high levels of ChA were found for inoculated Geronimo in RR stage and inoculated Charleston in MG stage which correlated with low levels of fungi infection. Higher levels of GA induction in response to fungi infection were recorded for Sunpride variety in RR stage, whereas no substantial induction was observed for Geronimo and Charleston varieties at the same stage of development. This GA induction correlated negatively with the resistance showed by the different varieties to fungi infection. We concluded that chitinase and β-1,3-glucanase induction are part of the tomato fruit defense mechanism against A. alternata infection with a different behavior depending upon stage of development and variety.