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Using young fruits or fruit segments, rates of penetration of 45CaCl2 across apple fruit cuticles (Malus x domestica) were studied during fruit development in two consecutive years (’?Golden Delicious’ in 2000, ’?Cox Orange Pippin’ and ’?Boskoop’ in 2001). The aqueous donor solutions contained 5 g l—1 CaCl2 and 0.2 g l—1 Glucopon 215 CSUP as wetter. A droplet (5 μl) was applied to each fruit disc and allowed to dry within 1 h. Amounts penetrated were estimated immediately after droplet drying (0 h) and after 6 and 24 h penetration, respectively. Temperature during penetration was 20 ?C and 100 % humidity was maintained throughout the experiment, once the droplet had dried. Rates of penetration were greatly affected by the stage of fruit development. With all varieties tested, highest rates were measured during the early stages of fruit development (before June drop) when approx. 100 % of the CaCl2 applied penetrated within 24 h. After June drop, when trichomes had vanished and most stomata developed into lenticels, penetration rates decreased rapidly and large variability among the samples developed. This pattern was similar with all three varieties. The involvement of trichomes, stomata, and lenticels as preferential sites of penetration of calcium chloride across the apple fruit cuticles is discussed. Using a model calculation, it is argued that ten or more spray applications are needed to significantly increase calcium contents of apples. This has two causes: Only a small fraction of the spray liquid is intercepted by the fruits, and penetration can be rather slow. 相似文献
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本研究采用轮纹病菌分生孢子和菌丝接种不同龄期的苹果枝条,检测枝条皮孔发病率,以明确不同龄期苹果枝条对轮纹病菌的抗病性差异.结果表明,当年生‘富士’苹果枝条的幼嫩部分接种后发病最重,皮孔的发病率达80％以上,随枝条的生长发育,抗病性逐渐增强,枝条发育成熟后,皮孔发病率降至40％左右.在7月份接种的1～5年生‘富士’苹果成熟枝条中,皮孔的发病率没有显著差异.在8月份接种的‘富士’苹果枝条中,1年生枝条的皮孔发病率显著高于5年生枝条的发病率.未发育成熟的苹果枝条对轮纹病菌的抗侵入能力差,枝条发育成熟后抗病能力明显增强.1～5年生枝条上发育完整的皮孔对轮纹病的抗侵染能力没有显著差异,但在枝条的迅速加粗生长期,低龄枝条上皮孔结构变化更大,对轮纹病菌的侵入也更敏感. 相似文献
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Isolates of Penicillium spp. were collected regularly from 2001 to 2003 from the surfaces of apple fruit pre- and postharvest, and from the atmosphere of orchards and storage rooms in France. Penicillium spp. were not detected from the atmosphere of conventional orchards, while their density did not exceed 50 spores m−3 in the atmosphere of organically managed orchards. Penicillium spp. were seldom detected on apple surfaces in the orchard. The density of Penicillium on apples increased from 10 to 50 spores cm−2 after 1 month in storage to 300–400 spores cm−2 after 6 months. The level of airborne Penicillium increased by up to 2 × 104 and 2·5 × 103 spores m−3 within nondisinfected and previously disinfected warehouses, respectively. Penicillium expansum (30–62%) and P. solitum (6–45%) were the most prevalent species on apple or in storage rooms. Other species of Penicillium isolated included P. commune, P. verrucosum, P. chrysogenum, P. rugulosum and P. digitatum. Apple fruit were also surveyed for wounds and the number of open lenticels using the sulphur dioxide test. The incidence of wounding at harvest varied from 12 to 36%, depending on cultivar and locality. When apples were inoculated at harvest by either aqueous or aerial inoculum of P. expansum, the decay incidence was constantly higher than the incidence of wounding. The number of open lenticels per cm2 of apple surface varied from 0·5 on cv. Boskoop to 4·4 on cv. Golden Delicious. An average of 13 and 2·1% of lenticels, respectively, were infected when they were inoculated by P. expansum and P. verrucosum. Cultivars of apple fruit that showed a greater number of open lenticels, combined with a large diameter varying from 100 to 200 µm, were more susceptible to P. expansum. 相似文献
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Foliar applications of calcium salts are usually combined with fungicides. In the years 2002 and 2003, it was tested if this practice assures high rates of penetration of calcium. Amounts that penetrated in 24 h were measured at 20 °C using 45CaCl2. To ensure maximum penetration rates, humidity was maintained at 100 %. Sample size was 40 to 50 fruits, and data were presented as box plots because distribution of data was not normal. Median rates of penetration of CaCl2, measured with mixtures of fungicides and CaCl2 at 5 or 10 g l–1, respectively, were very slow, and amounted to only a few percent of the dose applied. Rates were a little higher with very young fruits (55 days after full bloom, DAFB). Adding alkyl polyglycoside surfactants at 0.2 g l–1 significantly decreased surface tensions, and increased rates of penetration by up to 15‐fold. Still, total penetration of CaCl2 rarely exceeded 20 % of the dose applied (median penetration), even in the presence of an additional surfactant. In all treatments, outliers with 60 to 100 % penetration in 24 h occurred, and this was attributed to penetration into lenticels. This is expected to result in unequal concentrations of calcium in fruits, especially in the sub‐epidermal layers. Addition of a suitable surfactant to mixtures of fungicides with CaCl2 is strongly recommended as it enhances wetting and greatly increases penetration rates of CaCl2. 相似文献
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【目的】研究栓皮栎软木中的杂质与纯软木的不同,以有效去除软木中的夹砂和夹杂。【方法】以陕西产栓皮栎软木为材料,分析其杂质的结构及主要化学成分的质量分数,并与纯软木细胞进行比较。【结果】夹砂的细胞排列紧密,细胞壁较厚,为白色,细胞腔内充有白色物质,其木栓脂、纤维素和木质素的质量分数分别为1.65%,28.57%和26.31%;夹杂的细胞整体上排列比较疏松,细胞间隙发达,其木栓脂、纤维素和木质素的质量分数分别为2.20%,23.61%和24.32%;纯软木细胞为充满空气的薄壁细胞,相邻细胞交错排列,且排列紧密,无细胞间隙,似蜂窝状,其木栓脂、纤维素和木质素的质量分数分别为38.93%,7.89%和21.64%。【结论】栓皮栎软木中夹砂和夹杂与纯软木细胞的结构、主要化学成分的质量分数均不同,因而性能也不同。纤维素和木质素的质量分数高,木栓脂的质量分数低,是软木杂质硬而脆、弹性小的主要原因。 相似文献
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为探索不同家系北美鹅掌楸的耐淹性差异,采用盆栽苗模拟淹水法对Louis（L）,Kent（K）和Penn（P）3个家系的2年生幼苗进行处理,研究皮孔、膝根、绿叶等指标的变化情况。结果表明：膝根形成是北美鹅掌楸淹水胁迫的应激反应,同一家系随胁迫水位高度的增加膝根长度和粗度分别呈增长和增粗的趋势,不同家系膝根生长量存在差异,L家系膝根最长、最细,P家系增粗最快,K家系居中;通气组织皮孔的形成增高了北美鹅掌楸的耐淹性,皮孔数L家系＞K家系＞P家系;在淹水条件下植株表现为枯死及绿叶数减少,其中K家系绿叶数最多,不同家系表现存在差异;水中穿孔根的生长提高了地上/地下部分比值,增加吸氧表面积而提高耐淹性能,是一种应激反应。3个家系耐淹性强弱依次为L家系＞K家系＞P家系,膝根长度和皮孔数量与北美鹅掌楸耐水能力直接相关。 相似文献
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[目的]枣果实成熟期遇雨易开裂,会带来巨大的经济损失。明确引起枣果实开裂的水分吸收主要途径,为进一步探明枣裂果机制和科学防控提供依据。[方法]于2013—2015年,以易裂果的‘壶瓶枣’果实为试材,通过染液示踪结合体视镜观测枣果实不同部位的吸水分布,确定枣果实可能的吸水途径;通过蜡封果实不同部位结合浸水处理,测定枣果实不同部位单位时间内吸水量的差异;利用体视镜和扫描电镜观测枣果实表面结构特征,分析枣果实表面结构特征变化与吸水和裂果的关系。[结果]1）‘壶瓶枣’果实的果面、果梗和梗洼部位均可吸水,在易裂果的果实着色期3个部位的相对吸水量分别占51%~54%、31%~40%和9%~18%。2）枣果实发育成熟过程中,果面气孔木栓化形成皮孔,部分皮孔形成微裂隙,果面吸水量成倍增加;水分可以通过开放的皮孔和微裂隙进入果实,吸水途径包括共质体途径吸水和质外体途径吸水。3）自然降雨形成的裂果和浸水试验中的裂果上均普遍观察到宏观裂纹经过2个以上的果点连接成线、交叉裂口的交叉点为果点所在位置,证明枣果实表面气孔是引起果实宏观开裂的诱因。[结论]枣果面气孔在果实成熟进程中形成的皮孔和微裂隙是果实吸水的主要部位,也是枣果实吸水开裂的诱因;果实表面同时存在水分进入果实内部的共质体途径和质外体途径。 相似文献
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