【作者】 马海军；

【导师】 张继澍；

【作者基本信息】 西北农林科技大学 ， 植物学， 2010， 博士

【摘要】 同遭受其它逆境一样,植物对病害和机械损伤也有其适应性机制,产生相应的防御反应,这些防御反应既有生理生化反应,也会发生系列物理变化(其中以电学参数变化的测定更加快速、灵敏、成本低、且易于实现在线测定),它一方面有助于受损伤部位愈合,另一方面诱导全身反应进一步阻止伤害的发生。另外,伤害的出现和发展,也是病源微生物的入侵之门,是导致采后水果霉烂的重要原因之一。但不论是损伤果还是病害果进行人工分拣既影响了果品的及时入库从而给果品品质带来不利影响,又需要大量的人力、财力,还很容易给果品带来二次伤害。因此,水果碰撞损伤和病害果的快速有效检测是目前研究的难点和热点之一。另外,作为植物调节物质的茉莉酸(jasmonic acid,JA)与植物抗性及伤信号分子转导密切相关,越来越引起人们的关注。为此,本文以西北农林科技大学白水县试验站的富士苹果为试材,应用LCR电子测试仪(日产)、生理生化技术、灰色系统理论与方法,分别研究了苹果红点病、虎皮病及碰伤48 h内果实电学特性变化规律、碰伤48 h内生理生化和以JA为主导的伤信号转导途径中脱落酸、乙烯、一氧化氮和水杨酸的变化及其相互关系,通过揭示苹果采后病害和机械损伤响应的部分电学特性和生理生化变化机制,证明用电学参数标志苹果采后病害和机械损伤响应的可行性,建立标志苹果品质特性(电特性和生理特性)动态变化的数学模型,为果实采后电特性变化及JA伤信号转导理论提供实验证据,为创建果实质量的无伤害检测新技术和进一步研制开发果实品质的无损检测仪器提供一定理论依据。取得的主要研究结果如下：1.通过应用LCR电子测试仪对富士苹果14个电学参数的测定表明：复阻抗(Z)的倒数值与导纳(Y)值相等,即Z-1=Y；当测定频率大于398 Hz时,其损耗系数(tanδ或D)的倒数值约等于Q因子(Q),即D-1≈Q(f>398Hz)；果实并联等效电感(Lp)、电抗(X)和Z之间存在着极显著的相关。综合上述分析,对LCR测试仪的14个电学参数,只需检测如下7个电学参数：Z、阻抗相角(θ)、并联等效电容(Cp)、损耗系数(D)、并联等效阻抗(Rp)、电导(G)、和电纳(B)。2.在20℃恒温条件下贮藏70 d的富士苹果红点病果实,随着频率(100 Hz、1 kHz、10 kHz、100 kHz和1 MHz)的增加,不论是病果还是正常果其果实的介电常数(s’)、复阻抗(Z)、电抗(X)和电感(Lp)值均在减小；果实的Z、X和Lp间存在着显著的相关；方差分析表明,病果和正常果的Z、X和Lp间差异均不显著(P>0.05),但两者的介电常数(ε’)和损耗因子(tanδ)差异显著(P<0.05)。tanδ和ε’基本可以反映水果的实际品质情况。3.富士苹果在(20±1)℃恒温条件下贮藏1d、8 d、15 d、22 d和29 d,随着频率(100 Hz-3.98 MHz)的增加,虎皮病果实的Z和X在减小,G则在增加；果实的Z和X间存在着强烈的相关；病果和正常果的各电参数变化趋势一致,但数值有很大不同,而且在Cp间存在显著差异。可以用Cp来挑分感病果实。4.40 cm和70 cm高处自由跌落至大理石地面上碰伤的富士苹果损伤后0 h(伤害后立即测定时间)、0.5 h、1 h、2 h、4 h、8 h、12 h、24 h和48 h,果实Z与B呈极显著的负相关,果实的Rp与G的绝对值相等,即|G|=Rp；40 cm处碰伤的果实和70 cm处碰伤的果实与正常果,在100 Hz-3.98 MHz频率下,其Z和Cp在同一个伤害时间内随频率的增加差异明显,基本可以正确反映水果的伤害情况；碰伤果和正常果最佳区分的电参数频率为10 KHz。5.富士苹果不同高度(40 cm和70 cm)跌落碰伤处理48 h内,碰伤处理明显使富士苹果的呼吸作用加强,而且伤害越大,其呼吸速率越高；诱导了果实伤乙烯的生成；(?)O2-产生速率和H202含量迅速增加,相应的保护酶(SOD、CAT、POD和PAL)活性也提高。表明碰撞损伤后虽然在一定程度上能引起果实膜脂过氧化,进一步导致果实伤害,加速衰老,但还可以诱导抗性加强：果实呼吸速率和乙烯释放速率提高,活性氧代谢加强,有利伤口愈合和阻止损伤发展。6.富士苹果在室温贮藏条件下不同高度(40 cm和70 cm)跌落碰伤处理48 h内,可诱导果实内源JA含量迅速增加；LOX活性、内源ABA含量和乙烯释放速率迅速升高,NO含量则呈下降趋势,但ABA出现高峰的时间要晚于JA高峰出现的时间,伤害刺激后Eth增长的幅度要远小于JA增长的幅度；游离态SA、结合态SA以及总SA含量,都呈急速下降趋势,在很短的时间内降幅都超过了70%；当JA含量出现高峰时,与之相对应的游离态SA含量正好处于低谷。7.通过对70 cm高处摔伤后0-48 h苹果理化特性与电学特性的同步测定和灰色关联分析法研究显示,各理化特性指标对电学特性指标有不同程度的影响；用灰色系统理论的GM(1,6)模型建立了苹果品质多因子动态变化的数学模型,可确定苹果理化特性的各项指标对电学参数的影响与作用；用灰色系统理论的GM(1,2)模型确定了苹果电学特性与理化特性之间的关系,认为可用Cp和Rp描述苹果的TSS,用Rp描述苹果的TA；建立了deg和Cp灰色系统理论的预测模型GM(1,1),通过验证,确定了预测模型的可用性。因而认为,用电参数预测苹果的损伤是可行的,有一定的理论意义和实用价值。更多还原

【Abstract】 Plant has developed adaptive mechanisms to protect themselves against disease and mechinary damages, which may be the same way as suffering other stress when not only physiological and biochemical responses occurs but also a series of physical change is produced. The responses can promote the healing of wound in one hand and induce systemic reactions to hinder the development of damages on the other. Impact injury can open the pathways of pathogenic attack and is one of the most important causes for mould rot. The manual inspection of apples which are among the wounded or diseased ones requires a lot of manpower and money, and this method not only delays the time of warehousing but also bring the fruit secondary damage. At present, rapid diagnosis of mechinary damages and disease have focused on non-destructive research. Moreover, jasmonic acid (JA) is a key signaling component attracted more and more attention recently.Fuji apples harvested from Baishui basis, apple research centre of NWSUAF were empolyed in this study. Dielectric properties were determined in the fruit with red-dot disease, superficial scald and falling wound from a height of 40 cm and 70 cm onto a smooth marble floor. Wounded fruit were stored at room temperature (20±1℃) for 48 h and the effect of impact injury on physiological-biochemi properties and endogenous signaling components was analyzed by using methodology of grey system theory, physiological-biochemi determination and dielectric parameters measurement with LCR electronic instrument. The general goal of this study were:1) to prove the feasibility of using electrical parameters to evaluate disease and inpact injury.2) to establish the mathematical model for correlating multifactor dynamic changes of apple quality to reveal the physiological-biochemi mechanism and the dielectrical properties of pathogenetic and wounded fruits. This will provide some experimental evidences for elucidating the response mechanism of dielectrical properties of postharvest fruit and modifying the theory of wound-inducible signal transduction. It also establish some theoretical basis for developing new non-destructive method and exploiting new non-destructive inspecting instrument. The results were as follows:1. The relationships among the 14 electrical parameters in Fuji apples stored at room temperature for 48h were investigated. Applying LCR electronic measure instrument, the electrical parameters including impedance (Z), admittance (Y), impedance phase angle (0), static capacitance in series equivalent circuit mode (Cs), static capacitance in parallel equivalent circuit mode (Cp), loss coefficient (D or tanδ), inductance in series equivalent circuit mode (Ls), inductance in parallel equivalent circuit mode (Ls), Q factor (Q), effective resistance in series equivalent circuit mode (Rs), effective resistance in parallel equivalent circuit mode (Rp), conductance (G), reactance (X) and susceptance (B) were determined from 100 Hz to 3.98×106Hz at (20±1)℃. The results indicated the reciprocal of Z equaled to Y and the reciprocal of D equaled approximately to Q (f>398 Hz). Moreover, there were significantly positive correlations among Z, X and Lp. This study revealed that it is enough to detect Z,θ, Cp, D, Rp, G and B in future research.2. The dielectric properties in Fuji apples with red-dot disease stored 70 days at (20±1)℃were investigated. Applying LCR electronic measure instrument, the dielectric properties including Z, Lp and X were determined at 100 Hz,1 kHz,10 kHz,100 kHz and 1 MHz. The results indicated thatε’, Z, X and Lp for all fruits decreased with increasing frequency. Moreover, there were significantly positive correlations among Z, X and Lp, tanδandε’ were significant difference (P＜0.05), but Z, X and Lp were no significance (P>0.05) between diseased and normal fruits from 100 Hz to 1 MHz. Conclusively, tanδandε’can reflect the fruits quality.3. Z, X, G, Cp and D in Fuji apple with superficial scald stored at (20±1)℃were determined from 100Hz to 3.98MHz applying LCR electronic measure instrument. The results showed with increasing frequency, Z and X decreased, Cp and D changed irregularly and G increased in spiral form under same storage times. There was a significantly positive correlation between Z and X and Cp was significant difference (P＜0.01) between diseased and normal fruits from 100Hz to 3.98MHz. In general, Cp was an indicator to pick out diseased fruits.4. The apples fell from a height of 40 cm and 70 cm onto a smoothly marble floor were observed to explore the effects of impact injury on fruit dielectric properties in Fuji apples. The dielectric properties were determined from 100 Hz to 3.98 MHz at (20±1)℃applying LCR electronic measure instrument. There was a significantly negative correlation between Z and B and the absolute value of G is equal to Rp (|G|=Rp). Moreover, Cp and Z were significant difference (P＜0.01) between wounded and sound fruits from 100 Hz to 3.98 MHz at the same stored days. It was concluded that Cp and Z can assess injury status of apples and the optimal frequency was 10 KHz to distinguish wounded and sound fruits.5. The apples fell from a height of 40 cm and 70 cm onto a smoothly marble floor within 48 hours at room temperature were surveyed to investigate the effects of impact injury on fruit quality and activities of protective enzymes in Fuji apples. The results showed that respiration intensity increased significantly, ethylene release rate, O2- production rate and H2O2 content enhanced strongly, the activities of protective enzymes including supiroxide dismutase (SOD), catalase (CAT), peroxidase (POD) and phenylalanine ammonia lyase (PAL) also increased significantly. In Conclusion, impact injury caused membrane-lipid peroxidation of fruits and injury and senescence were induced further. What is more, impact injury can increase the respiration intensity and ethylene release rate and intensify the metabolism of reaction oxidative species (ROS) so that strengthen the induced resistance resulting in promote wound healing and hinder its development in a short time.6. The apples fell from a height of 40 cm and 70 cm onto a smoothly marble floor were explored to investigate the effects of impact injury on endogenous signaling components and activities of lipoxygenase (LOX) in Fuji apples, the contents of JA, salicylic acid (SA), abscisic acid (ABA), nitric oxide (NO), ethylene (Eth) and LOX were detected within 48 hours at room temperature. The results showed that JA content increased significantly, activities of LOX, ethylene production and ABA content enhanced strongly, but NO content decreased. The peak value of JA content preceded the peak value of ABA, and the increasing range of ethylene production was far less than that of JA. The content of bound SA, free SA and total SA decreased sharply and reduced over 70% in a short time. As a result, the highest value of JA contents and the lowest value of free SA contents appeared simultaneously.7. Physicochemical properties and dielectric properties of apples which fell from a height of 70 cm onto a smooth marble floor were determined simultaneously within 48 h and the relationship between them was probed using the methodology of Gray relevancy analysis. Physicochemical property indexes affected diversely dielectric ones. The mathematical model of the dynamic changes of multifactor of apple quality was established using GM (1,6), which can report the effects of various physicochemical property indexes on dielectric ones,. Furthermore, the relationship between dielectric properties and physicochemical properties was uncovered by GM (1,2). It was concluded that TSS can be described by Cp and Rp, TA can be described by Rp. GM (1,1) used to estimate the dynamic change regularity of deg and Cp was established. The feasility of the model was proved by practice test. The results indicated that it was feasible to determine and estimate the fruit quality using electrical parameters, which was significant and useful in both theory and practice.更多还原