外源性植物生长激素对猕猴桃果实光学特性的影响机理解析

Abusing exogenous plant growth regulator (EPGR for short) is the main reason that causes the kiwifruits have poor quality and soften quickly, and causes big economic loss during kiwifruit storage. Moreover, the safety problem caused by using EPGR for fruits and vegetables has become a focus for concern. Our previous studies have shown that spectroscopy technology can be used to non-destructively detect the kiwifruits treated with EPGR. However, the influence mechanism of EPGR on optical properties of fruits is not clear. Therefore, the widely planted varieties of kiwifruits in China (Hayward, Huayou, and Hongyang) will be used as the samples, and N-(2-chloro-4-pyridyl)-N'-phenylurea will be used as EPGR to treat kiwifruits. The influence rules of EPGR on the main chemical compositions (such as total sugar content, glucose, sucrose, fructose, total acid content, and water content), and on the color, ultrastructures (cells, sub-cells, etc), optical absorption and scattering properties of peel and flesh will be analyzed. The influence mechanisms of EPGR on optical absorption and scattering properties will be revealed based on chemical and physical characteristics and ultrastructures. The better spectra detection method which can be used to identify EPGR treated kiwifruits precisely will be determined, and the "fingerprint" wavelengths or wavebands which could represent the characteristics of kiwifruits treated with EPGR will be found. The research achievements of the study will enrich the optical properties of fruits, and will provide necessary theoretical support for developing detectors on fruits and vegetables treated with EPGR.

外源性植物生长激素(膨大剂)的滥用是导致我国猕猴桃品质差、不耐贮藏、库存损失严重的主要问题，而施用膨大剂引起的果蔬安全问题已成为人们关注的热点。前期研究表明，光谱技术可以无损检测施用膨大剂的猕猴桃(膨大果)，而膨大剂对果实光学特性的影响机理尚不清楚。为此，本项目以我国主栽的多品种猕猴桃(海沃德、华优和红阳)为对象，以氯吡脲为膨大剂，研究膨大剂对生长、成熟和釆后后熟过程中猕猴桃果实的主要化学成分(总糖、葡萄糖、蔗糖、果糖、总酸、含水率)以及果皮和果肉的颜色、组织超微结构(细胞、亚细胞等)、光吸收特性和光散射特性的影响规律；从理化特性和组织超微结构角度解析膨大剂对猕猴桃果实光吸收特性和散射特性的影响机理；确定检测猕猴桃膨大果的最佳光谱采集方式；发现表征多品种猕猴桃膨大果的“指纹”波长或波段。本项目的研究成果一方面将丰富果实的光学特性理论，另一方面将为膨大果蔬检测仪的研发提供必要的理论支撑。

施用外源性植物生长激素(膨大剂)引起的果蔬安全问题已成为人们关注的热点。光谱技术虽可以无损检测施用膨大剂的猕猴桃(膨大果)，但膨大果与正常果之间光学特性的差异及差异机理尚不清楚。为此，本项目以我国主栽的‘海沃德’、‘徐香’和‘华优’为对象，以氯吡脲为膨大剂，研究了不同浓度膨大剂处理对生长、成熟和釆后后熟过程中猕猴桃果实的主要理化特性(可溶性固形物含量SSC、含水率、硬度等)、果肉组织结构、光学特性(吸收系数μa和约化散射系数μ's)的影响规律；从理化特性和组织结构角度解析了膨大果与正常果光学特性的差异性机理；确定了检测猕猴桃膨大果的最佳光谱采集方式，提取了表征多品种猕猴桃膨大果的“指纹”波长，基于多光谱技术开发了便携式猕猴桃膨大果检测仪；提出了基于猕猴桃大小以及果萼形状识别猕猴桃膨大果的方法，并开发了基于Android平台的猕猴桃膨大果检测APP。.结果指出，(1)同一生长/成熟期，吸收峰(970nm、1190nm和1390nm)处经不同浓度膨大剂处理的猕猴桃果肉的μa均大于正常果。1190nm下，膨大果与正常果果肉的μ's普遍有显著性差异，且膨大果果皮的μ's大于正常果。膨大果比正常果有更高的SSC和含水率，更低的硬度以及更大的果肉细胞。光学参数与理化参数的相关性因波长而异。970nm和1190nm下，果肉μa和1190nm的μ's与SSC及小细胞面积呈正相关，与含水率和硬度呈负相关，而1390nm下果肉的μa与各理化参数的相关性相反。(2)釆后后熟期间，高浓度处理下果肉的μa和μ's大于低浓度处理，但对于μa而言，差异不显著。970nm下果肉μa与SSC和硬度有很强的相关性。μa和μ's具有识别猕猴桃膨大果以及不同处理浓度的潜力。(3)漫反射是采集猕猴桃光谱的最佳方式，对于三种猕猴桃提取了6-7个特征波长。开发的猕猴桃膨大果检测仪对膨大果有良好的识别率。(4)开发的APP对三种猕猴桃膨大果的识别率分别为91.5%、87.5%和97.5%。.本项目的研究成果一方面丰富了果实的光学特性理论，另一方面为其他膨大果蔬检测仪的研发提供了理论基础。