暗诱导油菜子叶衰老过程G-6-P脱氢酶和乙醇脱氢酶活性的变化

以离体油菜子叶为材料，研究了暗诱导子叶衰老过程中G-6-P脱氢酶(G6PDH)和乙醇脱氢酶(ADH)活性的变化。结果表明在暗诱导衰老过程中，2种酶的活性均呈急速下降的趋势。暗诱导ld G6PDH活性下降了40％以上，第4d活性下降了80％以上。G6PDH活性的下降可能是导致植物细胞衰老过程中活性氧水平上升的因素之一，磷酸戊糖途径(PPP)活性的调节可能在诱导植物细胞的衰老中有重要作用。ADH在正常油菜子叶中维持有一定的活性，但在暗诱导离体子叶衰老过程中，ADH活性迅速下降，暗诱导ld活性下降了40％以上，第3d活性下降了60％以上。推测ADH活性变化可能对于衰老的诱导和加剧有重要意义。     

下层土壤容重对玉米生育后期叶片衰老的生理效应

采用桶栽法研究了下层土壤容重对玉米生育后期叶片衰老的生理效应。结果表明,随着下层土壤容重的增加,玉米单株叶面积下降;容重越大,叶面积指数下降幅度越大,玉米生育后期叶片衰老速度越快,SOD酶活性降低越多,MDA含量增加越多。     

遮光对不同基因型玉米叶片衰老和产量的影响

采用盆栽试验,研究了遮光对不同基因型玉米叶片衰老和产量的影响。结果表明,苗期遮光和穗期遮光均使玉米叶面积指数L(AI)降低,但粒期遮光则使玉米生育后期LAI下降减缓。遮光条件下生长的玉米叶片SOD酶活性升高,MDA含量降低。不同时期遮光处理均可导致玉米减产,减产程度为粒遮>穗遮>苗遮。除千粒重和穗粗外,遮光处理对其它穗部性状指标的效应值均达极显著水平。遮光对玉米叶片衰老和产量的效应在不同基因型之间表现出明显差异。     

小麦氮素营养与后期衰老关系的研究

本文研究了不同生育时期追施氮肥与超高产小麦后期衰老的关系。结果表明,在不同处理中,中后期适量追肥可明显抑制叶绿素的降解,并使植株体内保持高水平的保护酶活性,降低后期细菌膜脂过氧化水平,从而在一定程度上延结功能叶片的衰老,有利于籽粒灌浆,提高产量。     

赞皇大枣采后成熟衰老期生理生化变化

以 2种成熟度 (全红和半红 )的赞皇大枣为试材 ,研究了采后常温下贮藏时果实的生理生化变化。结果表明 ,果实的褐变度、SOD活性、MDA和糖的含量随贮藏期的延长而增加 ,与半红果相比 ,全红果的褐变度、MDA和糖的含量较高 ,SOD活性差异较小 ;贮藏前期 ,全红果的POD和PPO活性、蛋白质和总酚含量高于半红果 ,而在贮藏后期又低于半红果。     

灌浆期干旱对小麦旗叶衰老和籽粒产量的影响

在高肥条件下,研究灌浆期干旱对两个抗旱性不同的旱地小麦品种旗叶衰老和籽粒产量的影响。结果表明,豫麦２号抗旱系数为０．９０麦现为旗叶叶绿素下降快,ＭＤＡ增加快,活性氧代谢失调出现的早;     

1-Methylcyclopropene (1-MCP)-induced protein expression associated with changes in Tsai Tai (Brassica chinensis) leaves during low temperature storage

Leaf yellowing is an early symptom of senescence and greatly affects the commercial value of leafy vegetable products. The ethylene action inhibitor 1-methylcyclopropene (1-MCP) has been widely studied regarding its effects on senescence, but little is known on how it influences the protein expression profile of leafy vegetables in storage. In this study, by using a proteomic approach, changes in proteomic profile induced by 1-MCP in Tsai Tai (Brassica chinensis) leaves during storage under low but non-freezing temperature were investigated. Compared with the control, 1-MCP treatment inhibited leaf etiolation and reduced weight loss of Tsai Tai stored at 1 °C, indicating that it delayed senescence. Two dimensional electrophoresis revealed 16 differentially accumulated protein spots, 12 of which were successfully identified by mass spectrometry. A comparison between the control and the 1-MCP-treated Tsai Tai showed that 1-MCP enhanced levels of four proteins involved in photosynthesis, i.e. photosystem II protein, oxygen-evolving enhancer protein 2, chloroplast ribulose 1,5-bisphosphate carboxylase/oxygenase activase and high molecular weight RuBisCO, inhibited malate dehydrogenase, a key enzyme involved in the tricarboxylic acid cycle, downregulated gibberellin 2-beta-dioxygenase expression, a key enzyme involved in biosynthesis of active gibberellins, and suppressed glutathione s-transferase, an important scavenger for reactive oxygen species. These results imply that 1-MCP could maintain leaf capacity for carbon assimilation, inhibit the tricarboxylic acid cycle, induce biosynthesis of GAs and reduce levels of reactive oxygen species, which together may have contributed to inhibition of leaf yellowing and delay of senescence.     

阻止授粉诱导玉米衰老提前启动现象的研究

利用豫816等8个玉米骨干自交系为材料,对授粉与未授粉处理自交系导致玉米衰老表型症状和叶片叶绿素含量变化以及衰老相关基因表达比较分析。结果表明,阻止授粉植株叶片与授粉对照相比,豫816和B73自交系表现出衰老提前启动的显著症状,启动衰老提前了17 d,说明阻止授粉对衰老启动具有明显诱导作用;郑58等6个自交系的阻止授粉与授粉对照植株叶片均为绿色,没有衰老症状的出现,说明阻止授粉不具有诱导衰老的作用。诱导衰老植株不同子粒结实率与启动衰老提前的天数密切相关,结实率为0~15%的未授粉植株具有启动衰老提早的诱导作用,结实率达到35%以上的植株则不具有启动衰老提早的诱导作用。6个玉米衰老相关基因差异表达的趋势与衰老表型症状变化趋势基本一致,存在1个基因差异表达与表型衰老症状呈现的时间窗口,可能参与了诱导玉米衰老的启动。     

Pre-harvest calcium application increases biomass and delays senescence of broccoli microgreens

Microgreen consumption has been steadily increasing in recent years due to consumer awareness of their unique color, rich flavor, and concentrated bioactive compounds. However, industrial production and marketing is limited by their short shelf-life associated with rapid deterioration in product quality. This study investigated the effect of pre-harvest calcium application on the post-harvest quality and shelf-life of broccoli microgreens. Broccoli microgreen seedlings were sprayed daily with calcium chloride at concentrations of 1, 10 and 20 mM, or water (control) for 10 days. The fresh-cut microgreens were packaged in sealed polyethylene film bags. Package headspace atmospheric conditions, overall visual quality and tissue membrane integrity were evaluated on days 0, 7, 14, and 21, during 5 °C storage. Results indicated that the 10 mM calcium chloride treatment increased the biomass by more than 50%, and tripled the calcium content as compared to the water-treated controls. Microgreens treated with 10 mM calcium chloride spray exhibited higher superoxide dismutase and peroxidase activities, lower tissue electrolyte leakage, improved overall visual quality, and reduced microbial growth during storage. Furthermore, calcium treatment significantly affected expression of the senescence-associated genes BoSAG12, BoGPX6, BoCAT3 and BoSAG12. These results provide important information for commercial growers to enhance productivity and improve postharvest quality and shelf-life, potentially enabling a broadening of the retail marketing of broccoli microgreens.