Rice (Oryza sativa L.) roots were fed with L-ascorbic acid (AsA) and its putative precursors to observeAsA and oxalate concentrations and the resistance of rice to chilling, water stress, and Al toxicity. AsA concentration was significantly enhanced in both shoots and roots of rice seedlings by feeding with D-glucose or L-galactono-c-lactone. AsA or L-galactono-c-lactone treatment increased accumulation of oxalate mainly in soluble form, while these treatments decreased electrolyte leakage from root cells, H2O2 and lipid peroxidation level in rice seedlings subjected to chilling, water stress, and Al toxicity. They also alleviated the inhibition on root growth by Al. These results indicated that AsA and its immediate precursor protected plants against the oxidative damages induced by various stresses. However, 0.5 mM AsA and 10 mM L-galactono-c-lactone treatment had no significant effect on superoxide dismutase and catalase activity and ascorbate-peroxidase activities. Enhanced Al resistance caused by AsA and L-galactono-c-lactone may possibly be resulted from increased level of oxalate, which acts as metal chelator. Thus it is proposed that manipulation of AsA and oxalate biosynthesis through enhancement of L-galactono-c-lactone level in plants could be a strategy for improving abiotic stress tolerance.

Abscisic acid (ABA) regulates plant adaptive responses to various environmental stresses. 9-cis-epoxycarotenoid dioxygenase (NCED) is the key enzyme of ABA biosynthesis in higher plants. A NCED gene, SgNCED1, was overexpressed in transgenic tobacco plants which resulted in 51–77% more accumulation of ABA in leaves. Transgenic tobacco plants decreased stomatal conductance, transpiration rate, and photosynthetic rate but induced activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate-peroxidase (APX). Hydrogen peroxide (H2O2) and nitric oxide (NO) in leaves were also induced in the transgenic plants. Compared to the wild-type control, the transgenic plants improved growth under 0.1 M mannitol-induced drought stress and 0.1 M NaClinduced salinity stress. It is suggested that the ABAinduced H2O2 and NO generation upregulates the stomatal closure and antioxidant enzymes, and therefore increases drought and salinity tolerance in the transgenic plants.

为了建立近红外光谱测定茶叶中茶多酚和茶多糖的模型，应用了人工神经网络方法，选择了7432.3～6155.7 cm-1和5484.6～4192.5cm-1特征光谱范围，以网络结构参数的输入层、隐层、输出层神经元数目分别为（8，4，1）和（7，5，1）来建立茶多酚和茶多糖的测定模型，模型的结果表明建模的茶多酚和茶多糖的r,RMSECV,RSECV别为0.9847，0.460，0.123和0.947O，0.136，0.224；预测集的r，RMESP，R5EP则分别为0.9804，0.529，0.017和0.9682，0.111，0.030。由此说明建立的近红外光谱人工神经网络模型可用于预测茶叶中茶多酚和茶多糖的含量。

Previous studies suggest that abscisic acid (ABA) stimulates the activities of antioxidant enzymes under normal and chilling temperature and enhanced chilling resistance in Stylosanthes guianensis. The objective of this study was to test whether nitric oxide (NO) is involved in the ABA-induced activities of the antioxidant enzymes in Stylosanthes guianensis due to its nature as a second messenger in stress responses. Plants were treated with NO donors, ABA, ABA in combination with NO scavengers or the nitric oxide synthase (NOS) inhibitor and their effects on the activity of antioxidant enzymes and NO production were compared. The results showed that ABA increased the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). The effect of ABA on antioxidant enzyme activities was suppressed by the NOS inhibitor, Nx-nitro-L-arginine (L-NNA), and the NO scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl3-oxide (PTIO). NO content increased after 5 h of ABA treatment. The NO-scavenger, PTIO, and the NOS-inhibitor, L-NNA, inhibited the accumulation of NO in ABA-treated Stylosanthes guianensis. NO donor treatment enhanced the activities of SOD, CAT, and APX. The results suggested that NO was involved in the ABA-induced activities of SOD, CAT, and APX in Stylosanthes guianensis. ABA triggered NO production that may lead to the stimulation of antioxidant enzyme activities.

测定了低温下水稻（Orfza soAiva L）品种湘糯1号（耐冷品种）和I]R50（冷敏感品种）光台碳同化过程的关键酶二磷酸核酮糖羧化酶（RuBPCase）/加氧酶（RuBPOase）、果糖-1，6-二磷酸酯酶（FBPase）以及糖代谢的蔗糖台酶（SS）和蔗糖磷酸台酶（SPS）活性和可溶性糖含量的变化。耐冷品种的RuBPCase, RuBPOase和羧化/加氧比以FBPase活性受低温影响较小，而冷敏感品种的这些参数在低温下降低。两品种的SS和SPS活性低温下均提高，且耐冷品种的酶活性高于冷敏感品种。低温下2个品种的可溶性糖含量变化与SS和SPS活性的变化类似。水稻不同耐冷品种低温下碳代谢酶活性变化与其耐冷性相一致。

对来源于日本、韩国和美国的42个大花蕙兰品种和两个国产兰属原生种进行了遗传多样性和亲缘关系的AFLP分析，9对多态性引物在50～500 bp内共扩增出l597条带，其中多态性带l565条，多态性比率98.0％。单引物对扩增的带数156～193条，平均每对引物扩增带数177条。42个品种具特征带或缺失带。大花蕙兰品种司的遗传多样性丰富，品种司的相似系数0.3399～0.8223，平均相似系数0.5783。UPGMA聚类结果将供试品种分为4大类，与根据花枝类型或花径大小、花色等形态指标分类的结果相吻台，同一产地来源甚至同一育种公司选育出的品种能基本上聚类在一起，反映出了品种司的亲缘关系。

以不同磷水平的营养液培养水稻幼苗，比较研究了低温处理后耐冷性不同品种光台特性的变化。低温下2个品种的水稻叶片的叶绿素含量、光台速率、Fv/Fm和qp均降低，冷敏感品种比耐冷品种的降低幅度更大。与缺磷和正常磷水平培养的材料相比，高磷培养的材料在低温下具有较高的叶绿素含量、光台速率、Fv/Fm和qp缺磷培养的材料在低温下叶绿素含量、光台速率、Fv/Fm和qp下降加剧，耐冷品种的NPQ升高，但冷敏感品种的NPQ变化不大。磷营养水平对冷敏感品种光合作用的影响比对耐冷品种更明显，通过体外施磷，可以提高水稻的耐冷性。

奉研究应用分光光度法和高效液相色谱法测定了4种不同茶叶的化学成分和儿萘素的含量．结果表明，茶叶品种不同，其化学成分、儿茶素的组成与配比差异较大，这是头定其抗癌作用的物质基础。

为探讨热带和温带牧草对温度胁迫抗性差异的生理机制，本文比较研究了柱花草（Stylosanthes guianensis）和苜稽（Medicago sativa）叶片抗氧化系统、可溶性糖和叶绿素荧光参数的季节性变化。结果表明：拄花草在冬季内二醛（MDA）含量升高，西式苜蓿MDA含量在夏季升高；柱花草超氧化物歧化酶（SOD）活性在越冬前和越夏前升高，苜蓿SOD活性在秋冬季较高，春夏季较低；柱花草和苜蓿的过氧化氢酶（CAT）活性在越冬前均升高，但柱花草春夏季维持稳定，苜蓿CALR活性夏季升高；柱花草抗坏血酸一过氧化物酶（APX）活性全年较稳定，苜蓿的APx活性在春夏季不断升高；柱花草抗坏血酸（ASA）和还原型谷胱甘肽（（GSH）古量在越冬前、后均升高，而苜蓿只在越冬前升高，越冬后维持稳定水平；柱花草和苜蓿的可溶性糖含量在越冬前均积累，柱花草积累高峰出现得较晚，且在越冬后再次大量积累，苜蓿在越冬前就大量积累，更有利于提高抗寒性；柱花草光系统Ⅱ（PSⅡ）最大光化学效率（Fv/Fm）和非光化学荧光粹灭（NPQ）在冬季有一定程度降低，PsⅡ光化学量子效率（φFSⅡ）和光化学荧光猝灭（qP）等叶绿素荧光参数明显降低，苗蓿Fv／Fm、φFSⅡ和qP等参数较稳定．但NPQ在春夏季不断降低。这说明，柱花草和苜蓿抗寒和抗热性的不同与其抗氧化系统、可溶性糖和PsⅡ季节件变化的差异有关。