杨桃耐寒性初步研究

2001-2002年对从台湾省引进的杨桃品种软枝种、马来种以及我省土种酸杨桃的耐寒性进行了研究,测定其在低温胁迫下的叶片相对电渗率、枝梢浸提液消光度以及叶片束缚水/自由水.结果表明:杨桃忍受低温的临界温度为-2至-3℃,且因品种而异;低温持续时间对临界低温也有影响.土种酸杨桃-3℃处理6h才受冻害,束缚水/自由水也较高,其耐寒性强于软枝种、马来种.     

盐分对碱茅种子发芽影响的机制

耐碱茅种子在盐（NaCl与Na2SO4）及干旱（PEG－6000模拟）胁迫下发芽及其机制的比较研究表明，种子发芽率随溶液渗透势的降低而下降，在等渗条件下三种溶液中的发芽率次序为Na2SO4＞NaCl＞PEG。NaCl与Na2SO4主要通过影响种子吸水量及对膜的毒性影响发芽，根据相关及通径分析结果，其机制为：（1）溶液渗透势及Na+浓度决定的种子吸水对发芽的直接正效应（通径系数0．73）；（2）溶液Na+浓度引起的膜毒性对发芽的直接负效应（－0．51）；（3）种子从溶液中吸收Na使种子吸水增加对发芽的间接正效应（0．30）及使膜毒性增大对发芽的间接负效应（－0．24）。     

玉米作为地质封存CO_2泄漏耐受植物的评估

二氧化碳的捕获与储存(CO2capture and storage,CCS)是全球CO_2减排最重要技术战略,其存在CO_2泄漏的风险,会对周围农田生态产生重要影响。深入认识植物对高浓度CO_2的响应并筛选对CO_2的耐受植物,为CCS项目区农业生产决策提供参考数据。本文设置玉米对不同CO_2浓度的响应情形,选择株高、鲜重、干重、净光合速率、蒸腾速率、气孔导度和胞间CO_2浓度作为玉米耐受的观测指标。结果表明,当CO_2浓度为10 000、20 000μmol/mol时,玉米株高增高7%～12%,生物量增加10%～15%,净光合速率增加高达60%左右;当CO_2浓度为40 000、80 000μmol/mol时,玉米株高度减少9%～12%,生物量减少10%～17%,净光合速率减少35%～45%左右。一定程度CO_2浓度的增加,对玉米生长发育具有"施肥"效应;在更高CO_2浓度下,会抑制其生长发育,并未出现植株死亡的现象。通过CO_2耐受指数法(LCTI)计算得出,玉米可以作为地质封存CO_2泄漏的耐受植物。     

应用Logistic方程确定花椒枝条低温半致死温度

以一年生休眠枝条为材料,对3个品种的花椒进行了电解质外渗率测定,应用Logistic方程建立回归模型;确定半致死温度在-20.20～17.07℃之间,并且抗寒性顺序从小到大依次为油椒、秦安一号、大红袍;相关系数介于0.9541～0.9902之间,表明不同低温和低温持续时间的电解质外渗率遵循Logistic方程的变化规律,且与半致死温度呈线性关系。     

基于稻田控水减排的氮肥运筹试验研究

为改善江汉平原地区稻田水肥管理措施,采用田间小区试验,研究了常规淹灌(CF)和浅灌深蓄(SIDS)条件下,农民习惯施肥(FFP)、30%尿素+70%控释参混肥(30%N+70%CRF)和优化减氮施肥(OPT-N)对水稻各生育阶段稻田氮磷流失特征、养分吸收和土壤养分积累的影响。结果表明:与CF处理相比,SIDS处理田间灌溉水量、总用水量、径流量和渗漏量分别降低41.7%,18.5%,45.8%和21.9%,降雨利用率增加16.2%,TN和TP径流流失量分别降低32.6%~35.9%和36.4%~53.1%,渗漏流失量分别降低22.8%~32.0%和16.2%~33.3%,水稻返青期—拔节孕穗期分别占稻田氮磷径流和渗漏流失总量的70%以上。30%N+70%CRF处理、OPT-N处理较FFP处理,TN径流流失量分别降低19.7%~29.2%,15.1%~25.2%,渗漏流失量分别降低25.4%~51.7%,20.9%~26.4%,TP渗漏流失量分别降低18.4%~24.5%,20.4%~31.6%,但TP径流流失量差别很小。从水稻养分吸收和土壤养分积累来看,SIDS处理实际产量相对CF处理可增产4.4%,但对0—40cm土层氮磷养分累积影响不大,30%N+70%CRF处理和OPT-N处理相对FFP处理可增产5.6%和0.4%,且0—20cm土层速效态氮磷养分能维持在一个较高且相对稳定的水平。综上,浅灌深蓄结合30%N+70%CRF施用有利于稻田节水、减少氮磷流失、水稻增产以及土壤肥力改善。     

油罐加热盘管泄漏回水检测工艺

介绍了一种储油罐加热盘管泄漏锅炉回水检测技术，给出了其在实际应用中的特定工艺规程。检测方法为利用油、水的物性差异，在储罐原有的加热盘管回水管道系统中增设观察玻璃管和分离凹槽，对加热盘管的泄漏及回水带油现象进行检测，该项技术也同样适用于不相容且密度不同的两种液体的分离及定性检测。     

苯甲酸对黄瓜幼苗生理特性的影响

采用不同浓度的苯甲酸对2种两叶一心期的黄瓜幼苗进行处理,研究其对黄瓜幼苗生理特性的影响。结果表明,当浓度为0.5 mmol/L时,增加津杂2号幼苗叶片叶绿素含量;降低密刺王黄瓜幼苗叶片叶绿素含量;在0.25~1.00 mmol/L之间随浓度的升高,津杂2号和密刺王黄瓜幼苗叶片类葫萝卜素的含量、硝态氮含量、硝酸还原酶活性均不断降低,电解质外渗率均不断增加,津杂2号幼苗的变化趋势弱于密刺王黄瓜,这表明津杂2号较密刺王黄瓜耐一定程度的苯甲酸。     

Exogenous application of humic acid and salicylic acid to alleviate seedling drought stress in two corn (Zea mays L.) hybrids

Efficacy of 1?mM humic (HA) and salicylic (SC) acids on SC 260 and SC 705 corn seedlings to alleviate drought stress via polyethylene glycol was studied via hydroponics at Shiraz University, Iran in a factorial, randomized design, with four replicates each. Under stress, SC 260 had higher electrolyte leakage compared to SC 705, and exogenous application of HA combined with SA decreased SC 705 electrolyte leakage. As a general trend, photosynthetic pigment content, relative water content, root and shoot length, mean number and diameter of central and peripheral root metaxylem, and K⁺ accumulation were higher in SC 705 treated with HA and SA compared to SC 260. Application of HA with SA could be an effective and low cost approach to ensure seedling establishment and plant growth in fields affected by soil drought in the early season, especially for the SC 705 corn hybrid in semi-arid regions.     

Silicon-induced changes in growth,ionic composition,water relations,chlorophyll contents and membrane permeability in two salt-stressed wheat genotypes

We investigated the effect of exogenously applied silicon (Si) on the growth and physiological attributes of wheat grown under sodium chloride salinity stress in two independent experiments. In the first experiment, two wheat genotypes SARC-3 (salt tolerant) and Auqab 2000 (salt sensitive) were grown in nutrient solution containing 0 and 100 mM sodium chloride supplemented with 2 mM Si or not. Salinity stress substantially reduced shoot and root dry matter in both genotypes; nonetheless, reduction in shoot dry weight was (2.6-fold) lower in SARC-3 than in Auqab 2000 (5-fold). Application of Si increased shoot and root dry weight and plant water contents in both normal and saline conditions. Shoot Na⁺ and Na⁺:K⁺ ratio also decreased with Si application under stress conditions. In the second experiment, both genotypes were grown in normal nutrient solution with and without 2 mM Si. After 12 days, seedlings were transferred to 1-l plastic pots and 150 mM sodium chloride salinity stress was imposed for 10 days to all pots. Shoot growth, chlorophyll content and membrane permeability were improved by Si application. Improved growth of salt-stressed wheat by Si application was mainly attributed to improved plant water contents in shoots, chlorophyll content, decreased Na⁺ and increased K⁺ concentrations in shoots as well as maintained membrane permeability.     

超氧化物歧化酶在苜蓿抗寒锻炼过程中的作用

对苜蓿Medicago sativa抗寒锻炼过程中膜透性和超氧化物歧化酶(SOD)活性进行测定,通过苜蓿组织冰冻半致死温度(LT50)说明在抗寒锻炼过程中苜蓿抗寒性的变化。结果表明,在不同低温处理下,苜蓿叶片和根茎组织电解质透出率呈现出S型曲线变化。抗寒锻炼过程中,苜蓿组织LT50从9月初的-6.9℃下降到11月初的-15.6℃,下降了8.7℃。随着秋季气温的下降,苜蓿叶片SOD活性显著增加,11月上旬达到最高峰,此后显著下降。这说明SOD在抗寒锻炼过程中起着重要的保护作用,当苜蓿获得抗寒能力后,SOD活性逐渐下降。在抗寒锻炼过程中,苜蓿根茎SOD活性的变化与叶片中SOD活性的变化规律不一致,苜蓿根茎中SOD活性水平显著高于叶片中的SOD活性水平。聚丙烯酰胺凝胶电泳分析结果显示,不同苜蓿品种具有6条共同的SOD同工酶酶带。适应高寒地区气候条件的当地材料同德杂种苜蓿表现出与其他苜蓿品种较大的特异性。抑制试验表明苜蓿SOD为CuZn-SOD。