水分胁迫下四种滨藜属植物保护酶活性的变化

在水分胁迫下,对4种滨藜属(AtriplexL.)植物的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、丙二醛含量(MDA)进行了测定.结果表明:水分胁迫10~20 d,4种滨藜的SOD、CAT、POD活性呈上升趋势;而水分胁迫20~30 d,SOD、CAT、POD活性开始呈现下降趋势.4种滨藜MDA含量均随胁迫时间延长而逐步增加,A.ca-nescens和A.obovataMDA含量较低,且增加幅度小;而A.gardneri和A.lentiformisMDA含量较高,且增加幅度较大.     

NaCl在四翅滨藜适应渗透胁迫中的作用

泌盐盐生植物四翅滨藜是一种多年生C₄灌木,具有良好的适应盐碱和干旱环境的能力。前期研究发现,通过将过量Na⁺转运至叶表面盐囊泡、增加Na⁺对渗透势的贡献以提高植株保水能力是四翅滨藜耐盐的主要策略,且100 mmol·L^-1 NaCl可显著刺激其生长。为进一步探究NaCl是否有助于缓解渗透胁迫对四翅滨藜生长的不利影响,本研究分别用不含和含有100 mmol·L^-1 NaCl的山梨醇引起的总渗透势为-0.2和-0.5 MPa的1/2 Hoagland营养液处理5周龄四翅滨藜幼苗5 d。结果表明,在渗透胁迫下,NaCl的添加可增加叶片相对含水量、提高净光合速率以及降低叶渗透势(Ψ_s),从而促进四翅滨藜的生长。NaCl的添加还显著增加了茎叶组织及叶盐囊泡中的Na⁺积累并提高了Na⁺对叶Ψ_s的贡献,且对茎叶组织中K⁺含量影响较小。此外,渗透胁迫下,添加一定浓度NaCl显著增加了植株中游离脯氨酸和甜菜碱含量,它们除作为保护剂减轻渗透胁迫损伤外,还参与植株的渗透调节,从而进一步提高四翅滨藜对渗透胁迫的适应性。综上所述,适宜浓度的NaCl的确能够有效缓解渗透胁迫对四翅滨藜生长的不利影响。     

遥感环境综合技术系统在草地资源动态监测与管理中的应用研究──以新疆阜康县为例

本研究利用１９９１～１９９３年在新疆阜康县不同草地类型上观测到的牧草产量、环境资料与地面光谱、气象卫星资料等，进行了多重相关分析。结果表明，不同类型的草地产量与环境因子和各种绿度值间存在着显著相关性（Ｐ＜０．０５），相关系数（ｒ）均达到０．８４以上，并通过Ｆ检验。又利用作者研制开发的遥感环境综合技术系统（ＲＳＥＣＴＳ）进行了草地资源的系列动态监测与分析，建立了地学、光学、卫星遥感和综合估产模型及相应的可利用牧草估产模型等，估产精度可达９０％以上；在草地产量预报中，成功地导入投影寻踪回归（ＰＰＲ）技术，建立了牧草产量预报模型，提高了产量预报的精度与效能；并运用以上优化模型进行了实际产量预报，总体精度达到７５％以上，求得了冬季枯草产量换算系数和牧草产量年变率。同时，进一步运用ＲＳＥＣＴＳ建立了草地利用和草畜平衡监测模式及进行了草畜平衡与管理诸方面分析和论证，基本实现了从初级生产到次级生产对草地资源的遥感动态监测，解决了许多有关技术性难题，找出草畜系统管理中存在的主要问题，制定了调控措施，为草地资源的科学管理与合理利用，提供了坚实依据和可靠方法。关键词     

Effects of Calcium Chloride on Growth,Membrane Permeability and Root Hydraulic Conductivity in Two Atriplex Species Grown at High (Sodium Chloride) Salinity

Calcium (Ca) has an important role in plant physiology, including involvement in the responses to salt stress, and controls numerous processes. To overcome the negative impact of high salinity, the addition of supplemental Ca to the growth medium as an ameliorative agent could be necessary. Atriplex halimus subsp. schweinfurthii and Atriplex canescens subsp. linearis were grown in hydroponic conditions to investigate the effectiveness of supplementary calcium chloride (CaCl₂) applied into nutrient solution on plants grown at high (400 mM) sodium chloride (NaCl) concentration. Treatments were: 1) nutrient solution alone [control (C)]; 2) nutrient solution plus 400 mM sodium chloride (NaCl); and 3) nutrient solution and 400 mM NaCl plus supplementary 40 mM CaCl₂ supplied in nutrient solution (NaCl + CaCl₂). The experiment was set up as a completely randomized design, consisting of two species (A. halimus and A. canescens), three treatments (control, NaCl, and NaCl + CaCl₂), and five replicates. Dry weight and chlorophyll content of plants grown at high NaCl were lower than those at normal nutrient solution. Supplementary CaCl₂ ameliorated the negative effects of salinity on plant growth in both species. Root hydraulic conductivity (L ₀) decreased with elevated NaCl and increased with supplementary CaCl₂ compared to the stressed plants. Membrane permeability increased with high NaCl application and these increases in root membrane permeability decreased with supplementary CaCl₂ compared to the NaCl treatment. Sodium (Na) concentration in plant tissues increased in both species in high NaCl level. Application of supplementary CaCl₂ lowered Na concentration. Concentrations of calcium (Ca) and potassium (K) were at deficient ranges in the plants grown at high NaCl levels and these deficiencies were corrected by supplementary CaCl₂.     

不同刈割频率对四翅滨藜当年生产性能的影响

进行了四翅滨藜全年刈割1次、2次、3次和4次饲草生产对比试验。结果表明,四翅滨藜年刈割2次、3次可以获得较高的鲜草产量,单株鲜草产量分别为2713.2和2458.7g,年刈割2次鲜草产量是年刈割1次、4次的2.3倍和1.5倍。年刈割2次、3次的干草产量也较高,尤其以年刈割2次最高,单株干草产量可达1148.5g。随着刈割频率的增加,鲜干比不断上升,为年刈割4次>年刈割3次>年刈割2次>年刈割1次。     

播种密度和氮肥运筹对三角叶滨藜生长与品质的影响

以三角叶滨藜为材料,研究了播种密度及氮肥对三角叶滨藜生长、鲜叶产量及品质的影响.结果表明:①3.75(B1)、7.5(B2) kg·hm-2的播种量,100(N2)、200( N3) kg·hm-2的施氮量均可以显著提高三角叶滨藜的株高及鲜菜产量.7.5(B2) kg·hm-2的播种量,200(N3)kg·hm-2施氮量较有利于三角叶滨藜鲜菜总产量的增加.②100(N2) -200 (N3 )kg·hm-2范围内的氮肥能显著提高三角叶滨藜Vc及蛋白含量.15(B4) kg· hm-2的播种量不利于三角叶滨藜品质的积累,Vc及蛋白含量显著下降.     

3种滨藜属植物幼苗叶片对NaCl胁迫的生理响应

以灰白滨藜变种1、灰白滨藜变种2和四翅滨藜的1年生实生幼苗为试验材料,采用沙土盆栽试验,对不同质量浓度(0、0.1%、0.3%、0.5%、0.7%和1.0%)NaCl单盐胁迫条件下3种滨藜属植物幼苗叶片盐害指数、耐盐阈值及生理特性等指标进行了测定。结果表明:盐胁迫提高了3种滨藜属植物幼苗各器官Na+浓度,降低了K+浓度,灰白滨藜变种2较其他2种植物各器官保持了相对较低的Na+和较高K+浓度,有利于维持较高的K+/Na+平衡;随着土壤盐浓度的增加,灰白滨藜变种2叶片受盐害起始浓度、耐盐阈值及耐盐极限浓度均高于灰白滨藜变种1和四翅滨藜,最终确定出灰白滨藜变种1、灰白滨藜变种2和四翅滨藜的耐盐阈值分别为0.59%、0.68%和0.63%;叶片丙二醛含量、细胞膜相对透性随着盐胁迫程度的加剧而增加。经隶属函数综合评价认为3种滨藜属植物耐盐性强弱顺序依次为:灰白滨藜变种2(0.686)＞四翅滨藜(0.532)＞灰白滨藜变种1(0.102);与灰白滨藜变种1相比,灰白滨藜变种2和四翅滨藜各项生理指标特征对盐土环境的适应能力更强。      

四翅滨藜的生物-生态学特性及研究进展

系统介绍了四翅滨藜Airiplex canescens的生物-生态学特性、更新过程、牧草价值,及其对土壤、植被的影响,回顾了四翅滨藜作为饲料对牲畜、鸟类和小哺乳类动物的作用以及在增加牧草产量、促进植被向恢复演替方向发展和丰富植物群落多样性方面的作用.     

Na2SO4胁迫对鞑靼滨藜氮同化作用的影响

在室外水培条件下，随Ｎａ２ＳＯ４胁迫浓度的升高及胁迫时间的延长，鞑靼滨藜叶生长速率，硝酸还原酶活性和全氮含量均呈下降趋势，游离氨基酸含量呈上升趋势。由实验结果可以看出，盐胁迫下硝酸还原活性的迅速下降是植物减少有害含氮化合物的积累和减少能量损耗的重要适应性反应。     

Silvopastoral systems in arid and semiarid zones of northern Chile

The main silvopastoral systems carried out in arid and semiarid zones of northern Chile are presented. Plantations with queñoa (Polylepis besseri) in the Precordillera (3,000–4,000 meters above sea level) and with ‘queñoa de altura’ (Polylepis tarapacana) in the High Plateau (over 4,000 m.a.s.l.) are described. For extremely arid zones (2 mm/yr), tamarugo (Prosopis tamarugo) and algarrobo (Prosopis chilensis) plantations in Pampa del Tamarugal are reviewed. In this zone 20,483 ha have been planted, 88% with P. tamarugo. These plantations feed a variable herd of 7,000–9,000 sheep and goats per yr. The forage produced per tree varies from 20 to 70 kg/yr for 14 to 22 yr old trees, planted in densities of 100/ha. For the semiarid zone, plantations with forage shrubs of the genus Atriplex are described. Between 1975 and 1989, about 37,000 ha were planted in the coastal zone of Coquimbo region, 60% of them with A. nummularia and the rest with A. repanda. Productivity varies widely in both species. It depends on management techniques and environmental variables. Afforestation with such species offers green forage during periods of scarcity of natural grasses, especially during long droughts. The rate of afforestation is declining because the government has stopped planting, and the private sector is planting less than expected. This is because often yields have been low, due to either natural causes or deficient management.