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11.
西北干旱灾害及其气候趋势研究 总被引:10,自引:4,他引:10
刘引鸽 《干旱区资源与环境》2003,17(4):113-116
利用西北五省1950~2000年降水、温度和农作物旱灾面积资料,用降水的Z指标法,农作物受旱成灾率确定了西北干旱指标和旱灾等级,分析了西北旱灾特征及气候变化趋势。表明西北农业旱灾以70、90年代最严重,而且呈增加趋势,气温在升高,降水在减少。根据预测21世纪前十年西北干旱有所减轻。 相似文献
12.
关中西部四灌区旱情规律分析 总被引:1,自引:0,他引:1
为给关中西部灌区水资源合理调控提供依据,在简述干旱及其分类的基础上,指出了关中西部各类干旱多源于气象干旱。对该区7个气象站的年降水进行分析表明,各气象站年降水量的变差系数均为0.25,偏态系数均为0.5。以兴平气象站作为代表站对不同历时的旱情进行了分析,结果显示11月到来年2月发生重旱和特旱的概率较大,在30%左右,特别是12月份,概率达54%,且以特旱为主;7、8月份以中旱和重旱为主;夏玉米播前发生特旱的概率较高,达27%,拔节孕穗和抽穗开花期以特旱为主,概率达33%;冬小麦的越冬和麦黄期以特旱为主,发生概率在30%左右。 相似文献
13.
灰色灾变理论在宁南山区干旱气候预测中的应用 总被引:15,自引:2,他引:15
在分析宁南山区干旱气候特征及其对农业生产影响的基础上 ,借助灰色灾变理论分别建立了春旱、夏旱、秋旱、春夏连旱、夏秋连旱、全年旱等六种干旱类型的 GM( 1 ,1 )预测模型 ,并对 2 0 0 0~ 2 0 2 0年的干旱气候做出预测。经对 2 0 0 0年和 2 0 0 1年预测结果验证 ,吻合性良好。此外 ,提出了宁南山区抗旱防旱的综合农业措施。研究结果可对广大旱区抗旱减灾 ,促进农业生产发展提供科学指导。 相似文献
14.
The influence of rain and drought before, and air temperature during, weed control with hot water was studied in laboratory experiments on the test weed Sinapis alba (white mustard). The plants were grown in a greenhouse and treated outdoors. There was no difference in weed control effect when S. alba plants at the four‐leaf stage were treated at the air temperatures 7°C and 18°C. The effective energy dose for a 90% fresh weight reduction was 465 kJ m?2 for both air temperatures. Weed control of S. alba at the four‐ to six‐leaf stage in rainfall above the rainwater run‐off level increased the required effective energy dose by 20% (i.e. 120 kJ m?2) compared with dry plants. A short period of drought just before treatment on S. alba at the two‐ to four‐leaf stage increased the plant fresh weight reduction, which was 22% at low energy dose (190 kJ m?2) and 44% at high energy dose (360 kJ m?2). Hot water weed control should thus be carried out when the plants are drought stressed and avoided when the plants are wet. The air temperature seems to be of little importance in the range 7–18°C. 相似文献
15.
内蒙古旱作农区农业干旱灾害度初步研究 总被引:2,自引:0,他引:2
甄江红 《干旱区资源与环境》1997,11(2):93-98
本文通过对旱作农区旱灾的孕实环境、旱灾特征及灾情分析,提出了一种综合评价旱灾对农业生产危害程度的定量化方法,并在此基础上对旱作农区各旗(县)进行灾情分区,从而为抗旱减灾提供理论依据。 相似文献
16.
青海省干旱预警服务系统设计与建立 总被引:7,自引:1,他引:7
在阐述青海省干旱概念、类型、成因与评估指标的基础上,确定了旱情监测区域。以地面常规监测、气候监测和空间遥感监测相结合为基础,设计和建立了"监测—评估—预测、预警"信息业务系统,可为研究干旱发生规律,及时监测和预测干旱的发生,评估干旱程度以及制定防灾、减灾、救灾提供科学依据。 相似文献
17.
干旱指数及其在青海东部旱区特征分析上的应用 总被引:5,自引:0,他引:5
缪祥辉 《干旱地区农业研究》2004,22(2):136-141,153
在土壤水分平衡关系分析的基础上,提出了分析和评估旱害的5项指标:贫水指数、凋萎指数、降水指数、综合指数和干旱指数,并依据干旱指数对乐都浅山地区1961~1999年的粮食生产进行了年型分类。结果为:39a间共发生特大旱1a,大旱年3a,中旱年19a,轻旱年11a,平水年5a;发生机率分别为2.6%、7.69%、48.72%、26.21%、12.82%。同时认为青海东部地区旱区作物需水和耗水参数矛盾突出,干旱几乎年年发生,具有明显的难以预测性、多变性和不可控性。 相似文献
18.
Influence of the root endophyte Piriformospora indica on the plant water relations,gas exchange and growth of Chenopodium quinoa at limited water availability
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S. Hussin W. Khalifa N. Geissler H.‐W. Koyro 《Journal of Agronomy and Crop Science》2017,203(5):373-384
This study aimed to evaluate the ability of Piriformospora indica to colonize the root of Chenopodium quinoa and to verify whether this endosymbiont can improve the growth, performance and drought resistance of this species. The study delivered, for the first time, evidence for successful colonization of P. indica in quinoa. Hence, pot experiment was conducted in the greenhouse, where inoculated and non‐inoculated plants were subjected to ample (40%–50% WHC) and deficit (15%–20%WHC) irrigation treatments. Drought adversely influenced the plant growth, leading to decline the total plant biomass by 74%. This was linked to an impaired photosynthetic activity (caused by lower gs and Ci/Ca ratio; stomatal limitation of photosynthesis) and a higher risk of ROS production (enhanced ETR/Agross ratio). P. indica colonization improved quinoa plant growth, with total biomass increased by 8% (controls) and 76% (drought‐stressed plants), confirming the growth‐promoting activity of P. indica. Fungal colonization seems to diminish drought‐induced growth hindrance, likely, through an improved water balance, reflected by the higher leaf ψw and gs. Additionally, stomatal limitation of photosynthesis was alleviated (indicated by enhanced Ci/Ca ratio and Anet), so that the threat of oxidative stress was minimized (decreased ETR/Agross). These results infer that symbiosis with P. indica could negate some of the detrimental effects of drought on quinoa growth, a highly desired feature, in particular at low water availability. 相似文献
19.
Sorghum [Sorghum bicolor (L.) Moench] is a drought‐tolerant crop, and its productivity in rain fed environments has increased since the 1950s. This increase is due to changes in agronomic practices and hybrid improvement. The objective of this study was to determine what aspects of grain sorghum morphology, physiology and water use have changed with hybrid improvement and might have contributed to this yield increase. A 2‐year greenhouse experiment was conducted with one hybrid from each of the past five decades. The hybrids were studied in well‐watered and pre‐ and post‐flowering water deficit conditions. Total water use, transpiration, stomatal conductance and photosynthesis were measured during the growing period. Biomass and biomass components were measured at harvest. There was no consistent change in the leaf physiological parameters resulting from hybrid advancement. In contrast, total water use increased in rate of 8.5 cm3 kg soil?1 year?1 from old to new hybrids in the well‐watered treatments. Root biomass also increased in rate of 0.2 g plant?1 year?1. Leaf biomass and panicle length also was greater for the newest compared with the older hybrids. Hybrid advancement was related to increase in panicle length but decrease in peduncle length. Results indicated that hybrid development programmes created hybrids with improved drought avoidance, due to better root density of newly released hybrids, or hybrids with better resource use which ultimately increased yield under rain fed conditions. 相似文献
20.