绿洲灌溉区与旱作区多龄苜蓿地土壤有机碳、氮及物理特性分析

以甘肃灌区和旱作区苜蓿(Medicago sativa)地土壤为研究对象,对不同地域的苜蓿地土壤全氮(TSN)、有机碳(SOC)、容重、含水量进行测定,结果表明:灌区SOC含量均高于旱作区,在90~100cm土层其含量与旱作区差值最大,达3.41g/kg。在0~100cm灌区SOC含量为6.81~12.49g/kg,均值为9.25g/kg,比旱作区高22%。旱作区TSN含量随土壤深度的增加而减小,含量在(1.03±0.01)~(0.44±0.04)g/kg。在0~30cm灌区TSN含量相对较稳定,差异不显著(P0.05),在30~60cm剖面全氮含量急剧下降,70~100cm含量变化较为稳定,TSN含量维持在(0.66±0.01)g/kg。旱作苜蓿地土壤含水量在0~60cm变化不显著(P0.05),0~100cm土壤含水量均值为(14.437±1.124)%,灌区苜蓿地土壤含水量均值为(16.025±2.029)%。随着土壤深度的增加,旱作区和灌区苜蓿地土壤容重均呈现依次增大的分布规律,旱作区最大值为(1.421±0.034)g/cm,比最小值高出17.5%,灌区最大值(1.332±0.017)g/cm,比最小值高出11.3%.     

草坪灌溉与排水课程设计的关键环节分析

为了提高草业科学本科生创造性和独立性,要求学生完成喷灌系统课程设计。该课程设计特点是公式多、难记忆、抽象和难掌握。在课程设计过程中,学生经常找不到切入点,不知道各环节计算公式和各环节之间的联系。通过对多年教学过程的总结和概括,分析设计灌水定额和灌水周期、喷头布置和选型、轮灌组划分等关键环节,进一步阐明各关键环节之间的联系,以期指导学生更好掌握草坪灌溉与排水课程,达到满足草坪草用水、节约用水、形成水动景观效果、解决我国水资源紧张等目的。     

不同灌溉条件对刺槐生长量及各项生理指标的影响

在小管出流与大水漫灌等不同灌溉方式下,研究刺槐的相对含水量(RWC),水分饱和亏缺(RWD)、光响应曲线、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)、单叶水分利用效率(WUE)等指标的变化。结果表明,小管出流灌溉条件下,刺槐叶片净光合速率Pn值、蒸腾速率、气孔导度、生长量均大于漫灌下刺槐;但是,单叶水分利用率与叶片胞间CO2浓度在这2两种灌溉条件下差异较小。     

滴灌条件下4种树木生长发育规律的研究

通过对南疆干旱地区荒山绿化所采用的胡杨、沙枣、柽柳和白榆等4种主要造林树种在滴灌条件下的生长发育规律进行研究,结果表明:4种树木在滴灌条件下根系分布存在着明显差异;生长高峰期到达的时间不同,白榆生长高峰期最长,其次为沙枣、胡杨、柽柳;4种树木耐盐程度不同,柽柳耐盐性最强,在总盐含量2.26%的情况下,尚能生长。     

Evaluation of coastal sandy soils and their saline ground waters for afforestation: A case study from India

A study was conducted in coastal Andhra Pradesh to evaluate current practices and suitability of coastal sandy soils for raising tree plantations. Poor soil moisture retention characteristics of these soils make irrigation an essential, but costly silvicultural practice for obtaining desirable establishment and growth. Saline ground water is the only available source of irrigation. Its use seems safe and successful in such soils. The farmers have adopted a specialized manual splashing technique (Doruvu) of seepage pits for irrigating tree plantations in their establishment phase. This technique was observed to be well suited to the sandy soils. Casuarina equisetifolia and Eucalyptus tereticornis were the two most popular species being afforested. E. camaldulensis is also in an introduction phase. Comparison of growth performance and biomass accumulation by C. equisetifolia and E. tereticornis plantations at different growth stages showed the former to be significantly better than the latter. Build up of the soil organic carbon was also found to be markedly more in comparable C. equisetifolia plantations than those of E. tereticornis. Similarly, the blanketing influence of C. equisetifolia plantations was observed to modify soil temperature extremes considerably more than in the case of E. tereticornis. The findings, indicated a vast scope for utilization of coastal sandy soils for afforestation with the successful use of saline ground waters.     

退化人工梭梭林的恢复技术研究

对退化人工梭梭林进行恢复试验研究发现:滴灌可使梭梭林地土壤含水率显著提高;梭梭光合作用增强;群落物种数增多,盖度增大;防风固沙作用增强.布设机械沙障可使退化梭梭林地表粗糙度增大,林内近地面层风速、输沙量显著下降.春灌3 a后,不仅退化梭梭个体恢复正常生长,同时梭梭林群落物种组成数明显增加,盖度显著增大,生态功能也逐渐恢复.雨水集流和雨水下渗改造两种模式应用1～2 a后,退化梭梭林地土壤含水率均有明显提高.滴灌、布设机械沙障、春灌和改造结皮4种技术措施对退化梭梭林生长及其环境均有明显的恢复作用,其中滴灌、机械沙障恢复技术是当前和今后推广的主要措施;春灌和改造结皮可作为前两种技术的补充措施.     

干旱半干旱地区人工牧草节水灌溉技术研究进展

对干旱半干旱地区人工牧草节水灌溉技术的研究状况进行了回顾和总结，并提出了今后西部干旱半干旱地区人工牧草节水灌溉技术研究的重点内容与方向。     

Effect of water stress conditioning on morphology,physiology and field performance of Pinus halepensis Mill. seedlings

Five-month-old Pinus halepensis Mill. seedlings were subjected to 4 irrigation treatments for 8 weeks. After the treatments, morphological and physiologicalattributes assessed included height, diameter, dry weight, water relations parameters, and determination of N, P, K, soluble carbohydrates, and starch concentrations. The remaining seedlings were field planted. Survival and height growth were recorded forfour growing seasons after planting. The mostsignificant effect of irrigation was onmorphology. Increased irrigation lead toseedlings with significantly higher height,root collar diameter and shoot and rootbiomass. Starch and soluble carbohydrateconcentrations were also affected byirrigation. However, parameters derived frompressure-volume curves were not significantlydifferent among treatments, nor were N, P, andK concentrations. There were no differencesamong treatments for survival in the field,which was highly related to summer rainfall. Incomparison, absolute and relative heightgrowth showed some significant but minordifferences among treatments.     

不同水分条件下皮叶两用杜仲林的生长效应

对12年生杜仲进行人工供水处理,研究土壤水分对皮叶两用杜仲林萌条生长规律的影响.结果表明:不同水平的供水对新枝生长均有促进作用,6~9月份,Ⅰ、Ⅱ、Ⅲ、Ⅳ级供水处理的新枝枝长生长量分别较对照增加30.2%、37.1%、77.9%、56.2%,新枝直径生长量分别较对照增加22.4%、53.7%、117.9%、83.6%;Ⅲ级供水最有利于萌条的生长,二次分枝数最多(43个/株),平均枝条长度最长(27.3 cm),单株叶片数和叶干质量分别为162个.株-1和16.5 g.株-1;杜仲供水多时,水分并不能被根部全部吸收,水分利用效率降低;5~9月份,秦岭南坡杜仲适宜的灌水量为1 050 m3.hm-2.     

Effects of temperature,water regime and irrigation system on the release of ascospores of Mycosphaerella nawae,causal agent of circular leaf spot of persimmon

Experiments were conducted under controlled conditions to quantify the effects of temperature, water regime and irrigation system on the release of Mycosphaerella nawae ascospores from leaf litter in Spanish persimmon orchards. The effect of temperature on ascospore release was best described by a Gompertz model. The end of the lag phase of ascospore release occurred at 9·75°C, and the end of the exponential phase at 15·75°C. Few ascospores were discharged from dry leaves wetted with 0·1 or 0·5 mm water, but significant amounts were recovered with 1–50 mm water. About half of the total ascospores were released after three wetting and drying cycles, but 32 cycles were necessary for a complete discharge. No significant difference in ascospore release was detected when the leaf litter was wetted by flood and drip irrigation. However, considering the proportion of soil area wetted in both systems, inoculum release was significantly reduced by drip irrigation. The potential of drip irrigation as a cultural control measure should be investigated.