不同种植方式对红壤旱地土壤水分及抗旱能力的影响

通过3年田间小区试验,研究不同种植方式对红壤旱地土壤水分及抗旱能力的影响.结果表明：1）与种植花生相比,种植苎麻可显著提高土壤有机质质量分数（28.44％）、田间持水量（10.06％）和总孔隙度（5.65％）,土壤密度则显著降低7.20％;2）监测期内,花生地各层土壤以及整个0～ 100 cm土体水分变异系数普遍高于苎麻地,苎麻地0 ～ 100 cm土体水分的时间稳定性和空间协调性优于花生地;3）苎麻地0～ 40 cm土壤较花生地延长抗旱时间7d以上,但随着土层的加深,差异越来越小;4）红壤坡耕地种植苎麻有利于提高红壤旱地土壤抗旱能力,特别是中、上层土壤.从扩充土壤水库的角度考虑,红壤旱地种植苎麻优于种植花生,该研究结果可为挖掘红壤区深层土壤水分提供参考.     

水肥一体化对红麻生长、纤维产量与品质的影响

【目的】研究水肥一体化（滴灌施肥）对红麻生长、纤维产量和品质的影响,探讨红麻水肥利用特点,为红麻高产高效栽培提供参考。【方法】大田试验设6个滴灌施肥处理和1个对照（CK）,CK采用100%灌水量（16.183 m3）和100%施肥量（264.00 kgN/ha,88.04 kgP2O5/ha,176.09 kgK2O/ha）,撒施、沟灌;处理T1~T3均采用100%灌水量、施肥量分别为100%、75%和50%,处理T4~T6采用80%灌水量（12.947 m3）、施肥量分别为100%、75%和50%。收获时考察不同处理红麻农艺性状和纤维指标。【结果】与常规施肥、灌溉相比,6个滴灌施肥处理可显著促进红麻的生长和改善纤维品质,红麻株高、茎粗、皮厚、地上部干质量、纤维产量和纤维线密度分别显著增加13.2%~25.5%、0.7%~1.4%、10.6%~20.3%、12.5%~30.9%、15.1%~36.8%和7.2%~30.7%,其中以T1处理的综合效果最好,其次为T5、T2。T1处理的株高、地上部分干质量、纤维产量等最高,但大部分与T5处理差异不显著,而处理T5的纤维强力显著高于处理T1。【结论】滴灌施肥时,T5处理（80%灌水量：12.947 m3,75%施肥量：198.0 kgN/ha,66.03 kgP2O5/ha,132.07 kgK2O/ha）可获得较好的节水节肥效果,建议在红麻生产上推荐应用。     

减弱光照强度对水稻叶片气孔性状的影响

采用改良刮制法研究了典型粳稻，典型籼稻，偏籼型，偏粳型和陆稻等10个水稻品种的气孔性状，研究结果发现，剑叶的气孔密度在水稻类型间和品种间具有明显差异。是一个品种特性，光照强度减弱使各品种上三叶的气孔密度明显减少。其原因是由于叶面积增大，气孔行数减少和每一行中相邻气孔间距离增大共同作用的结果。品种不同，其气孔密度对光强变化的反应亦不同，光照强度减弱对剑叶气孔大小有显影响。     

不同种植密度对甘蔗品种桂糖32号产量及构成因子的影响

[目的]探寻桂糖32号适宜的种植密度,为在河池蔗区推广桂糖32号提供栽培技术指导。[方法]试验研究5种不同的种植密度(1:7.5万芽/hm2、2:9.0万芽/hm2、3:10.5万芽/hm2、4:12.0万芽/hm2和5:13.5万芽/hm2)对桂糖32号萌芽率、分蘖率、产量构成因子、蔗茎产量及含糖量的影响。[结果]研究结果表明:不同的种植密度对桂糖32号的萌芽率和茎径影响不大;桂糖32号分蘖率随其种植密度的增加而有所降低;有效茎数、产量及含糖量随其种植密度的增加而增加。与7.5万芽/hm2相比,9.0万、10.5万芽/hm2种植密度能增产3.99、4.47 t/hm2和增糖0.23、0.74 t/hm2,而12.0万、13.5万芽/hm2种植密度能显著增产7.63、12.01 t/hm2和显著增糖1.57、1.75 t/hm2。[结论]河池蔗区桂糖32号适宜的种植密度在12.0万~13.5万芽/hm2,最佳的种植密度在13.5万芽/hm2左右,在此密度下可获得较高的蔗茎产量和含糖量。     

Effects of time and concentration on mortality of phosphine-resistant Sitophilus oryzae (L) fumigated with phosphine

The effects of exposure period and phosphine concentration on mortality of susceptible and resistant Sitophilus oryzae (L) were investigated. Although S oryzae is one of the world's most serious pests of stored grain there are few data on the practical significance of phosphine resistance in this species. The strains investigated were an Australian susceptible strain, a homozygous resistant strain exhibiting a level of resistance common in Australia and an unselected field strain from China with a much stronger resistance. Fumigations were carried out at 25 degrees C on adults and mixed-age cultures. For adults of all three strains and mixed-age cultures of the susceptible and resistant Australian strains, the relationship between concentration and time could be described by equations of the form Cnt = k. In all cases n < 1, indicating that time was a more important variable than concentration. In all fumigations of adults the resistant strains were harder to kill than the susceptible strain. However, in fumigations of mixed-age cultures, which contained the tolerant pupal stage, the difference between susceptible and resistant strains was more pronounced at lower concentrations than higher concentrations. For example, at 0.02 mg litre-1 the estimated LT99.9 for mixed-age cultures of the Australian resistant strain (27 days) is 3.4 times that of the susceptible strain (8 days), but at 1 mg litre-1 there is no difference between the two strains (4 days). Limited data on the Chinese resistant strain supported this finding. Twenty-three days exposure at 0.02 mg litre-1 had no effect on mixed-age cultures of this strain, but there were no survivors after 5 days exposure to 1 mg litre-1.     

Tree and stand structure of the non-native Pinus contorta in relation to native Pinus sylvestris and Picea abies in young managed forests in boreal Sweden

Managed forest stands are typically younger and structurally less diverse than natural forests. Introduction of non-native tree species might increase the structural changes to managed forest stands, but detailed analyses of tree- and stand-structures of native and non-native managed forests are often lacking. Improved knowledge of non-native forest structure could help clarify their multiple values (e.g. habitat for native biodiversity, bioenergy opportunities). We studied the structural differences between the introduced, non-native Pinus contorta and the native Pinus sylvestris and Picea abies over young forest stand ages (13–34 years old) in managed forests in northern Sweden. We found that P. contorta stands had greater mean basal areas, tree heights, diameters at breast height, and surface area of living branches than the two native species in young stands. The surface area of dead attached branches was also greater in P. contorta than P. abies. Although this indicates greater habitat availability for branch-living organisms, it also contributes to the overall more shaded conditions in stands of P. contorta. Only one older 87 years old P. contorta stand was available, and future studies will tell how structural differences between P. contorta and native tree species develop over the full forestry cycle.     

牛姆林区青钱柳群落的主要种群种间关联特征

通过一系列种间关联测定技术 (方差比率 ( VR)法检验多物种间总体相关性、χ2 检验各种对间的联结性、关联指数测度各种对间的关联程度 )对青钱柳群落的 1 2个主要乔木种群的 1 2个主要种群的种间关联分别进行检验与测度 ,结果表明 :青钱柳群落的 1 2个主要乔木种群间在总体上表现出无关联 ,各种对间的联结性不显著 ,关联程度也较低 ,各自趋于独立出现 ,这种“松散”状况可能与该群落处于过熟发展阶段有关     

养殖密度对革胡子鲶生长性能及补体C3·C4的影响

[目的]研究养殖密度对革胡子鲶生长性能及血清补体C3、C4的影响。[方法]以体重（30.71±0.89）g革胡子鲶为试验对象,测定4种养殖密度（35、65、95、125 kg/m3）下革胡子鲶生长性能及血清补体C3、C4的变化。[结果]养殖60 d后,随着养殖密度升高,革胡子鲶终末重、日增重均呈下降趋势,其中35 kg/m3与65 kg/m3密度组间差异不显著（P〉0.05）。各密度处理组间饵料系数均无显著差异（P〉0.05）。低密度处理组（35 kg/m3与65 kg/m3）与高密度处理组（95 kg/m3与125 kg/m3）间死亡率差异显著（P〈0.05）。养殖密度对补体C3、C4的影响不显著（P〉0.05）。[结论]65 kg/m3可推荐为革胡子鲶的最佳养殖生产密度。     

人工接种堆肥和自然堆肥微生物区系变化的比较

[目的]为了明确堆肥过程中微生物菌群的组成与变化,为堆肥工艺的优化和人工接种腐熟菌群的应用提供理论依据。[方法]采用传统的平板培养技术研究了人工接种堆肥、自然堆肥微生物群落演变过程。[结果]传统培养方法显示两种堆肥过程中微生物群落演变均呈"升高-降低-升高-降低"变化,堆肥整个过程中细菌数量占优势;人工接种NMF菌群增加了堆肥中微生物总体数量,丰富了微生物种群多样性,促进了堆肥菌群演替,堆肥腐熟时间缩短;接种NMF菌群能够提高堆肥纤维素分解菌、放线菌、氨化细菌、硝化细菌数量,减少堆肥反硝化作用,有利于纤维素、木质素等难降解物质的分解、转化为腐殖质,同时能够减少堆肥过程中氮素损失。[结论]研究堆肥过程中微生物区系的演变对于了解堆肥进程、优化堆肥工艺具有重要的意义。     

纳米粒子系统屏蔽效应和电荷电势分布研究

建立了纳米粒子系统屏蔽效应的物理模型,应用电动力学理论求出了系统的电荷和电势分布以及屏蔽参量.以Cu和Al粒子为例,探讨了粒子线度和材料对纳米粒子系统的电荷、电势分布和屏蔽参量的影响.结果表明:两种不同金属纳米粒子构成的系统,其电荷密度和电势分布与单个带电粒子的电荷和电势分布不同,它们不仅与粒子的线度有关,而且还与粒子数密度、电子费米能、纳米粒子的分布范围等有关;两种粒子的电荷符号和密度分布不同:一种粒子的电荷密度为正且随离中心的距离增大而增大,而另一种粒子的情况相反;电荷密度随距离的变化快慢取决于粒子的线度,电荷密度的变化主要发生在两种粒子分布区域的分界面附近;系统的电势分布在两种粒子分布区域分界面处取极小值,其屏蔽参量要比块状晶体的值要小,与粒子线度、费米能、粒子数密度和分布范围等都有关.理论结果与文献给出的实验资料一致.