The impact of timing and duration of grass control on growth of a young Eucalyptus globulus Labill. plantation

Interference by an introduced grass, Holcus lanatus L. (Yorkshire fog grass) in a young E. globulus (Tasmanian blue gum) plantation was investigated. The objectives were to determine (1) the critical period of competition, and (2) how the timing and duration of competition was related to the interaction between tree growth and resource availability. This was investigated during the first two years of establishment. Weed interference was severe with height and diameter growth of weedy trees being 52% and 40% of weed-free trees, respectively, at age two years. Most growth losses occurred during the first year. The critical period of weed interference was from planting to age 18 m and effective weed control was required for this period to maximise tree growth potential. The application of nitrogen to weedy trees promoted a significant growth response suggesting that competition for nitrogen was occurring. There was no significant response to level of irrigation. The use of critical period analysis is discussed.     

不同嫁接方法对核桃苗嫁接成活率和出圃率的影响

为探讨适宜保康县核桃苗木繁育方法,采用春季劈接和夏季留放水口露芽接、不留放水口露芽接、留放水口包芽接、不留放水口包芽接4种芽接方法进行嫁接,比较5种方法的成活率和出圃率,结果表明:在保康及附近区域,夏季采用芽接方法能有效地提高嫁接成活率和出圃率。     

论封山育林的规划设计

封山育林是培育森林资源的一条十分重要的途径，文中就封能林的范围，。封山育林规划设计中的空间配置，封育年限，育林措施等几个问题进行了探讨，提出了自己的观点。     

棉花早期热激处理与高温期蕾铃脱落关系的初步研究

研究了棉花早期热激处理与高温期蕾铃脱落的关系，结果表明：早期热激处理有助于高温期棉株体内产生更丰富的热激蛋白，从而提高棉株的耐热程度，降低脱落率达１．７～３．０个百分点。但不同的品种，早期热激处理的最适生长阶段不同品种有差异     

关于杂稻制种幼穗分化期多效唑施用效果的数学模型研究

试验采用饱和D—最优计划设计，研究了多效唑使用剂量、浓度、时期与产量、包颈率、结实率、花调效果等的关系，分别得出了它们的回归数学模型。研究结果揭示了多效唑是以影响始穗期、包颈率和结实率而最终影响到产量的。综合分析认为，要延迟母本始穗期，减少包颈率、提高结实率，夺取制种高产多效唑施用的最佳剂量为153克．浓度322ppm，时期为幼穗分化第四期。     

结实期土壤水分对水稻产量与品质的影响

以汕优63(杂交籼稻)和武育粳3号(粳稻)为材料,自抽穗至成熟期,设盆钵内土壤水势5个处理为0(对照)、-15、-30、-45、-60kPa,研究了土壤水分对产量和稻米主要品质性状的影响。结果表明,当汕优63土壤水势为-15kPa和-30kPa、武育粳3号土壤水势为-15kPa时,结实率、千粒重和产量较对照显著增加。结实期土壤水分对稻米的出糙率、精米率、粒长/粒宽、直链淀粉含量和粗蛋白含量无显著影响。汕优63土壤水势为-15kPa和-30kPa处理及武育粳3号土壤水势为-15kPa处理的整精米率与对照无显著差异,垩白米率、垩白度和消减值较对照显著降低,淀粉谱的最高粘度和崩解值则显著增加。汕优63土壤水势为-45kPa和-60kPa处理以及武育粳3号土壤水势为-30kPa、-45kPa和-60kPa的处理的结实率、千粒重、产量、整精米率、胶稠度、碱消值、最高粘度和崩解值较对照显著降低,垩白米率、垩白度和消减值较对照显著增加。建议将土壤水势为-15kPa与-30kPa和-15kPa分别作为汕优63和武育粳3号结实期优质高产节水灌溉的低限土壤水势指标。     

THE STRUCTURE SPACE ANALYSIS OF THE MAIN TALL BUILDING OF CHONGQING JIANGBEI COMMERCIAL CENTER

The determination of the structural plan of the main tall building of ChongqingJiangbei Commercial Center is introduced. In anti-seismic analysis,bend-torsion coupling vibrationis compared with plane vibration.Earthquake actions from any different directions for the structureare analysed also.The result of using direct dynamic analysis method is compared with that of usingSRSS method.     

Some Key Technologies and System Development of Distribution Management on Time Limited Consumable

According to the characteristic of Time Limited Consumable and feature of line in Time Limited Consumable, some key technologies of if one studied, including early warning rule of product guarantee period, real time control strategy of available sale quantity when considering products being overdue, distribution pattern integration in Time Limited Consumable, and business process reengineering. On the basis of the above study, distribution management system oriented time limited consumable is constructed and implemented for validation with good effect.     

早熟高产玉米单交种生育特性与产量构成的关系

早熟玉米单交种子粒产量低的主要原因是营养生长期短，形成的叶片少且面积小，光合产物供应不足，从而导致穗部性状的劣化和子粒产量的不稳定性。以早熟为前提子粒高产的育种途径，除配合力选育外，还可以通过提高叶片生长率来实现。通过试验研究提出，在高配合力前提下把具有潜在高灌浆速率的早熟自交系同一定的中晚熟自交系组配单交，不仅可使营养生长期显著延长，同化物供应改善，而且也可使灌浆期显著缩短，从而达到早熟高产的目的。     

品种类型与营养生长积温对小麦穗部性状的影响

大穗型，中间型和多穗型品种具有各自不同的穗、粒、重间的协调平衡关系。以高产为目标，最适穗容量平衡点呈多穗型＞中间型＞大穗型。营养生长基础对群体穗粒重的效应为多穗型＞大穗型＞中间型。穗粒数的增加是提高穗粒得的有效途径，增加小穗数／穗对高结实率品种 有效，减少不孕小穗数／穗对环境敏感型品种效应显著。