Cytokinin and gibberellin delay regreening of spathe tissue of Zantedeschia ‘Best Gold’

Spathe regreening is a primary determinant limiting the postharvest quality for most hybrids of Zantedeschia, e.g. ‘Best Gold’, wherein the spathe commences regreening approximately two days after it is fully open. To identify an effective method to postpone the regreening, several synthetic plant hormones were evaluated for their influence on changes in color during regreening of discs excised from the spathe of ‘Best Gold’. The tested synthetic plant hormones included 6-benzylaminopurine (BAP), zeatin, N₁-(2-chloro-4-pyridyl)-N₃-phenylurea (CPPU) and GA₃ at concentrations up to 0.1 mM. A concentration of BAP at 0.5 mM resulted in phytotoxicity symptoms on discs. Subsequently, the effect of a combination of BAP and GA₃ on the regreening was examined. Application of the cytokinins (in particular BAP at 0.1 mM) or GA₃ alone resulted in a one to five day delay in regreening on the spathe tissue. The most effective treatment in delaying regreening was from the simultaneous application of GA₃ and BAP in a ratio of 1:1 (v:v) at 0.1 mM, wherein regreening was delayed for more than ten days. This treatment was then tested on the entire inflorescence, resulting in a delay in regreening for between seven and eight days.     

复测角规样本估计蓄积生长量的新方法

角规是一种效率高的测树方法。但用常规角规方法测林分蓄积生长量,在前后两期计数木相同的情况下,断面积生长量为0;如前后期计数木不同,则每相差一株计数木,对单位面积断面积和蓄积的生长量影响颇大。这种跳跃式变化往往不符合林分生长实际,从而影响这一方法的推广采用。为此,曾提出过许多其他用角规测林分蓄积生长量的方法。这些方法可概括分为两类。一类是直接方法,其前后两期都计数的保留木对林分蓄积生长量贡献很小,其断面积生长量为0,蓄积生长仅是形高生长。保留木断面积生长量     

绞盘机用多滚子凸轮超越离合器设计理论研究

本文结合我国引进ＣＡＴ５１８绞盘机设计理论的消化，讨论了多滚子凸轮超越离合器的楔紧条件，在其基础上给出了绞盘机用多滚子凸轮超越离合器最大扭矩传递能力的具体计算方法和凸轮轮廓结构参数的确定方法。     

Effect of Water Status on Leaf Angle and Leaf Movement in Wheat

Water stress was imposed by watering withholding or application of PEG during the period following ligule emergence of Hag leaves or fifth leaves. Treatment reduced markedly the downward rotation of these youngest fully expanded leaves, and the angle finally reached. Leaf angle changes appear to be sensitive indicators of water shortage in wheat.     

水稻根系分布与叶角关系的研究初报

1983—1984年,通过群体水培、土培试验,在控制水稻根系不同分布空间形状情况下,研究了叶角与根系分布的关系,其结果主要表现如下:1.根系分布较深且多纵向时,叶角较小,叶片趋向于直立;根系分布较浅且少纵向时,叶角较大,叶片趋向于披垂。2.叶角的大小同时受叶片大小的影响,根系分布较浅且少纵向时,较大的叶片更易披垂,叶角更大,     

Cotyledon angle as a predictor of growth rate of cucumber plant

Summary Experiments conducted in the greenhouse and in the field indicated that plants produced from seedlings of Cucumis sativus L. which displayed their cotyledons in an upward position grew faster than plants which displayed their cotyledons in a downward position. Cotyledon angle was not a function of seed size nor seedling weight at 10 days after planting. An increase in plant height, node number, and fresh weight at later growth stages was associated with an upward cotyledon angle and persisted until time of harvest. Anthesis tended to occur later in plants having a downward cotyledon angle. The number of pistillate flowers was greater in plants with an upward cotyledon angle compared to those with a downward cotyledon angle. Differences in yield (fruit number) were not associated with cotyledon angle.Paper No. 5432 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, NC. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Experiment Station of products named, nor criticism of similar ones not mentioned.     

Improvement of durum wheat-plant type,yield potential,and adaptation

Summary Improvement of durum wheat at the International Maize and Wheat Improvement Center (CIMMYT) was achieved by exploiting the variability of the tetraploid species in large numbers of combinations, and multi-location testing of germplasm on a world wide base. High yielding, widely adapted durums with short straw, good fertility, and adequate earliness were selected for distribution to major durum growing countries. Present attempts to improve durum wheat are directed at adjusting agronomic traits such as leaf angle and straw strength, and increasing spike fertility and spike size, thereby reaching higher grain numbers per unit area and higher yield potential. Diversification of the developmental pattern and incorporation of drought tolerance aim at further widening adaptation.     

Inheritance of leaf angle in Triticum aestivum L.

Summary A 6×6 diallel was prepared to study the inheritance of leaf angle in T. aestivum L. Genetic analysis in terms of diallel cross parameters and graphic analysis indicated the control of additive gene effects in the expression of this character. The results of F₁ analysis were supported by the analysis of F₂ data.     

外掺植物纤维对冻融作用下植被混凝土抗剪强度的影响

[目的]研究外掺2种植物纤维对冻融作用下植被混凝土抗剪强度的影响,为植被混凝土生态防护技术在高寒地区的应用提供科学依据。[方法]参考相关标准(GB/T50082-2009)中的慢冻法,采用2因素3水平全面交叉试验开展研究。[结果]未掺植物纤维的植被混凝土,冻融后黏聚力显著减小,内摩擦角变化不明显。掺入植物纤维可使经受5次冻融循环作用后植被混凝土的内摩擦角平均增加5°左右,并且随植物纤维掺量的增加,内摩擦角变化无明显规律,黏聚力则呈先增加后减小的趋势。表明纤维加筋对黏聚力的贡献存在临界掺量。棕纤维掺量对黏聚力的影响比黄麻纤维掺量更为敏感。[结论]外掺植物纤维可有效改善植被混凝土抵抗冻融破坏的能力,棕纤维和黄麻纤维的建议掺入比为0.6%和0.6%,具备推广应用前景。     

基于理想传动比的主动前轮转向控制

针对目前汽车主动前轮转向系统缺少对理想传动比规律研究的问题,建立线性二自由度车辆模型、主动前轮转向系统模型,以及轮胎模型;设计固定横摆角速度增益下的主动前轮转向系统理想传动比规律,提出基于该规律的主动前轮转向附加转角闭环控制策略,并对提出的控制策略进行仿真分析和试验验证。结果表明:基于理想传动比的前轮主动转向附加转角控制策略可有效保证车辆在低速时横摆角速度响应幅值变大,车辆具有较好的操纵性;高速时横摆角速度和质心侧偏角响应的幅值均变小,车辆具有较好的稳定性,有利于车辆获得较为理想的转向品质。研究结果可为主动前轮转向系统的设计与开发提供理论基础。