我国蔬菜生产现状与良好农业规范的对比

以蔬菜生产的可追溯性、种苗、肥料、灌溉、植保、采收等为基础控制点,将我国蔬菜生产现状与良好农业规范（GAP）进行了对比。通过对比分析,找到了两者之间的差距,并指出了我国蔬菜生产今后的发展方向。     

福建结球甘蓝氮磷钾施肥指标研究

根据59个氮磷钾肥效试验结果,研究了福建结球甘蓝氮磷钾施肥指标。结果表明,平衡施肥产量与空白区产量呈现线性正相关关系,土壤养分对结球甘蓝产量的平均贡献率为51.0%,施用氮磷钾平均增产40.4%、11.6%和15.0%;土壤速效氮磷钾高产临界指标分别为碱解氮207 mg/kg、Olsen-P 71 mg/kg和速效钾157 mg/kg;平均经济施肥量为N 238 kg/hm2、P2O5 70 kg/hm2和K2O 192 kg/hm2,三要素比例为1∶0.29∶0.81;土壤有效氮磷钾测定值与推荐施肥量之间满足指数回归方程,根据土壤养分测定值可推算结球甘蓝推荐施肥量,起到因土施肥的作用。     

Diagnosis tool for plant and crop N status in vegetative stage: Theory and practices for crop N management

The environmental constraints to agriculture imply that nitrogen (N) fertilizer management should be adjusted to crop N requirements determined by target yields. Nowadays for environmental and economical reasons target yield of farmers can be lower than the potential crop yields as permitted by soil and climatic conditions. So it is important to provide farmers crop N status diagnostic tools in order to decide the rate and the timing of N fertilizer applications. Theory on crop N uptake and allocation allows the determination of a diagnostic tool, the Nitrogen Nutrition Index, based on the determination of the critical N dilution curve for each crop species considered. During the vegetative growth period of all the crop species studied, including C3 and C4 species and monocots and dicots, plant N concentration decreases monotonically as crop grows because of (i) the ontogenetic decline in leaf area per unit of plant mass, and (ii) the remobilisation of N from shaded leaves at the bottom of the canopy to well illuminated leaves at the top. NNI appears then as an indicator well connected with the physiological regulation of N uptake at canopy level. So this indicator can be used as the basis for determination of crop N nutrition status, and then for decision making on the necessity of an N application for achieving target yield. Nevertheless despite its high physiological relevance, NNI cannot be used directly in farm conditions because its determination is very time consuming. So it is necessary to develop indirect methods for NNI estimation through more operational procedures. Several methods have been proposed in literature, such as nitrate concentration in sap or chlorophyll meter. But the calibration or validation of these methods with NNI have not been always made and, when they have been, they did not give univocal relationships, showing a strong dependence of the relationship with cultivar and environment, that limits considerably the relevance of such diagnostic tools in a large range of situations. Easier to use is the indirect estimation of crop NNI by remote sensing measurements. This method allows the estimation of both actual crop mass, through LAI estimation and crop N content, through crop chlorophyll content. The possibility to have repeated estimations of crop NNI during the period of vegetative growth would allow a dynamic diagnostic tool of crop N status. The coupling of indirect measurements of crop N status with dynamic models of crop growth and development should allow a very promising method for crop N diagnostics for decision tools in N fertilization.     

浅谈农林高校哲学教育创新

当前农林高校的哲学教育存在很多困难。解决问题的出路是进行哲学教育创新。哲学教育创新包括哲学教育功能创新、哲学教育理念创新、哲学教育师生关系创新、哲学教育教学方式创新、哲学教育实践环节创新和哲学教育考核策略创新六个方面。     

The influence of fiber length distribution on the accelerated points in drafting: A new perspective on drafting process

The distribution of the accelerated points of fibers in roller drafting is the key to the evenness of the drafted slivers. The fiber length distribution is believed to affect the accelerated points. This approach is trying to give a quantitative expression of the influence. A parabolic density function is introduced for the expression of density functions and a generalized method is presented. The experiment shows that the parabolic-type density function is a better explanation for the distribution of the accelerated points in the drafting zone in terms of the consequent yarn unevenness. The statistical test verifies the distribution type. The analysis helps to understand the mechanism of the roller drafting and can be used in the optimization of the parameters in roller drafting.     

Windthrow resistance of apple trees grafted in an orchard

Pull-down tests were conducted for apple trees grafted in an orchard and for support posts in order to discuss the failure mode in windthrow damage, the effect of rootstock types on the uprooting strength, and the reinforcing effect of support posts on young trees. The test samples were ten mature trees (20–23 years old) of three varieties grafted on two types of rootstocks, three young trees (7 years old) grafted on dwarf rootstocks, and nine support posts of larch logs and steel pipes. The failure modes were found to be uprooting for mature trees and rootstock breakage for young trees. The uprooting strength of apple trees was considerably smaller than the uprooting strength of forest trees reported in previous studies. However, the windthrow resistance of the apple trees with respect to the critical wind velocity was estimated to be sufficient despite their low uprooting strength because of their small height. Young trees should be supported with wooden posts for a few years after grafting so that they acquire sufficient windthrow resistance. Part of this study was published in the report for the Grant-in-Aid for Collaborative Research by NOASTEC (No. H17-kyo-048)     

Crop species present different qualitative types of response to N deficiency during their vegetative growth

Crops respond to N deficiency through a reduction in resource capture and/or resource use efficiency. The objective of this paper is to examine whether differences in this response pattern are associated with either metabolic group (C₃ vs. C₄) or botanical classification (mono- vs. dicotyledons). Hereto, we analysed the effect of N deficiency on the relationships between N uptake, LAI, and biomass accumulation, for maize, sorghum, wheat, canola, tall fescue, and sunflower, grown in experiments in either France or Australia. Maize and tall fescue maintained LAI per unit biomass (measure of resource capture) at the expense of N uptake per unit LAI (measure of resource use efficiency). Wheat and canola had the opposite response, whereas sunflower and sorghum were intermediate. In general, C₄ species reduced N uptake per unit LAI more than C₃ species. Species differences in the effect of N deficiency on resource use efficiency were associated with differences in the SLN or in the N storage capacity of the stems. For wheat, canola, and tall fescue, SLN declined with increasing LAI under high N conditions, and the minimum crop SLN under N deficiency was only marginally lower than under high N conditions. For sorghum, sunflower, and maize, crop SLN under high N changed little with increasing LAI, but the minimum crop SLN under N deficiency was considerably lower than under high N. Sorghum and maize were the only species that substantially decreased stem N uptake per unit LAI under N deficiency. Overall, our data suggest that C₃ species are better able to maintain resource use efficiency under N stress than C₄ species, and a survey of literature suggests this may be because in C₄ species, the critical SLN for radiation use efficiency is higher than the critical SLN for leaf expansion, whereas the opposite is the case for C₃ species. We hypothesise that species differences in response to N deficiency could be associated with these differences in critical SLN, which in turn could be a consequence of the lower photosynthetic nitrogen use efficiency of C₃ crops.     

两个新籼稻光温敏核不育系的育性转换特性研究

为了研究新育成的水稻光温敏雄性不育系H61S、H69S的育性转换特性,于2005~2006年在湛江进行了分期播种试验和人工控制光温试验,结果表明：（1）温度是引起两个光温敏不育系育性转换的最主要的原因,光照时数对不育系育性影响不显著。（2）H61S、H69S的育性温度敏感期分别为抽穗前19~10d和20~10d,最敏感期均为抽穗前17~13d,与对照培矮64相似。（3）当不育系由不育转为可育,可育花粉率达1%时,H61S、H69S和对照培矮64S的育性转换临界温度分别为24.2℃、25.3℃、26.1℃。（4）两个不育系在湛江自然播种条件下都有较长的稳定不育期和较高的自交结实率,育性转换期均比对照培矮64S短,可以安全制种,也可繁殖,但适宜繁殖的抽穗期范围窄。     

浅析两系“龙凤胎”—x186

2003年在01-124稻田里发现不育株36-20S后,先后两年南北两地高低温条件下未得到不育株种子,因而采用"逐代展开法"保留其不育基因。2011年9月,发现其杂交后代不育株率高达42%。利用冬季南滨变温幅度大的条件,观察x186不育株稻茬、可育株单株和同代原种不育株的育性。结果表明x186G1S、x186HS是温敏不育系,起点温度为21～22℃,x186G2S、x186-1S、x186-2S是反温敏不育系,临界温度为25～26℃。x186同时含有温敏型不育基因和反温敏不育基因,因而称作"龙凤胎"。同时选育育性类型截然不同的两系不育系,既拓宽时空,又便于制、繁种。反温敏不育系的选育及应用,将为两系法杂交粳稻育种的发展和杂交粳稻的推广应用带来变革,x186便是北方早粳稻区两系法育种的拐点。     

膜下滴灌棉花关键生育期不同灌水量、灌水次数对其生长、产量及水分利用效率的影响

通过2004年棉花生长季田间试验,我们研究了膜下滴灌棉花关键生育期不同灌水量和灌水次数对其生长、产量及水分利用效率（WUE）的影响,旨在建立河北南部棉区滴灌条件下的优化灌溉模式,提高作物水分利用效率,达到节水增产目的。试验结果表明：不同灌水方式对棉花产量和水分利用效率的影响具有显著差异,棉花需水关键期花铃期分2次少量灌水处理,每次灌水量10．42mm,明显优于两次多量灌水和集中一次灌溉等其他处理,产量和WUE最高,分别高达4929．0kg／hm^2和0．98kg／m^3,具有明显的节水增产效益。