麦油稻轮作秸秆还田与施氮对水稻光合特性及产量的影响

以宜香优2115为材料,采用二因素裂区设计:主区设小麦或油菜秸秆全量翻埋还田(M_1)和秸秆不还田对照(M_0);副区设4个氮肥管理,不施氮(N_0),基肥、分蘖肥、促花肥、保花肥氮肥施用比例为10∶0∶0∶0(N_1),基肥、分蘖肥、促花肥、保花肥氮肥施用比例为3∶3∶2∶2(N_2),基肥、分蘖肥、促花肥、保花肥氮肥施用比例为2∶2∶3∶3(N_3),研究秸秆还田和氮肥管理对直播稻的光合特性、干物质积累及产量的影响。结果表明:麦–稻或油–稻轮作下,氮肥管理对直播稻主要生育时期的干物质积累、光合特性及产量均存在显著或极显著的调控效应,秸秆还田显著影响水稻拔节期、齐穗期的叶面积指数(LAI)及群体干物质积累,同时油–稻轮作下其调控效应高于麦–稻轮作模式。秸秆不还田时,配合N_3施肥方式,可有效提高直播稻结实期剑叶净光合速率、SPAD值和叶面积指数,延缓叶片衰老,且在拔节期至成熟期间保持较高的群体生长率,干物质积累优势明显;秸秆还田下,配以基肥、分蘖肥、促花肥、保花肥氮肥施用比例为3∶3∶2∶2的管理模式,麦茬或油茬直播稻群体构建合理,结实期剑叶光合能力强,有效穗、每穗粒数较多,表现高产,产量最高可达10 090、10 693 kg/hm~2。综合分析,麦–稻或油–稻轮作下秸秆还田,配合基肥、分蘖肥、促花肥、保花肥氮肥施用比例为3∶3∶2∶2的氮肥管理模式,能实现直播稻的高产稳产。     

广西银荷木林分类的研究

银荷木林是广西亚热带黄壤山地常见的一类常绿阔叶林 .它是在常绿阔叶林遭受破坏后 ,在保护较好的情况下 ,从演替系列群落顺向演替恢复为常绿阔叶林的一个先期类型 ,并向以栲属林木为主的类型变化 .该文对广西银荷木群系作了较详细的研究 ,划分和论述了 1 0个群丛的基本特点和演替趋向 ,可供进一步研究退化生态系统的恢复和重建参考     

黄瓜耐热性与其叶片、根系和花粉性状关系的研究

在提出一种黄瓜营养生长耐热性评价方法的基础上,研究黄瓜耐热性与其叶片、根系和花粉性状的关系。结果表明：黄瓜营养生长的耐热性是高温下黄瓜产量形成的重要生理基础,花粉耐热性不能作为黄瓜耐热材料的筛选指标。高温下黄瓜叶片厚度、叶片栅栏组织厚度、叶片温度、气孔导度、蒸腾速率和根系干重与黄瓜营养生长耐热性呈显著线性相关,表明蒸腾降温是黄瓜营养系统避免高温伤害的重要机制。     

不同外源激素对糜子成穗及产量的影响

研究不同种类外源激素对糜子成穗及产量的影响。用5种外源激素在糜子3~4叶期喷施,连续处理2次,喷清水为对照。记录糜子苗期基本苗数、拔节期总茎数、成熟期穗数等性状,用统计软件SPSS 17.0进行统计分析。结果表明,施用脱落酸（ABA）能够显著降低糜子的分蘖数,施用赤霉素（GA₃）、吲哚乙酸（IAA）、矮壮素（CCC）也能减少糜子分蘖数,但是与对照差异不显著,施用多效唑（PP₃₃₃）对糜子分蘖数没有明显影响;施用GA₃、IAA、CCC能够增加分蘖穗数,而ABA、PP₃₃₃降低分蘖穗数;各处理分蘖成穗率都较对照高,ABA处理分蘖成穗率为最高达到25.20%;ABA处理主茎穗占比较对照增加,分蘖穗占比降低;GA₃、IAA、CCC处理主茎穗占比相对于对照降低,分蘖穗占比增加,PP₃₃₃处理与对照相近;5种外源激素对糜子产量的影响差异显著,施用ABA产量最高,可能与主茎穗占比高和分蘖成穗率高有关系。在糜子3~4叶期喷施5种外源激素,对糜子有显著作用的是ABA,主要表现在ABA能够降低糜子分蘖数,保证了主茎的成穗数量,增加了分蘖成穗率,从而提高了糜子产量。     

棉花地上部形态建成的光温模型

以不同株型棉花品种为研究对象,基于“同类相似性”原理,借助数学建模和统计分析方法,系统分析光温生态因子对棉花叶片长、宽,叶柄长、粗,主茎节间长、粗,果节长、粗,蕾铃高、直径等形态指标的影响,量化温、光因子与棉花各器官形态建成的关系,构建了基于GDD (growing degree day)和Logistic方程的棉花形态建成光温模型。利用独立的试验数据对模型进行了检验,结果表明,棉花主茎叶片的长度和宽度、叶柄长度、主茎节间的长度和粗度、果枝叶片的长度和宽度、叶柄长度、果节的长度和粗度、蕾铃高度和直径的RMSE值分别为0.48、0.65、0.53、0.09、0.02、0.55、0.28、0.23、0.14、0.17、0.20和0.11 cm。显示棉花器官形态指标的模拟值与检验值具有较好的吻合度,说明模型具有良好的预测性和描述性。     

含蜡原油管道胶凝形成机理研究进展

介绍了国内外献中对含蜡原油胶凝形成机理的研究成果。研究结果表明，在含蜡原油管道中，当油温低于浊点时，易在管壁处形成一层类似固体的凝胶物质。含蜡原油管道胶凝的形成主要受热历史和剪切历史的影响，胶凝湿度随冷却速度的减小而降低，随剪切应力的增大而降低，而浊点与冷却速度和剪切应力无关。在环境湿度高于油温的情况下， 即便油温低于浊点湿度，含蜡原油也不会形成胶凝。由于胶凝具有类似固体的机械特性，因此冷却速率越快，石蜡晶体越小，越多，屈服应力也越大，胶凝屈服应力取决于蜡晶的大小和数目。     

Progress and Yield Bottleneck of Aerobic Rice in the North China Plain: A Case Study of Varieties Handao 297 and Handao 502

Aerobic rice has been considered a promising rice cultivation system as water scarcity is increasing in the world. This article summarizes the advances in aerobic rice management researches in the North China Plain, focusing on yield formation and its bottleneck. High-yielding and good-quality aerobic rice varieties adapted to aerobic soil conditions have been released officially and adopted by farmers in North China. The varieties Handao 502 and Handao 297 have been recognized as the most promising varieties reaching a yield level ranging 3.5-5.0 t ha-1 with 450-650 mm water input. Compared with lowland rice, water input in aerobic rice was more than 50% lower, and water productivity was 60% higher. Researches on responses of rice cultivars to nitrate nitrogen （N） and ammonium N supplied at early growth stages provided the first evidence for a preference of aerobic rice HD297 for nitrate N supply, compared with the lowland rice variety. Zinc uptake studies demonstrated that introduction of aerobic rice system on calcareous soils may increase zinc deficiency problems. Sink size was identified as the limitation of aerobic rice yield, because its spikelet number m-2 was too low （20000-24 000） compared with the lowland rice. For future research, more attention is suggested to be paid to yield formation focusing on effects of water regimes on tiller dynamics. Understanding of nutrient uptake and response to fertilization effects are also urgently required to establish optimized crop management technology. Additionally, alternative cropping systems based on aerobic rice should be established, and key sustainability and environmental impact issues in the systems need to be identified.     

Influence of Soil Drought on Plant Growth, Assimilation and Dissimilation of CO2 and Accumulation of Photosynthates in Field Bean (Vicia faba L. minor) During Pod Formation and Rapid Pod Growth

Field bean planes cultivar Nadwiślański were submitted to soil drought (30 % of field soil water capacity) for 5 days at the stage of pod formation (A) and of rapid pod growth (B) and then exposed for 20 minutes to ¹⁴CO₂. Radioactivity of leaves, stems, roots, and pods or pod shells and seeds was measured 1, 5, 24 and 48 hours after exposition.
In both stages soil drought reduced by about five times total CO₂ assimilation, mainly owing to lower activity of the photosynthetic apparatus and also, though less so, to reduced leaf growth. Photosynthetic activity referred to the dry weight of the leaves dropped to 22-35% of controls. Accumulation of photosynthetates in generative organs was much less depressed than ¹⁴CO₂ assimilation. 48 hours after exposition to ¹⁴CO₂ of drought treated plants, the contents of ¹⁴C of pods in phase A, and seeds in phase B, amounted to respectively 24% and 36% of assimilated ¹⁴C and equalled 91.5% and 74% of the corresponding values for controls.
The progressive decline of radioactivity in leaves and stems after ¹⁴CO₂ exposition was distinctly correlated to the rise of radioactivity of generative organs both in soil drought treated plants and in controls. Slightly lower values of correlation coefficients in drought treated plants may indicate impairment under drought conditions of synchronization in processes of unloading and accumulation of assimilates.
In plants drought treated in phase A the ability to dissimilate ¹⁴C was reduced to about 59% of that in controls, but when drought was applied in phase B, dissimilation rate was about three times as high.     

Dynamic climate control; an optimization study for earliness of cucumber production

The culture of a cucumber crop can be divided into two stages: growth of young plants until flowering, and fruit production. The first stage should be as short as possible to minimize the costs during the vegetative phase. In the present study, a simple optimization model was tested. The model quantifies the instantaneous effect of environmental factors on earliness of production using the number of leaves as a characteristic parameter related to the onset of the production stage. The temperature in the glasshouse was optimized by maximizing the difference between the rate of economic production and the rate of energy consumption.In a glasshouse experiment, it appeared that effects of light and temperature on the leaf unfolding process differ. Whereas the leaf unfolding rate responds rapidly to a change in temperature, changes of light intensity give rise to a considerably delayed response. The effect of light intensity during the time prior to planting appears to be of significant importance to the leaf unfolding rate in the subsequent period from planting until flowering.