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1.
Dry Matter Production, CO2 Exchange, Carbohydrate and Nitrogen Content of Winter Wheat at Elevated CO2 Concentration and Drought Stress
Methods of mathematical modelling and simulation are being used to an increasing degree in estimating the effects of rising atmospheric CO2 concentration and changing climatic conditions on agricultural ecosystems. In this context, detailed knowledge is required about the possible effects on crop growth and physiological processes. To this aim, the influence of an elevated CO2 concentration and of drought stress on dry matter production, CO2 exchange, and on carbohydrate and nitrogen content was studied in two winter wheat varieties from shooting to milk ripeness. Elevated CO2 concentration leads to a compensation of drought stress and at optimal water supply to an increase of vegetative dry matter and of yield to the fourfold value. This effects were caused by enhanced growth of secondary tillers which were reduced in plants cultivated at atmospheric CO2 concentration. Analogous effects in the development of ear organs were influenced additionally by competitive interactions between the developing organs. The content and the mass of ethanol soluble carbohydrates in leaves and stems were increased after the CO2 treatment and exhausted more completely during the grain filling period after drought stress. Plants cultivated from shooting to milk ripeness at elevated CO2 concentration showed a reduced response of net photosynthesis rate to increasing CO2 concentration by comparison with untreated plants. The rate of dark respiration was increased in this plants.  相似文献   
2.
A field experiment was conducted to find out the critical physiological stages of irrigation schedules inducing better growth, physiological efficiency and seed yield potential of berseem ( Trifolium alexandrinum L., Var. S-99-1). For this purpose eight irrigation treatments were made comprised of four treatments of three irrigation (W1, W2, W3 and W4), three treatments of four irrigation (W5, W7 and W8) and one treatment of five irrigation (W6) at various physiological stages i. e. regeneration, flower initiation, full bloom, seed initiation and advance seed development stage.
Thus based on the experimental results the physiological role of watering in berseem seed production could be discussed as:
With-holding of irrigation either at regeneration or at full bloom stage developed potential water stress in plants as indicated by high proline content of irrigation treatments — W4, W1 and W7; and further brought out disturbance on the formation of carotene, synthesis of water soluble sugar and translocation of sugar towards reproductive organs during grain development stage. These stresses adversely affected the plant growth and flowering behaviour. The irrigation at seed initiation stage increased the seed yield. Continuous irrigation did not appear to be useful. Thus it can be concluded that irrigation at three critical physiological stages i. e. regeneration, full bloom and seed initiation was found to be essential for obtaining potential seed yield of berseem.  相似文献   
3.
Root length of Holcus lanatus L. declined rapidly with increasing lead and zinc concentrations in nutrient solution. In all used Pb and Zn concentrations root growth of genotypes coming from a Pb-Zn mine area, was greater than that of the control, suggesting that these genotypes evolved tolerance to Pb and Zn.
Negative correlation was also observed between chlorophyll content and increased heavy metal concentrations. The greater chlorophyll content found in tolerant genotypes, in different Pb and Zn concentrations, in comparison with the control, could be served to distinguish tolerant and non-tolerant genotypes.  相似文献   
4.
In this study, the effects of nitrogen (N) rate (60, 120, 180 and 240 kg N ha?1 applied in three equal dressings at seeding and after the first and second cuttings) and stubble height (7, 14 and 21 cm) on the dry matter (DM) yield, crude protein (CP) content, and CP yield of a sorghum–sudangrass hybrid [Sorghum bicolor (L.) Moench × Sorghum sudanense (Piper) Stapf., cv. Pioneer 988] in the three‐cut system was investigated. The N rate had no significant effect in the first and third cuttings, but in the second cutting DM yields increased significantly with increase in N rate. The highest yield of 9.1 t ha?1 was obtained with 80 kg N ha?1 for the average of 2 years at the second cutting, but no significant difference was found among the 40, 60 and 80 kg N ha?1 rates. CP content and yield were not significantly affected by N rate at the first and third cuttings, but CP content and yield were significantly affected by application of N at the second cutting. Stubble height had a significant effect on CP content at the third cutting. However, it had no significant effect on CP content at the first and second cuttings. Stubble height had a significant effect on the CP yield at the first cutting, but no significant effect on CP yield at the second and third cuttings.  相似文献   
5.
6.
土壤水热参数是研究土壤水热传输的基本物理参数。当前热脉冲探针法(HPP)可同步测定土壤水热参数,但该方法仅限于在点尺度下测定。与其具有相同理论基础的加热光纤法(SPHP-DTS),可将测定尺度增大至田间千米尺度,但其测定精度尚未得到有效验证。为了探知SPHP-DTS法的误差,本研究进行了SPHP-DTS法与HPP法测定土壤水热参数的对比试验。结果表明,以HPP为标准,加热光纤法测定热导率的精度RMSE为0.13 W?m-1?℃-1。SPHP-DTS法测定的热导率显著高于HPP法,主要原因在于加热光纤时产生的温度效应。通过热导率法测定土壤含水率时,在热导率测定误差的影响下,SPHP-DTS法的测定精度明显低于HPP法。SPHP-DTS法测定土壤水热参数的其他误差来源包括光纤与土壤之间多个界面的接触热阻、光纤的温度敏感性、噪音干扰以及温度梯度驱动下的水分迁移。本研究可为SPHP-DTS法提升土壤水热参数测定精度提供理论参考。  相似文献   
7.
西瓜可溶性固形物含量近红外透射检测技术   总被引:9,自引:4,他引:5  
设计的近红外透射式西瓜可溶性固形物含量(SSC)检测系统主要包括光纤光谱仪、光纤透射附件、数据采集卡以及自制光源。对50个麒麟瓜SSC进行了预测试验,采用主成分回归和偏最小二乘回归法分别建立了样品的原始光谱、一阶微分光谱、二阶微分光谱和SSC的预测模型,结果表明偏最小二乘回归法建立的模型具有较高的相关性,相关系数为0.951,均方根校正误差0.347,均方根预测误差0.302,样本真实值与预测值的相关系数为0.910。  相似文献   
8.
为对大田冬小麦叶片氮素含量(LNC)进行快速、准确及无损监测,通过在江苏省泰州泰兴市、盐城大丰区和南通如皋市布设冬小麦遥感监测大田试验,在获取试验样点冬小麦冠层红光波段反射率(REDref)、近红外波段反射率(NIRref)和计算的十个光谱指数(RVI、NDVI、DVI、SAVI、OSAVI、MSR、RDVI、EVI2、NLI和SVI)基础上,将12个遥感光谱指标与冬小麦LNC进行相关分析,选出与LNC相关性较好的作为模型输入变量,构建基于BP神经网络的冬小麦LNC估测模型, 并利用GF-6/WFV卫星遥感影像对县域冬小麦LNC的空间分布开展监测。结果表明,12个遥感光谱指标与冬小麦LNC之间存在不同程度的相关性,其中NDVI、RVI、MSR、OSAVI和NLI与冬小麦LNC的相关性较好(相关系数不低于0.65)。将优选的5个遥感光谱指标作为模型输入变量,构建基于BP神经网络的冬小麦LNC估测模型(LNC-BPEM),模型的估测精度r2=0.866,RMSE=0.246%,ARE=12.9%。将冬小麦LNC-BPEM估测模型和GF-6/WFV影像结合对县域冬小麦LNC的空间信息监测,获得了如皋县域冬小麦LNC的空间分布特征,该区域冬小麦LNC范围在0.9%~2.0%(长势正常)的种植面积为29 693.3 hm2,占冬小麦总种植面积的74%。这说明利用GF-6/WFV卫星的多个遥感光谱指标与神经网络结合建模可有效估测县域大田冬小麦叶片氮素含量。  相似文献   
9.
【目的】利用两种外源硅肥材料开展试验,研究外源硅对土壤重金属Cd有效性以及稻谷Cd含量的影响。【方法】以硅胶(分子式mSiO2.nH2O,含量98%以上)、液体硅肥(SiO2浓度≥23%)作为外源硅肥材料,通过在重金属镉Cd超标稻田土壤施用硅胶,在水稻分蘖期、孕穗期喷施液体硅肥,研究硅钝化稻田土壤重金属Cd有效性及降低稻谷Cd含量。【结果】施用硅胶达到100kg/667m2对降低土壤有效Cd含量有极显著效果,表明稻田施用硅胶可以钝化土壤重金属Cd有效性;施用硅胶达到100kg/667m2对降低稻谷Cd含量有显著效果,施用硅胶再配合喷施液体硅肥时,对降低稻谷Cd含量有极显著效果;施用硅胶、液体硅肥对提高稻谷产量有显著作用。【结论】基施硅胶配合喷施液体硅肥,对钝化土壤重金属Cd有效性,降低稻谷Cd含量,提高稻谷产量具有显著效果。  相似文献   
10.
为合理预测意大利蝗Calliptamus italicus的种群动态,分别用1%(对照)、4%和7%氮含量的食物饲喂意大利蝗5龄蝗蝻,测定不同氮含量食物处理后意大利蝗5龄蝗蝻的生长速率,羽化后7 d的体长、股节长、胫节长、翅长、翅宽、体重及羽化后1、7、13和19 d的卵巢面积。结果显示,4%氮含量食物处理试虫的生长速率最大,分别较1%和7%氮含量处理的增加了88.02%和109.33%;4%和7%氮含量食物处理后,意大利蝗成虫的后翅宽和体重均显著高于对照;羽化后7 d,不同氮含量食物处理的意大利蝗卵巢面积出现显著差异,羽化后19 d,4%氮含量食物处理的卵巢面积显著高于其他2个处理。表明中等氮含量(4%氮含量)适宜意大利蝗生长。  相似文献   
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