滴灌加工番茄叶面积、干物质生产与积累模拟模型

以生理发育时间为时间尺度,建立了基于生理发育时间(PDT)的加工番茄叶面积指数(LAI)、比叶面积(SLA)模拟模型,并将叶面积指数模型与基于生理生态过程的光合作用和干物质生产模型相结合,构建了滴灌加工番茄干物质生产与积累的模拟模型。结果表明:PDT法对加工番茄叶面积指数(LAI)与1∶1直线间的决定系数R2、根均方差(RMSE)和模型效率指数(ME)分别为0.926 5、12.87%、0.972 4;SLA法模拟叶面积指数的预测结果与1∶1直线间的R2、RMSE和ME分别为0.675 8、42.24%、0.712 4。本模型对加工番茄地上部干物质量的预测结果与1∶1直线间的R2、RMSE和ME分别为0.990 3、11.91%、0.990 1;而SLA法对加工番茄地上部干物质量的预测结果与1∶1直线间的R2、RMSE和ME分别为0.895 6、31.29%、0.750 4。与SLA法相比,PDT法在改善加工番茄叶面积指数预测精度的同时亦提高了干物质量的预测精度。     

堆肥预处理对松木屑厌氧发酵的影响

针对目前针叶类林木松树厌氧发酵前预处理效果差、成本高的问题,在添加食品废弃物的条件下,研究好氧堆肥方法对松木屑(6.35 mm、9.53 mm和12.70 mm)和食品废弃物混合物料的预处理效果,以及对后续干式厌氧发酵过程的影响。研究结果表明,好氧堆肥过程对松木屑的预处理效果明显,但随着松木屑粒径的增大预处理效果降低;经堆肥预处理后物料的厌氧发酵原料的VS产气率均维持在199~215 L/kg范围内,约为未预处理组的1.4倍,而且发酵后物料中的VFA总量均维持在24.5左右,约为未堆肥预处理组的1.5倍,后续产气潜力更大。     

旱作多功能精密穴播轮的研究

通过旱作多功能精密穴播轮工作机理的研究,建立了容种、充种、清种、成穴过程相关数学模型,揭示了穴播轮转速、容种高度对播种质量的影响规律。     

旱涝交替胁迫对水稻荧光参数与光合特性的影响

为探明控制灌排条件下旱涝交替胁迫对水稻不同生育阶段荧光参数和光合特性的影响,以农田水位为调控技术指标,采用蒸渗测坑进行水稻栽培试验,在分蘖期、拔节孕穗期、抽穗开花期、乳熟期分别设置先旱后涝胁迫（HZL）、先涝后旱胁迫（LZH）2种旱涝交替胁迫模式,测定叶片相对叶绿素含量（SPAD）、主要荧光参数及光合指标的变化。结果表明,旱涝交替胁迫会减少SPAD,其中HZL处理产生的抑制作用更强;分蘖期、拔节孕穗期旱涝交替胁迫光能转化效率、光化学淬灭系数、最大潜在电子传输速率、光饱和点、净光合速率、潜在水分利用效率等荧光参数和光合指标可以恢复甚至超过对照水平,而在抽穗开花期、乳熟期产生不可逆的影响;旱涝交替胁迫下蒸腾速率、气孔导度分别在分蘖期、乳熟期受到抑制,拔节孕穗期得到促进;HZL处理提高了非光化学淬灭系数,其他主要荧光参数和光合指标HZL低于LZH处理。水稻分蘖期、拔节孕穗期LZH处理对光合作用的补偿作用更大,抽穗开花期、乳熟期HZL处理对光合作用的抑制作用较LZH处理更明显,因此,在水稻生育后期应尽量避免重度的旱涝交替胁迫,尤其要避免发生旱涝急转。     

易涝易渍农田地下水动态特征

地下水动态是评价易涝易渍农田生产稳定性的重要指标,基于湖北四湖流域大量调查观测资料对此进行了研究。结果表明,易涝易渍农田地下水位存在明显的年、季差异,呈现出一定的波动性,在不同季节以及不同水平年间波动幅度不大,绝对偏差一般只有1 0~2 0 cm左右,最大不超过4 0 cm,地下水位呈现出在高水位上波动的特点;从微地形地貌看,沿江地势较高的农田其地下水平均埋深和地下水位波动与地势低洼的滨湖农田明显不同,前者明显大于后者。在较大尺度上当降水很接近时,农田地下水埋深随微地貌分异并不显著;对于水网密织的南方平原湖区,农田地下水位变化与周边水体相联系并受其影响,在农田涝渍防治中必须处理好农田与周边水体的关系。     

甘蔗叶干法厌氧发酵工艺研究

为实现甘蔗叶的能源化利用,采用干法厌氧发酵方法研究发酵原料总固体含量为20%时,不同接种量、草粪比以及发酵温度对甘蔗叶产气量和产甲烷的影响。结果表明：接种量在30%和40%时发酵可以正常启动,接种量为40%时总产气量最高,但发酵后期甲烷含量下降很快;草粪比为1∶1和2∶1时总产气量高,甲烷含量均在60%以上,产气效果明显好于草粪比为1∶0的处理组;发酵温度为35℃时,总产气量和甲烷含量最高,发酵温度为30℃和40℃时总产气量相差不大。甘蔗叶干法厌氧发酵产沼气效果较好的工艺参数为：接种量30%、草粪比1∶1和发酵温度35℃。各处理组在甲烷含量达到最高值之前,甲烷含量与发酵时间之间呈现很强的线性相关性。产气高峰过后,虽然日产气量明显下降,但气体中甲烷含量下降幅度不大。     

灰色系统理论和可公度性理论在大连市涝灾预测中的应用

采用大连市1951-2006年的降水资料,应用Z指标法得出大连市1951-2006年的涝灾年份.在这些数据分析的基础上,应用了三元、四元、五元可公度法分别预测了大连市的下一次可能发生的涝灾的年份.同时根据灰色系统理论建立灰色GM(1,1)模型对大连市未来的涝灾年份做出预测.结果表明:两种方法都能较好的应用于大连市涝灾研...     

Water management options based on rainfall analysis for rainfed maize (Zea mays L.) production in Rushinga district, Zimbabwe

Maize (Zea mays L.), the dominant and staple food crop in Southern and Eastern Africa, is preferred to the drought-tolerant sorghum and pearl millet even in semi-arid areas. In semi-arid areas production of maize is constrained by droughts and poor rainfall distribution. The best way to grow crops in these areas is through irrigation, but limited areal extent, increasing water scarcity, and prohibitive development costs limit the feasibility of irrigation. Therefore, there is need for a policy shift towards other viable options. This paper presents daily rainfall analysis from Rushinga district, a semi-arid location in Northern Zimbabwe. The purpose of the rainfall analysis was to assess opportunities and limitations for rainfed maize production using 25 years of data. Data was analysed using a variety of statistical methods that include trend analysis, t-test for independent samples, rank-based frequency analysis, Spearman's correlation coefficient and Mann-Whitney's U test. The results showed no evidence of change in rainfall pattern. The mean seasonal rainfall was 631 mm with a standard deviation (SD) of 175 mm. December, January and February consistently remained the major rainfall months. The results depicted high inter-annual variability for both annual and seasonal rainfall totals, a high incidence of droughts ≥3 out of every 10 years and ≥1 wet year in 10 years. Using the planting criteria recommended in Zimbabwe, most of the plantings would occur from the third decade of November with the mode being the first decade of December. This predisposes the rainfall to high evaporation and runoff losses especially in December when the crop is still in its initial stage of growth. On average 5 to more than 20 days dry spells occupy 56% of the rainy season. Seasonal rainfall exhibited negative correlation (P < 0.001; R = −0.746) with cumulative dry spell length, and wet years were free from dry spells exceeding 20 days. The most common dry spells (6-10 days), are in the range in which irrigated crops survive on available soil water. Therefore, they can be mitigated by in situ rainwater harvesting (RWH) and water conservation. The potential evapotranspiration of a 140-day maize crop was estimated to be 540 mm. Consequently, short season maize cultivars that mature in less than 140 days could be grown successfully in this area in all but drought years. However, sustainable maize production can only be achieved with careful management of the soil as a medium for storing water, which is essential for buffering against dry spells. To this end soil restorative farming systems are recommended such as conservation farming, in situ RWH techniques for dry spell mitigation and a cropping system that includes drought-tolerant cereal crops as for example sorghum and pearl millet, and perennial carbohydrate sources as for example cassava to provide stable crop yields.     

水浸提沙棘果渣总黄酮工艺研究

本文提供了水浸提沙棘果渣总黄酮的工艺流程,主要技术参数为：将新榨出的沙棘果渣湿粉碎20～30目、沸水入锅、煮沸浸提进行预处理;提取的最优工艺组合是温度90℃,固液比1：10,提取次数4次,浸提时间为45min。洗脱的最佳工艺组合为乙醇浓度为40％、乙醇用量为8倍量、洗脱温度为25℃。     

Effect of irrigation amounts applied with subsurface drip irrigation on corn evapotranspiration, yield, water use efficiency, and dry matter production in a semiarid climate

Quantifying the local crop response to irrigation is important for establishing adequate irrigation management strategies. This study evaluated the effect of irrigation applied with subsurface drip irrigation on field corn (Zea mays L.) evapotranspiration (ETc), yield, water use efficiencies (WUE = yield/ETc, and IWUE = yield/irrigation), and dry matter production in the semiarid climate of west central Nebraska. Eight treatments were imposed with irrigation amounts ranging from 53 to 356 mm in 2005 and from 22 to 226 mm in 2006. A soil water balance approach (based on FAO-56) was used to estimate daily soil water and ETc. Treatments resulted in seasonal ETc of 580–663 mm and 466–656 mm in 2005 and 2006, respectively. Yields among treatments differed by as much as 22% in 2005 and 52% in 2006. In both seasons, irrigation significantly affected yields, which increased with irrigation up to a point where irrigation became excessive. Distinct relationships were obtained each season. Yields increased linearly with seasonal ETc (R² = 0.89) and ETc/ETp (R² = 0.87) (ETp = ETc with no water stress). The yield response factor (ky), which indicates the relative reduction in yield to relative reduction in ETc, averaged 1.58 over the two seasons. WUE increased non-linearly with seasonal ETc and with yield. WUE was more sensitive to irrigation during the drier 2006 season, compared with 2005. Both seasons, IWUE decreased sharply with irrigation. Irrigation significantly affected dry matter production and partitioning into the different plant components (grain, cob, and stover). On average, the grain accounted for the majority of the above-ground plant dry mass (≈59%), followed by the stover (≈33%) and the cob (≈8%). The dry mass of the plant and that of each plant component tended to increase with seasonal ETc. The good relationships obtained in the study between crop performance indicators and seasonal ETc demonstrate that accurate estimates of ETc on a daily and seasonal basis can be valuable for making tactical in-season irrigation management decisions and for strategic irrigation planning and management.