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1.
为了确定与棉铃虫虫害发生相关显著的气象因子，并据此做出棉铃虫发生情况的合理预报，分析了河北省衡水市故城县2000―2017年的气象资料和棉铃虫虫情资料。得出：衡水棉铃虫卵的始见日最早为5月24日，最晚为8月22日；2代、3代、4代卵盛期分别为6月13日－7月1日、7月18日－8月4日和8月17日－9月14日；棉铃虫虫害主要发生在6－8月；棉铃虫的发生主要和气温、地温和相对湿度有关。利用逐步回归方法建立了棉铃虫发生的预报预测模型并进行了回测检验，相应预报模型对2代、3代、4代百株累计卵量的预报平均相对误差分别为21.1%、20.7%、29.9%，对各代卵的等级预报准确率分别为94.4%、83.3%、77.8%。 相似文献
2.
对 39个食用大麦的株高 (x1)、平均穗长 (x2 )、基本苗 (x3)、最高苗 (x4 )、有效穗 (x5)、穗粒数 (x6 )、千粒重 (x7)、全生育期 (x8)和公顷产量 (y)之间进行多元回归分析。结果如下 :(1)x5、x6 、x7对 y的贡献达极显著水平 ,它们和 y之间的直线回归方程为 y =730 8 84 14 +187 92 4 0x5+10 0 5 5 5 1x6 +10 4 3931x7(F =10 0 30 0 ,R =0 94 6 5 ,根据这一方程可对四棱食用大麦的产量进行预报 ;(2 )八个农艺性状对产量贡献大小的顺序为 :有效穗 >穗粒数 >千粒重 >基本苗 >全生育期 >株高 >最高苗 >平均穗长 ,因此在食用大麦的育种实践中 ,应把提高有效穗、穗粒数作为主要育种目标 ,千粒重次之。 相似文献
3.
为掌握汉中市小麦条锈病流行规律,提高病害测报的科学性和准确性,采用DPS数据处理系统,对多年来汉中市小麦条锈病测报资料进行了主导因素分析,筛选出影响发病程度的主要因子包括小麦感病品种种植比例(x1)、秋苗病田率(x2)、秋苗单位面积平均病叶数(x3)、1月份平均气温(x6)、上年11月份降雨量(x11)、早春病田率(x18)、3月中旬病田率(x19),与发生程度(y)进行逐步回归分析,建立了发病程度预测模型:y=-6.354 7+0.084 0x1+0.022 8x3+0.662 8x6+0.020 9x11,R2=0.968 7。拟合预测符合率为92.31%,相对误差8.96%。利用预测模型对2014-2016年汉中市小麦条锈病进行预测,预测的病级分别为2.93、3.21、1.92,与2014、2015、2016年发生的实际病级3、3、2相吻合。此模型可应用于生产中小麦条锈病的测报。 相似文献
4.
基于自适应增强的BP模型的浙江省茶叶产量预测 总被引：1，自引：0，他引：1
本文采用1999—2018年浙江省59个县市的茶叶产量数据和地面气象要素驱动数据,提出了基于产量等级因子的自适应增强的反向传播（BP）神经网络模型的茶叶产量预测机制。首先分析提取了种植面积、年平均气温、3—7月的平均相对湿度、年平均相对湿度等11个影响因子,然后构建浙江省茶叶产量预测模型。试验结果表明,基于产量等级因子的自适应增强的BP模型算法相关系数达到0.893,相对误差的平均值和方差分别为0.187和0.136。在试验数据选取方面,相较于距离预测年份较远的数据,采用临近预测年份的数据,预测精度较高。根据本研究的茶叶产量预测机制,建立了浙江省茶叶产量预测误差空间分布图,其中1级优势区的平均误差为18.32%,2级次优势区为16.73%,3级一般产区为22.69%。预测模型能够实现浙江省各县市的茶叶产量预测,对茶叶生产的宏观管理具有一定指导意义。 相似文献
5.
6.
为探讨基于等距拆分和随机森林算法用于皖北小麦始花期气象预报的可行性,利用1980-2019年皖北地区7个农业气象观测站的冬小麦始花期原位观测物候数据和平行观测的气象数据,采用相关系数法,筛选影响始花期早迟的特征变量,采用有序等距离抽样法,拆分出训练集和测试集。基于随机森林算法（RF）,从4月10日到4月15日,每日训练1个预报模型,实现小麦始花期逐日滚动气象预报,并与基于类神经网络（ANN）、线性支撑向量机（LSVM）、多元回归（RG）和支持向量机（SVM）4种算法训练的预报模型进行比较。结果表明,由平均气温、最高气温、日照时数3类气象要素构成的40个关键气象因子与小麦始花期早迟密切相关;训练出的6个始花期逐日气象预报模型中,4月10-14日5个模型入选特征变量均为40个,4月15日模型入选特征变量为39个;6个气象预报模型训练集与测试集的平均正确率分别为93.3%和80.4%,平均均方根误差（RMSE）分别为1.860～1.960和2.510～2.709,平均决定系数分别为0.944和0.841;基于RF算法训练的预报模型3项检验指标均优于ANN、LSVM、RG和SVM算法训练的预报模型;利用RF算法模型在2020年和2021年进行预报,提前7～9 d准确预报出当年始花期。由此可见,采用有序等距离抽样拆分出训练集,再基于RF算法构建的皖北地区小麦花期气象预报模型,能够以较高精度对小麦始花期进行预报。 相似文献
7.
大豆食心虫的危害程度(虫食率)受食心虫虫卵的越冬基数、气象条件等定量因素的影响,并受品种、防治情况等定性因素的影响。考虑影响危害程度的11个因素,如上年平均脱荚率、大豆品种、防治情况、越冬幼虫成活率等。利用数量化预测方法所具有的对数据精确性要求不高,同时能考虑定量因子和定性因子的特点,以当年的虫食率为基准变量建立数量化预测模型,对大豆食心虫不同危害程度发生的概率进行预测。在对73个样本三级模型的回报中,完全正确的有63个,回报率为86.30%,预报等级误差为1级的有8个,占总样本数的10.96%,回报精度较好,所建立的模型具有实际意义。 相似文献
8.
橡胶树地上生物量是反映橡胶树生产力、固碳能力和碳储量的重要指标，为提高橡胶树单木地上生物量估测的效率和精度，以橡胶树8年生育种试验林为研究对象，采用无人机LiDAR获取林地点云数据，并实测其地上生物量，基于点云数据提取树高、冠幅、树冠投影面积和树冠体积4个单木结构参数，将此4个参数作为预测因子建立橡胶树单木地上生物量估测模型，比较多元非线性回归和随机森林回归2种模型的估测精度，并分别采用五折交叉验证的方法对2种模型的泛化能力和可靠性进行评估。结果表明：(1)在单木分割的基础上由算法提取的树高和冠幅与直接基于点云人工量测的数值存在很好的一致性，2个参数与实测值的Pearson相关系数分别为0.999和0.951，均方根误差(RMSE)分别为0.109 m和0.452 m;(2)树高、冠幅、树冠投影面积和树冠体积等4个单木结构参数与橡胶树实测单木地上生物量相关性显著，其中树冠体积与地上生物量的Pearson相关系数最高，达0.904,4个参数对橡胶树地上生物量都具有良好的解释性；(3)基于4个单木结构参数建立的2种橡胶树单木地上生物量估测模型均能够取得很好的拟合效果，但是随机森林回归模型的... 相似文献
9.
为探寻小麦赤霉病病穗率预测方法，基于滁州市2005-2020年小麦赤霉病病穗率资料和对应气象资料，运用相关性及灰色关联分析法(GRA)确定小麦赤霉病主要气象影响因子并作为支持向量回归(SVR)模型的输入向量，再利用粒子群算法(PSO)优化SVR模型的惩罚因子C和核函数参数g,建立基于粒子群算法优化的小麦赤霉病预测支持向量回归模型。同时针对本地不同小麦品种，构建PSO-SVR-SOUTH和PSO-SVR-NORTH的PSO-SVR分模型，应用3种模型对滁州地区小麦赤霉病病穗率进行预测。结果表明，拔节期至灌浆期是影响滁州小麦赤霉病的重要时段，各生育时期内降水量、雨日数、湿度、日照等气象因子与赤霉病有高关联；PSO-SVR赤霉病病穗率预测模型的起报时间越接近灌浆期，其预测精度越高，测试样本的预测值与实测值相关系数最高达0.68,均方根误差最小为9.55%;按照不同小麦品种构建的PSO-SVR-SOUTH和PSO-SVR-NORTH模型的预测效果要优于原PSO-SVR模型，其中最迟起报时间的PSO-SVR-SOUTH和PSO-SVR-NORTH模型的平均绝对误差分别较原PSO-SVR模型减少了... 相似文献
10.
春茶适采期预报模型的建立 总被引：4，自引：0，他引：4
根据浙江省临安县和余姚市两地共20年各主要气象资料及与其相应的春茶适采期等调查资料,利用逐步回归分析程序,从45项气象因子中筛选出影响春茶适采期的主要气象因子是:3月下旬有效积温,3月份日照时数,上年10—12月的蒸发量和晴雨指数和4月上旬的有效积温、日照时数及晴雨指数,并建立了适采期预报的主体模型。同时,根据多年多点观察结果,得出茶园海拔、茶树品种、坡向等因子对适釆期预报值的修正值,利用分析过程中得到的一系列中间数据和信息。笔者还对适采期预报模型的研究方法、不同时期影响茶树生育的主要气象因子等问题进行了 相似文献
11.
Sheng-Feng Kuo Feng-Wen Chen Pei-Yu Liao Chen-Wuing Liu 《Paddy and Water Environment》2011,9(4):413-424
The study compares the prediction performances of evapotranspiration by the FAO56 Penman–Monteith method and the pan evaporation
method using the artificial neural network. A backpropagation neural network was adopted to determine the relationship between
meteorological factors and evapotranspiration or evaporation. The evapotranspiration in the ChiaNan irrigated area of Tainan
was considered. Weather data compiled by Irrigation Experiment Station of ChiaNan Irrigation Association were the input layer
variables, including (1) the highest temperature, (2) the lowest temperature, (3) the average temperature, (4) the relative
humidity, (5) the wind speed, (6) hours of sunlight, (7) amount of solar radiation, (8) the dew point, (9) morning ground
temperature and (10) afternoon ground temperature. The importance of the ten weather factors was ranked by the general influence
(GI) factor. Results show that the correlation coefficient between the evapotranspiration in 2004 calculated by FAO56 Penman–Monteith
method and the one predicted by the neural network model with a hidden layer of ten nodes is 0.993. The actual evapotranspiration
is 911.6 cm, and value prediction by the neural network is 896.4 cm, between which two values the error is 1.67%. The results
reveal that the backpropagation neural network based on the FAO56 Penman–Monteith method can accurately predict evapotranspiration.
However, the correlation coefficient between the actual evaporation in 2004 and the value prediction by the neural network
with a hidden layer of ten nodes and an output layer with the pan evaporation as its target output is 0.708. The pan evaporation
is 1,673.1 cm, while the value predicted by the backpropagation neural network is 1,451.7 cm, between which values the error
is 13.23%. The backpropagation neural networks with pan evaporation as target outputs predict the evaporation with large errors.
Moreover, the use of four agricultural weather factors (determined by the GI) including wind speed, average temperature, dew
point and maximum temperature as input variables, and a hidden layer of three nodes in the backpropagation neural network
model can successfully predict evapotranspiration based on the FAO56 Penman–Monteith method (R = 0.98, error = 1.35%). 相似文献
12.
Fresh ryegrass and lucerne were macerated and compressed into thin mats over a 4-week period at two yield levels. The mats were left lo dry outside during the day. and inside overnight, and compared with unconditioned crops. Under a low swath yield of 4 t DM ha−1 , mats required 0·7-1·4 mm pan evaporation lo reach 70% moisture, suitable for wilted silage, compared with 1·8-3·8 mm pan evaporation for unconditioned crops. On an average non-rainy day. mats were ready to harvest as wilted silage after 2–5 h, whereas the unconditioned crop required between 6 h and 36 h of wilting. With a high swath yield of 8 t DM ha−1 , mats required 1·4-3·0 mm pan evaporation to reach 70% moisture compared with 2·4-5·1 mm for unconditioned windrows. Low-yield mats reached 20% moisture, suitable for hay, in 2 d of drying, after 4·5-5·3 mm of pan evaporation. The thickness and cohesion of the mats were measured to assess their sensitivity to mechanical handling. The effect of controlled rainfall on mats was also investigated. Since mat making was most effective in low-yield crops, it could become a useful complement to low-input, extensive forage production. Mat making could eliminate most silage effluent losses; it could re introduce haymaking of ryegrass as a viable system under certain circumstances. 相似文献
13.
《Field Crops Research》1995,41(3):179-188
Maize and bean were grown under varying levels of nitrogen fertilizer, plant population, and irrigation at Kiboko, Kenya in the short rains 1990, 1991, 1992 and the long rains 1991. The production of dry matter was not affected significantly by any treatment, because treatments only had a small impact on the balance between evaporation and transpiration. In all seasons the greatest loss of water from the profile was through direct evaporation from the soil surface. Transpiration was always less than 25% of rainfall. The ratio of transpiration (T) to evapotranspiration (E + T) was small (0.23), but increased from 0.15 to 0.40 as rainfall increased from 158 mm in the long rains 1991 to 470 mm in the short rains 1992. Treatments had little impact on the balance between transpiration and evaporation from the soil surface. The average transpiration efficiencies for maize and bean were 89 and 29 kg shoot dry matter ha−1 mm−1, respectively. For each crop there was a 60% change in transpiration efficiency between the short and the long rain season which could be accounted for by differences in saturation vapour pressure deficit. 相似文献
14.
夏玉米耗水规律及水分胁迫对其生长发育和产量的影响 总被引：24，自引：10，他引：14
依据灌溉试验资料,研究夏玉米生育期内的耗水规律及植株蒸腾与棵间蒸发变化规律,分析水分胁迫对其生长发育和产量形成的影响。结果表明,水分适宜处理的夏玉米,生育期耗水量425.25mm,各时段耗水量占全生育期耗水量的百分比分别为14.34%、10.49%、10.43%、15.70%、27.16%、13.63%和8.25%,相应的日平均耗水强度分别为4.064、2.973、2.958、4.452、7.699、3.860和2.192mm/d;玉米田的棵间蒸发量较大,约占其整个生育期总耗水量的35%～38%;各生育时段遭受水分胁迫均会引起一系列不良后果,其中尤以抽雄吐丝前后40d左右缺水影响最大,其次是拔节期缺水。 相似文献
15.
Quantification of soil surface evaporation under micro-scale advection in drip-irrigated fields 总被引：1，自引：0，他引：1
Kozue Yuge Tomokazu Haraguchi Yoshisuke Nakano Masaharu Kuroda Mitsumasa Anan 《Paddy and Water Environment》2005,3(1):5-12
The objective of this study is to quantify soil surface evaporation under micro-scale advection in drip-irrigated fields. A numerical model for estimating soil surface evaporation under micro-scale advection, assuming drip-irrigated fields, is introduced. Results indicate that the soil surface evaporation changes spatially. Soil surface evaporation at the upwind edge of wet soil portions adjacent to dry soil portions increased abruptly. On the other hand, soil surface evaporation at the upwind edge of dry soil portions adjacent to wet soil portions decreased, and condensation was observed. These phenomena were considered to be due to airflows between differing climates. To verify the accuracy of the model, an experiment using a wind tunnel was conducted. The simulated soil surface evaporation results from the model were consistent with the experimental data. The numerical model introduced here is an effective way to quantify soil surface evaporation under micro-advective conditions. 相似文献
16.
Quantification of the effects of adjuvants on droplet behaviour on plant surfaces is needed to improve pesticide spray application efficiency for soybeans. Dispersion and evaporation of single 300-μm diameter droplets amended with each of four spray adjuvants at five concentrations were investigated for four soybean plant surfaces (abaxial and adaxial leaflet surfaces, petiole, basal stem). The four adjuvants were a crop oil concentrate (COC), a modified seed oil (MSO), a non-ionic surfactant (NIS) and an oil surfactant blend (OSB). A single-droplet generator was used to produce and deposit 300-μm diameter droplets on target surfaces under controlled environmental conditions. Adjuvants significantly increased the dispersion (or wetted area) of droplets on plant surfaces. Droplet-wetted areas increased with increased adjuvant concentrations but not in direct proportion. The average increases of wetted areas across the four soybean plant surfaces were 443, 462, 416, or 343% when the spray mixture was amended with COC, MSO, NIS or OSB at the manufacturer-recommended concentrations, respectively. Among the four surfaces, the largest wetted area was on the abaxial surface, followed by the adaxial surface, the petiole and then the basal stem. Droplet evaporation times were inversely proportional to the wetted areas. The evaporation time of 300-μm diameter droplets ranged from 36 to 142 s on the four surfaces when the spray mixture was amended with an adjuvant, whereas the water-only droplets ranged from 161 to 190 s. The results demonstrated that use of adjuvants offers great potential to improve the homogeneity of sprayed pesticides, to increase spray coverage and to reduce pesticide application rates on soybean plants. These effects could benefit farmers economically and reduce environmental contamination by pesticides. 相似文献
17.
The drying pattern of grass swaths was monitored using microclimate techniques during a 48 h summer wilting period of good drying conditions. Swath drying pattem, which is dependent upon the swath energy relations, water relations and resistances to evaporation, was explained in terms of changes in the balance of available energy, ambient vapour pressure deficit and swath internal resistance to water vapour transfer throughout the drying period. A typical drying pattern showed limited swath evaporation between sunrise and 09.00 hours, and rapid evaporation between 09.00 hours and 12.00 hours when available energy and vapour pressure deficit were high and swath resistance to water loss low. Between 12.00 and 18.00 hours, because of a decrease in available energy and increase in swath resistance, swath evaporation was reduced. Between 18.00 hours and sunset swath evaporation was near zero. 相似文献
18.
For sustainable development of irrigated agriculture in arid regions, improvement of water use efficiency is essentially required to maintain current production levels and meet food and fiber for population growth in future. To achieve high water use efficiency, a key consideration is to reduce unnecessary soil water loss due to evaporation. In this article, regional daily evaporation over Hetao Irrigation District in a typical arid region during the irrigation period of 2009 was determined by a developed maximum surface temperature model combining Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery. The results showed that maximum land surface temperature (LST) from MODIS satellite imagery was relatively higher in the western and middle parts than that of the eastern part of the district. At the same time, the mean minimum LST was shown somewhat higher in the eastern part. Mean daily evaporation was relatively higher in the eastern part, which showed water consuming is higher in the eastern part of the district. During the irrigation period of 2009, the total income water (irrigation water and rainfall) amount is 590.3 mm, and the outcome water (drainage discharge and evaporation) amount is 497.5 mm. The surplus of 92.8 mm in the irrigated season is considered to be consumed in winter season. Throughout the irrigated season, income and outcome almost equals each other. The daily evaporation distribution map could specify particular water consuming areas over the district where high daily evaporation may be occurred. 相似文献
19.
Hassanpanah D Gurbanov E Gadimov A Shahriari R 《Pakistan journal of biological sciences: PJBS》2008,11(10):1354-1359
This experiment was done on the three potato cultivars [Agria (susceptible), Satina (semi-tolerant) and Ceaser (tolerant to water deficit)] and three irrigation treatments (after 30 mm evaporation from basin class A, after 60 mm evaporation + spraying by Potassium Humate, and after 60 mm evaporation from basin class A) for two locations in 2007. Experimental design was Split Plot with three replications. Potassium Humate spraying (250 mL ha(-1)) were done in three stages of emergence, before tuberization and during tuberization period. Combined analysis of variance showed that there were significant differences between locations, cultivars, irrigation treatments and location x cultivars interaction as effect on tuber yield. Comparison of means for irrigation treatments showed that spraying by Potassium Humate in stress condition induced increasing of tuber yield. Spraying by Potassium Humate in water deficit condition increased tuber yield up to 11.01 ton ha(-1). Ceaser had the highest tuber yield. It had higher tolerance to water deficit as well. Ceaser had a high potential in control and severe stress. Decrease in yield of Ceaser after 60 mm evaporation + spraying by Potassium Humate and after 60 mm evaporation from basin class A, relative to control (after 30 mm evaporation from basin class A) was 1.03 and 13.08 ton ha(-1) but for Satina was 7.83 and 16.61 ton ha(-1), respectively. Satina had the lowest Environmental Variance, Environmental Variance Coefficient, Finlay and Wilkinson's and Eberhart and Russell's model and was the most stable cultivar. Lin and Binns parameter showed that Ceaser and Satina were the most stable cultivars. Results of GMP, STI and MSTI were very considerable and Ceaser and Satina had a high yield in water stress and control conditions. 相似文献
20.
玉米灌溉田土壤水分变化及其耗水规律研究 总被引：4，自引：1，他引：3
以辽宁省主要旱地作物玉米为研究对象,研究了其灌溉田土壤水分变化及其耗水规律。在试验条件下,0～20 cm土层水分含量最低,整个玉米生育期内水分变化幅度最大;30～50 cm土层由于受长期耕作习惯等因素的影响土壤的黏滞度较高,保持较明显的水分梯度,并使50～90 cm土层水分变化与0～20 cm土层相比滞后1～3 d;90～120 cm土层土壤水分受根系影响较小,变化不大。玉米生育前期农田实际蒸散量和参考蒸散量均趋于不断增大,生育中期个别时段内由于受阴雨气候影响蒸散量有所减弱;参考蒸散量最大值出现在玉米播种后第46天左右,农田实际蒸散量最大值出现在玉米出苗后第96天左右,玉米生育后期两者逐渐减弱。玉米生育前期表层土壤棵间蒸发量占实际蒸散量的比重较大,生育中期棵间蒸发量受降雨和灌溉等因素影响,变化幅度较大,生育后期相对较小。随着玉米叶面积增加,作物系数不断增加,在播种后第81天左右作物系数达最大值,之后作物系数逐渐下降。 相似文献