Milk Yield of Holstein Cows Induced into Lactation Twice Consecutively and Lactation Curve Models Fitted to Artiifcial Lactations

Nineteen multiparous barren Holstein cows were subjected to an induction of lactation protocol for 21 d administering estradiol cypionate （2 mg kg-1 of body weight （BW） d-1, on day 1 to 14）, progesterone （0.10 mg kg-1 of BW, on day 1 to 7）, lfumethasone （0.03 mg kg-1 of BW, on day 18 to 20） and recombinant bovine somatotropin （rbST;500 mg per cow, on day 1, 6, 16 and 21）. At the end of lactation and with a minimum of a 2-mon dry period, the same cows were again hormonally induced into lactation. Cows in both lactations were not artiifcially inseminated, they were milked 3 times daily and received rbST throughout lactation. Mean accumulated milk yield at 305 d in milk （DIM） did not differ between the ifrst and second induced lactations （（9 710 ＆#177;1 728） vs. （9 309＆#177;2 150） kg;mean＆#177;SD）. Total milk yield （（12 707＆#177;3 406） vs. （12 306＆#177;4 218） kg;mean＆#177;SD） and lactation length （（405＆#177;100） vs. （410＆#177;91） d;mean＆#177;SD） were not different between the ifrst and second induced lactations. In a second study, 15 empirical models including exponential, power law, yield-density, sigmoidal and miscellaneous models were compared for their suitability by modeling 12-mon （n=334）, 18-mon （n=164） and 29-mon （n=22） lactation cycles of Holsteins cows induced into lactation and treated with rbST throughout the lactation. Hoerl （Y=ab1/xxc）, Wood （Y=axb exp（cx）） and Dhanoa （Y=ax（bc）exp（cx）） models were equally suitable to describe 12-mon lactations. An exponential model with ifve parameters （Y=exp（a＋bx＋cd2＋e/x）） showed the best ift for milk yield for 18-mon lactations. The rational model （Y=a＋bx/1＋cx＋dx2） was found to produce the closest ift for 29-mon lactations. It was concluded that, with the protocol used in the present study, multiparous cows respond favorably to a second cycle of induced lactation, with milk yield similar to that experienced during the ifrst cycle. Thus, dairy producers might be able to lengthen the productive life of infertile high producing cows with a renewal of artiifcial lactation, which would imply an overall reduction in voluntary culling of cows. Also, various equations used to describe the lactation curves demonstrated the potential for iftting monthly milk records of Holstein cows with prolonged lactations and induced hormonally into lactation.     

Effects of Phosphorus Application in Different Soil Layers on Root Growth,Yield, and Water-Use Efficiency of Winter Wheat Grown Under Semi-Arid Conditions

Deep phosphorus application can be a usefull measure to improve crops＇ performance in semi-arid regions, but more knowledge of both its general effects and effects on specific crops is required to optimize treatments. Thus, the aims of this study were to evaluate the effects of phosphorus（P） application at different soil layers on root growth, grain yield, and water-use efficiency（WUE） of winter wheat grown on the semi-arid Loess Plateau of China and to explore the relationship between root distribution and grain yield. The experiment consisted of four P treatments in a randomized complete block design with three replicates and two cultivars： one drought-sensitive（Xiaoyan 22, XY22） and one drought-tolerant（Changhan 58, CH58）. The four P treatments were no P（control, CK）, surface P（SP）, deep P（DP）, and deep-band P application（DBP）. CH58 produced larger and deeper root systems, and had higher grain yields and WUE, under the deep P treatments（DP and DBP） than under SP, clearly showing that deep P placement had beneficial effects on the drought-tolerant cultivar. In contrast, the grain yield and root growth of XY22 did not differ between DP or DBP and SP treatments. Further, root dry weight（RW） and root length（RL） in deep soil layer（30-100 cm） were closely positively correlated with grain yield and WUE of CH58（but not XY22）, highlighting the connections between a well-developed subsoil root system and both high grain yield and WUE for the drought-tolerant cultivar. WUE correlated strongly with grain yield for both cultivars（r=0.94, P〈0.001）. In conclusion, deep application of P fertilizer is a practical and feasible means of increasing grain yield and WUE of rainfed winter wheat in semi-arid regions, by promoting deep root development of drought-tolerant cultivars.     

The Effects of Climate Change on the Planting Boundary and Potential Yield for Different Rice Cropping Systems in Southern China

Based on climate data from 254 meteorological stations, this study estimated the effects of climate change on rice planting boundaries and potential yields in the southern China during 1951-2010. The results indicated a signiifcant northward shift and westward expansion of northern boundaries for rice planting in the southern China. Compared with the period of 1951-1980, the average temperature during rice growing season in the period of 1981-2010 increased by 0.4＆#176;C, and the northern planting boundaries for single rice cropping system （SRCS）, early triple cropping rice system （ETCRS）, medium triple cropping rice system （MTCRS）, and late triple cropping rice system （LTCRS） moved northward by 10, 30, 52 and 66 km, respectively. In addition, compared with the period of 1951-1980, the suitable planting area for SRCS was reduced by 11%during the period of 1981-2010. However, the suitable planting areas for other rice cropping systems increased, with the increasing amplitude of 3, 8, and 10%for ETCRS, MTCRS and LTCRS, respectively. In general, the light and temperature potential productivity of rice decreased by 2.5%. Without considering the change of rice cultivars, the northern planting boundaries for different rice cropping systems showed a northward shift tendency. Climate change resulted in decrease of per unit area yield for SRCS and the annual average yields of ETCRS and LTCRS. Nevertheless, the overall rice production in the entire research area showed a decreasing trend even with the increasing trend of annual average yield for MTCRS.     

Effects of Powdery Mildew on 1000-Kernel Weight,Crude Protein Content and Yield of Winter Wheat in Three Consecutive Growing Seasons

In order to clarify the impact posed by wheat powdery mildew （Blumeria graminis f. sp. tritici） on the yield and yield components in different epidemic seasons, field trials were conducted in three growing seasons, 2009-2010, 2010-2011 and 2011-2012, in Langfang City, Hebei Province, China. The relationships between 1000-kernel weight, crude protein content of grain and yield and disease index （DI）, as well as area under disease progress curve （AUDPC） were studied. The models of the percentage of loss of 1000-kernel weight, crude protein content and yield were constructed using DI at critical point （CP） of growth stages （GS） and AUDPC in the three growing seasons, respectively. The CPs for estimating 1 000-kernel weight, crude protein content of grain and yield of wheat caused by powdery mildew were GS 11.1, GS 10.5.3 and GS l 0.5.3, respectively. Models based on DI at CP to estimate the percentage of loss of 1000-kernel weight, crude protein content of grain and yield were better than models based on AUDPC. And models of the percentage of loss of 1000-kernel weight, crude protein content and yield for 2011-2012 season were significant different from these for 2009-2010 and 2010-2011 seasons. These results indicated that besides powdery mildew, weather conditions also had influence on 1 000-kernel weight, crude protein content of grain and yield loss of wheat when powdery mildew occurred.     

线性回归与BP神经网络方法的山东粮食产量预测比较研究

山东省是我国传统农业大省,粮食产量对我国粮食总产量的影响较大,因此对山东省粮食产量进行预测具有重大意义.分别利用多元线性回归方法和BP神经网络两种预测方法对山东粮食产量进行预测,并对两种方法的预测结果进行分析比较,实验证明,BP神经网络平均预测精度高于多元线性回归模型,且各期预测精度较多元线性回归模型更稳定,但随时间推移,误差增大,因此BP神经网络预测模型较适用于近期粮食产量预测.     

冀玉13号高产优质制种技术研究

通过对冀玉13号玉米亲本农艺性状的详细调查、父母本错期试验、母本密度试验等研究,集成该品种高产、优质制种技术。     

黄河三角洲地区田菁种植密度对其生长发育及籽粒产量的影响

[目的]为了研究不同品种和密度对田菁籽粒产量及其相关性状的影响。[方法]比较田菁在不同密度下植株的株高、茎粗、地上部鲜重、结荚数、结荚枝数、秕粒率等指标。[结果]各密度下同一品种田菁生长性状、结荚特征具有明显差异,籽粒产量虽变化不大,但以7.5万株/hm2密度下秕粒率最低,籽粒更饱满;不同田菁品种间籽粒产量差异较大。[结论]通过选育品种、合理调节田菁种植密度等措施,可获得品质更高的田菁籽粒,并实现高产,为黄三角地区田菁胶的工业化生产提供丰富的原料。     

安徽蚌埠“06.01”暴雨预报因子程序式预报

利用常规气象观测资料和简明暴雨预报因子程序,对2014年6月1日出现在安徽蚌埠市的暴雨过程进行诊断分析,中低层切变线、暖湿气流强烈辐合、充足的不稳定能量释放是形成暴雨元素,并用暴雨预报程序进行预报。     

基于ARMA模型的运城市果蔬肉类价格预测研究

[目的]预测果蔬肉类价格。[方法]采用自回归滑动平均模型(ARMA模型)对价格进行预测。[结果]近6周的预测结果可信度高,具有较低的相对误差率。[结论]运用ARMA模型可对果蔬肉类价格进行预测且预测效果良好。     

地力水平和种植密度对冬小麦子粒产量和氮素利用率的影响

[目的]旨在探讨不同地力水平下冬小麦子粒产量和氮素利用率对种植密度的响应并分析子粒产量和氮素利用率协同提高的途径,为制定冬小麦高产高效栽培管理措施奠定理论基础。[方法]试验在高、低两个地力条件下进行,以大穗型冬小麦品种泰农18为试验材料,设置135万、270万和405万株/hm23个种植密度,研究地力水平和种植密度对子粒产量及构成、氮素吸收效率、氮素利用效率和氮素利用率等相关指标的影响。[结果]高地力水平下子粒产量高于低地力水平,但氮素利用效率和氮素利用率均较低。各地力水平下,提高种植密度可显著提高冬小麦穗数和子粒产量,提高成熟期地上部氮素积累量和氮素吸收效率,但氮素收获指数和氮素利用效率随种植密度上升呈下降趋势,增密对子粒含氮量无显著影响。各地力水平下增密后氮素吸收效率增加的幅度远高于氮素利用效率降低的幅度,所以氮素利用率随着种植密度的提高而呈上升趋势。低地力水平下增密后子粒产量和氮素利用率提高的幅度均高于高地力地块。[结论]在高、低地力水平下,增加种植密度均可提高子粒产量和氮素利用率,有利于实现冬小麦的高产高效栽培,且低地力水平下增密后子粒产量和氮素利用率的增幅高于高地力水平。