12个紫花苜蓿引进品种的产量及持久性评价

通过3年田间试验,对12个紫花苜蓿引进品种的产量及持久性进行了评价.结果表明:紫花苜蓿在当地的持久性较差,但其产量高于当地当家豆科牧草白三叶在相同年份的产量,紫花苜蓿在当地具有一定种植潜力;游客、威可、四季绿这3个品种的持久性较好且产量也较高;海盗和超级7生产性能高而持久性较差;盛世、特瑞和山锐持久性较好,但生产性能一般或较低.     

玉米生长量、养分吸收量和及氮肥利用率的动态变化

在不同水、氮供应条件下，研究了玉米干物质累积、养分吸收及氮肥利用率的变化动态。结果表明，植株干物质和养分吸收量，随生育期延长而持续增加，变化动态可用S曲线方程拟合。对干物质和养分累积方程求导，得到了干物质累积和养分吸收速率。玉米生长期间干物质累积速率前期上升快，至高峰后缓慢下降。在氮、磷、钾三要素中，氮、钾吸收速率高，上升快，下降也快；磷吸收速率低，上升慢，下降亦慢。养分最大吸收速率出现的时间，钾最早，氮次之，磷最晚，但均早于干物质最大累积速率出现时间。氮肥利用率与干物质累积、养分吸收速率有类似变化趋势；氮肥最高瞬时利用率与氮素最大吸收速率出现的时间基本一致。灌水明显提高了氮肥累积利用率和瞬时利用率；水分和氮素供应虽然增加了养分吸收速率和干物质累积速率，但未改变其变化趋势。     

抽穗至成熟期气温对弱春性小麦千粒重和不孕小穗率的影响

弱春性小麦品种的千粒重和不孕小穗率呈极显著的负相关.抽穗至成熟期间的适温范围是21～26℃.千粒重与抽穗至成熟天数呈极显著的正相关.在抽穗至成熟期间,千粒重与平均日均温呈负相关,与平均日最高温度呈极显著的负相关,而与平均昼夜温差呈极显著的正相关.     

不同育秧方式水稻恶苗病发生规律研究

种子带菌量的高低和催芽时间的长短 ,对水稻恶苗病发生的轻重具有重要的影响。在不同的育秧方式条件下 ,水稻恶苗病的侵染具有不同过程     

水稻边际优势利用栽培增产的生态原因研究

对大小垄栽培群体和30cm等行距栽培群体不同层次的光照强度、群体行间温、湿度等生态因子及每穴穗数、每穗实粒数和单穴生产力三个产量性状和不同分蘖时期每穴茎数的边际效应指数进行了研究。结果表明,大小垄栽培群体下部的光照强度和透光率显著增加,行间温、湿度降低,使群体内部的光、温条件得到改善。每穴穗数、每穗实粒数和单穴生产力及不同分蘖时期每穴茎数的边际效应指数降低,说明实行大小垄种植后,群体内部的长势与边行的差距缩小,群体内部个体的生长优势得到发挥,达到了利用边际优势增产的目的。     

氮肥水平和种植密度对冬小麦茎秆抗倒性能的影响

以中穗型小麦品种山农15为材料,在2个氮肥水平(180 kg hm^-2和240 kg hm^-2)和2个密度(150×10⁴ hm^-2和225×10⁴ hm^-2)下,研究了抗倒性能相关的形态学特征、茎基部节间化学组分、抗倒指数（茎秆机械强度/茎秆重心高度）、木质素合成相关酶活性和籽粒产量的变化特点,以及抗倒指数与形态学和生化指标的相关性。结果表明,施氮水平和种植密度间存在显著的互作效应,当施氮水平由180 kg hm^-2增至240 kg hm^-2或种植密度由150×10⁴ hm^-2增加到225×10⁴ hm^-2时,茎秆重心高度、基部节间长度显著提高,基部节间直径、厚度、充实度、机械强度和抗倒指数显著降低,同时茎秆基部节间纤维素含量、木质素含量显著减少,含氮量显著升高,碳氮比(C/N比)以及木质素合成相关酶活性显著降低。逐步回归分析表明,氮肥水平对小麦抗倒性的影响大于种植密度。本试验条件下,氮肥水平180 kg hm^-2和种植密度为150×10⁴ hm^-2的处理穗数较低,但穗粒数和千粒重显著高于其它处理,因而籽粒产量最高。建议在降低氮肥用量至180 kg hm^-2的同时降低种植密度至150×10⁴ hm^-2,可在增强植株抗倒伏能力的同时获得高产。     

烤烟烟片吸料速率及影响因素研究

[目的]为卷烟加料和配叶贮叶工序加工工艺的选择与条件设定提供依据。[方法]采用浸泡法测定烟片吸料速率,并考察烟片微观结构、含水率和料液温度等对烟片吸料速率的影响。[结果]烤烟烟片吸收料液过程符合二级动力学方程;烤烟烟片截面孔数量为叶面的17～76倍,孔率为叶面的33～183倍,将烟片制成叶丝后,料液吸收速率提高2.2～3.1倍;随着含水率增大,烟片吸料速率降低;随着料液温度升高,烟片吸料速率增大。[结论]将烤烟烟片制成叶丝、提高料液温度、降低烟片含水率,均可提高烟片吸料速率。     

不同区段和药剂处理对山药种薯出苗率的影响

试验结果表明:以不同区段的山药作为种薯进行栽培,选择栽子的效果较好,出苗率高达54.99%,较随机区段和山药尾子差异极显著;用50%多菌灵处理苗床育苗移栽大田效果显著,其出苗率达到91.76%,与其他处理的出苗率差异显著。     

Effect of seed treatment for laboratory germination of Albizia chinensis

Seeds of Albizia chinensis(Osb.) Merr. in addition to water were also treated with different treatments by incubating in ethyl alcohol, acetone, and petroleum ether at room temperature for different du...     

One or Two Feeders for Groups of 16 Growing–Finishing Pigs: Effects on Health and Production

Over a 3-year period, seven batches of growing-finishing pigs in groups of 16 pigs (total 672 pigs) were fed using one or two singlespace feeders. The pigs with access to two feeders had a significantly lower number of skin lesions (P<0.0001) and higher daily weight gain than did the pigs with access to one feeder (863 vs. 837 g day- 1 , P<0.05). The within-pen variation in daily weight gain was higher in the pens with one feeder than in the pens with two feeders (SD 139 vs. 106g day- 1 , P<0.0001). The pigs with access to two feeders consumed more feed during the period when they were allowed to eat ad libitum , in comparison to the pigs with access to one feeder (2.07 vs. 1.97 kg day- 1 , P<0.05). The feed conversion ratio of the pigs did not differ between the two treatments. No differences in carcass meat percentage, health or number of remarks at slaughter were detected. A comparison was made between using computerized IVOG® feeders, with individual recording of feed intake, and conventional feeders. The feed conversion ratio was poorer for the pigs fed with the IVOG-feeders than for those fed with conventional feeders. The automatic recordings from the IVOG-system showed that there had been a higher daily feed intake during the ad libitum period. During the restricted period the pigs had a lower daily weight gain than with the conventional feeders.