反刍动物瘤胃酸中毒发病机理的研究——山羊过食玉米后酸碱血气参数值的分析

12头杂交山羊,分别投饲玉米粉100、80和60g/kg体重,在发病前后测定血液pH值和血气参数值。研究结果表明,山羊玉米粉的致死量为100g/kg体重,80～60g/kg体重可引起山羊严重代谢性酸中毒。100g/kg体重组变化比其它各组明显(P<0.01),在瘤胃酸中毒过程中,静脉血pH值明显降低(P<0.01),静脉血Pco_2、Tco_2下降(P<0.05),BB、BE、BEec、HCO_3~-、PO_2、O_2CT和O_2ST降低(P<0.01),各组变化相一致,仅在酸中毒程度上存在差异,血pH位和血气参数值的测定对制定反刍动物瘤胃酸中毒的治疗措施有重要意义。     

太空飞行对玉米种子的生物学效应

本试验对５００多粒太空飞行后回收的玉米种子的生长发育进行了观察。种子置于一个长期辐射照装置（ＩＤＥＦ）内，在低地球轨道飞行了６９月。结果表明，太空环境对玉米种子发芽率无影响。当代植株中发现矮化，株色和叶鞘色变化，叶片出现黄或白色条纹等形态变异。以叶片黄，白条纹出现率为变异率的指标，与加速重离子束对同一玉米品种辐照获得的数据相对比，可估算出种子在太空飞行期间受到辐射的平均剂量相当于６３５ｃＧｙ的γ射     

我国玉米骨干自交系形态性状的鉴定与评价

通过对我国玉米54份骨干自交系的植株性状、产量性状及生育期性状的分析评价,筛选出了各单个性状表现优良与较差的自交系,分析了四大杂优类群间在形态性状方面的差异,为我国玉米种质的改良与创新提供了依据。     

北方早熟玉米9个主要性状间的灰色关联度分析

本文运用灰色关联度分析方法,对15个玉米杂交种(或组合)的9个主要性状(单株粒重、子粒率、叶片数、百粒重、子粒类型、蛋白质含量、脂肪含量、淀粉含量、赖氨酸含量)间的相互关系进行了研究分析,为优质高产玉米杂交种的选育提供参考.     

紫色玉米穗轴色素的提取及其稳定性研究

对紫色玉米穗轴色素的提取及其稳定性进行了分析研究。结果表明,玉米穗轴色素提取简便,提取率为10.85%;色素的耐光、耐热性较好;耐氧化性、还原性较差;葡萄糖、蔗糖、氯化钠及金属离子对色素稳定性有一定的促进作用。     

东北部分春玉米地乙莠合剂防效下降的原因和对策

在我国的东北春玉米区,长时间使用乙草胺和莠去津,导致部分地区防效下降。在吉林省农安县通过定点试验、大面积试验和大范围调查发现,乙莠合剂防效下降的主要原因是因为杂草群落结构的变化引起的,同时降水的减少和药剂使用方法不当也起了一定的作用,未发现产生明显抗性的迹象。在未来,乙莠合剂仍是该地区玉米地除草剂的主要药剂,对于杂草群落尚未发生变化的地块仍然有很好的防效,而在杂草群落发生变化的地区,应适当更换除草剂或适当增加轮作;针对当地特点,适当推迟乙莠合剂的喷施时间,采用机械喷雾、加大用水量等措施来提高乙莠合剂的防效。     

麦田套种紧凑型玉米应掌握的五项关键技术

本文根据1993～1994年的小区试验和潍坊市麦套紧凑型夏玉米大面积单产8250～1125kg/hm²的高产实践，总结出了麦田套种紧凑型夏玉米应掌握的五项关键技术．即合理增株，扩大群体；苗期早管，促进幼苗均衡生长；增加肥料投入，合理运用肥水；防虫治虫，为玉米创造良好的生育环境；适当晚收，提高单位面积产量等。试验与生产实践表明，运用上述五项关键技术措施，可使紧凑型夏玉米增产25.38%～32.57%。     

The specific dynamic action of southern catfish, <Emphasis Type="Italic">Silurus meridonalis</Emphasis> Chen,fed diets containing either raw or precooked corn starch or glucose

The growth performance of carnivorous southern catfish (Silurus meridionalis) was lower when fed a diet containing glucose as a carbohydrate source than when fed one containing starch. To test whether this decreased growth performance was partly due to higher metabolic costs induced by the fast assimilation of dietary glucose, the postprandial metabolic responses of southern catfish juvenile (36.7 ± 1.9 g) fed diets containing either raw or pre-cooked corn starch and glucose were investigated at 27.5°C. The peak metabolic rate of fish fed a raw corn starch diet was significantly higher than that of fish fed precooked corn starch and glucose diets (P < 0.05). The specific dynamic action (SDA) coefficients (energy expended on SDA as a percentage of energy content of the meal) of fish fed raw or precooked corn starch diets were significantly higher than that of fish fed a glucose diet (P < 0.05). The postprandial metabolic rate of fish fed a raw starch diet displayed a classic response – increased metabolic rate immediately after feeding, followed by a decreased metabolic rate several hours after feeding – as has been documented earlier in this species. However, the postprandial metabolic rate of fish fed a glucose diet had two alternating cycles of increasing and decreasing metabolic rate, which has not been reported previously. This bimodal pattern of the SDA curve was also found in a subsequent experiment in which purified d-glucose (0.1 g dry mass) was packed into sections of grass carp (Ctenopharyngodon idellus) intestine (0.05 g dry mass). The results suggest that the digestibility and absorption speed of the dietary carbohydrate has a significant effect on postprandial metabolic response in juvenile southern catfish. The results of this study may provide useful data in terms of the utilization of dietary carbohydrates by carnivorous fishes.     

松杉树皮和玉米秸秆堆肥对番茄根结线虫病的防治及土壤微生物的影响

日光温室栽培条件下,通过盆栽试验研究了松杉树皮、玉米秸秆堆肥对番茄的生长、产量、根结线虫发病情况及土壤微生物的影响。结果表明,松杉树皮、玉米秸秆堆肥对番茄根结线虫病具有一定的防治效果,以松杉树皮、玉米秸秆堆肥混施效果最好,同时各种堆肥的施用均增加了番茄的生物量及土壤微生物数量。通过相关性分析得知,根结线虫与土壤微生物数量存在显著负相关,说明土壤微生物群落的多样性对根结线虫病的发生产生了抑制作用。     

Simulating water content, crop yield and nitrate-N loss under free and controlled tile drainage with subsurface irrigation using the DSSAT model

In southwestern Ontario, rain-fed crop production frequently fails to achieve its yield potential because of growing-season droughts and/or uneven rainfall distribution. The objective of this study was to determine if the Decision Support System for Agrotechnology Transfer (DSSAT) v4.5 model could adequately simulate corn and soybean yields, near-surface soil water contents, and cumulative nitrate-N losses associated with regular free tile drainage (TD) and controlled tile drainage with optional subsurface irrigation (CDS). The simulations were compared to observations collected between 2000 and 2004 from both TD and CDS field experiments on a Perth clay loam soil at the Essex Region Conservation Authority demonstration farm, Holiday Beach, Ontario, Canada. There was good model-data agreement for crop yields, near-surface (0-30 cm) soil water content and cumulative annual tile nitrate-N loss in both the calibration and validation years. For both TD and CDS, the CENTURY soil C/N model in DSSAT simulated water content and cumulative tile nitrate-N loss with normalized root mean square error (n-RMSE) values ranging from 9.9 to 14.8% and 17.8 to 25.2%, respectively. The CERES-Maize and CROPGRO-Soybean crop system models in the DSSAT simulated corn and soybean yields with n-RMSE values ranging from 4.3 to 14.0%. It was concluded that the DSSAT v4.5 model can be a useful tool for simulating near-surface soil water content, cumulative tile nitrate-N losses, and corn and soybean yields associated with CDS and TD water management systems.