几种添加物对蛋清蛋白热诱导不可逆凝胶性质的影响

以蛋清蛋白为原料,制备热诱导制取不可逆性凝胶,在单因素试验基础上,采用三因素二次正交旋转组合设计研究了三聚磷酸钠(X1)、瓜尔胶(X2)、酪蛋白酸钠(X3)对蛋清蛋白热诱导不可逆性凝胶性质的影响,建立了二次回归模型。结果表明,X12,X22在0.01水平上差异极显著,X32在0.05水平上差异显著;最佳配比为三聚磷酸钠质量分数0.100%,瓜尔胶质量分数0.100%,酪蛋白酸钠质量分数0.250%,此时蛋清蛋白凝胶强度预测值为550 g/cm2,实际值为542 g/cm2,二次正交旋转组合设计法可信度强,具有很好的预测意义。     

Impact of different crop rotations and tillage systems on weed infestation and productivity of bread wheat

Crop rotation and tillage systems have important implications for weed infestation and crop productivity. In this study, five tillage systems viz. zero tillage (ZT), conventional tillage (CT), deep tillage (DT), bed sowing (60/30 cm with four rows; BS₁) and bed sowing (90/45 cm with six rows; BS₂) were evaluated in five different crop rotations viz. fallow-wheat (FW), rice-wheat (RW), cotton-wheat (CW), mungbean-wheat (MW) and sorghum-wheat (SW) for their effect on weed infestation and productivity of bread wheat. Interaction between different tillage practices and cropping systems had significant effect on density and dry biomass of total, broadleaved and grass weeds, agronomic and yield-related traits, and grain yield of bread wheat. The un-disturbed soils (ZT) under fallow-wheat or mungbean-wheat rotations favoured the weed prevalence (a total weed dry biomass of 72.4–109.6 and 105.6–112.1 g m⁻² in first and second year, respectively). Contrary to this, the disturbed soils (CT, DT, BS₁ and BS₂) had less weed infestation with either of the rotations (a total weed biomass of 0.4–7.1 and 1.1–5.4 g m⁻² in first and second year, respectively). Sorghum-wheat rotation had strong suppressive effect on weed infestation in all tillage systems. The impact of crop rotation was more visible during second year of experimentation. Bed sown wheat (BS₁ and BS₂) in mungbean-wheat rotation had the highest wheat grain yield (6.30–6.47 t ha⁻¹) compared to other tillage systems in different crop rotation combinations.     

灌溉方式对大豆光合性状及土壤水分利用率的影响

设置均匀灌溉、固定隔沟灌溉、交替隔沟灌溉3种灌溉方式,分别在大豆开花期、结荚期和鼓粒期进行灌溉,每次单沟灌水量分为60、45和30 mm 3个水平,以不灌溉为对照,研究了灌溉方式对大豆光合特性的影响.结果表明:灌溉可极显著提高大豆叶片的光合速率和大豆产量,交替隔沟灌45 mm的R4期光合速率、产量与交替隔沟灌60 mm差异不显著,而且土壤水分利用效率最高,从节水增产增效角度分析,交替隔沟灌溉45 mm的灌溉方式最佳.     

APSIM模型对宁夏海原地区草田轮作系统的适应性

为验证APSIM模型对宁夏海原地区草田轮作系统的适用性,基于10年生苜蓿(Medicago sativa)与小麦(Triticum aestivum)、谷子(Oryza sativa)草田轮作试验数据和同期气象资料,运用APSIM模型对系统进行了模拟。通过试错法和文献记载完成了苜蓿、小麦和谷子几个品种的参数本地化。用统计和图形校验方法评价了APSIM模型模拟结果的可靠性和准确性。结果表明,谷子-小麦-小麦(MWW)、小麦-谷子-小麦(WMW)、谷子-谷子-小麦(MMW)、谷子-小麦-谷子(MWM)、小麦-谷子-谷子(WMM)、小麦-小麦-谷子(WWM)6种轮作方式下产量实测值和模拟值的决定系数R2值范围在0.83至0.98之间,D值范围在0.94至0.99之间,表现出了良好的相关性和一致性。土壤含水量实测值和模拟值的决定系数R2值范围在0.52至1之间,D值范围在0.92至0.97之间,相关性和一致性表现良好。表明APSIM模型对宁夏海原地区苜蓿与小麦、谷子轮作具有较好的模拟能力,可以用来模拟分析该地区草田轮作系统生产潜力和土壤水分动态,对该地区气候变化影响下草田轮作的优化管理具有一定指导意义。     

玉米种衣剂配方数学模型筛选研究

采用二次回归旋转组合设计方法 ,对玉米种衣剂优化配方进行研究。通过利用计算机技术对试验数据进行处理和模拟寻优 ,建立了产量函数模型 ,筛选出产量≥ 975 0kg hm2 的最佳配方组合方案 ,并确定了置信域。     

宁南旱区苜蓿草地土壤水分消耗规律及粮草轮作土壤水分恢复效应研究

对宁南旱区不同生长年限紫花苜蓿草地土壤水分消耗及粮草轮作水分恢复效应进行了研究。结果表明:(1)随着苜蓿生长年限延长,在1￣6年内苜蓿草地土壤湿度下降迅速,产草量逐年上升,7年后土壤湿度下降趋于平缓,但苜蓿产草量下降迅速,表明苜蓿生长强烈耗水引起深层土壤干燥化,导致苜蓿生长逐渐衰败,苜蓿平均降水生产效率逐年下降;(2)苜蓿草地土壤垂直剖面可分为降水入渗恢复层(0￣200cm)、根系发达枯竭层(200￣500cm)和根系衰老缓耗层(500cm以下)三个层次。随苜蓿生长年限延长,苜蓿剖面的主要土壤干层逐渐上移,并且干层厚度呈现减小趋势;(3)耕翻的苜蓿茬后轮作粮食作物的年份越长,土壤水分恢复越好,实行草粮轮作的苜蓿最迟不超过生长的第10年。     

Effects of arrangement of surge-rootirrigation emitters on growth,yield andwater use efficiency of apple trees

Six-year old apple trees were selected for field experiment. The objective of this study was to obtain the reasonable arrangement of surge-root irrigation emitters in apple orchards. There were three factors: the buried depth H( 25,40,55 cm),the horizontal distance L( 30,40,60 cm) between the emitters and the trunk of the experimental tree,and the number of the irrigation emitters N( 1,2,4). The effect of the arrangement of surge-root irrigation emitters on the growth,yield and irrigation water use efficiency( IWUE) of apple trees were studied in Northern Shaanxi where the irrigation quota takes 60%-75% of the field water capacity. The results showed that the arrangement of emitters for surge-root irrigation had a significant effect on apple tree yield and IWUE,especially,the yield and IWUE reached 28 388. 17 kg/hm2 and 16. 83 kg/m3 in treatment T3,respectively. At the same L and N levels( T1,T2,and T3),the yield and IWUE in treatment T3 were the highest,and the yields in treatments T1 and T2 were decreased by 26.22% and 31.48%,while IWUE is reduced by14.02% and 18.12% compared with T3,respectively. At the same H and N levels( T3,T4,and T5),the yield and IWUE of apple trees were decreased with increasing L level. Especially,when L was 30 cm( T3),the yield and IWUE were the highest. The same L and H levels( T3,T6,and T7) could promote the growth of apple trees when N was 2( T3). Compared with treatment T3,it was found that the increment of new shoots was decreased by 8.07%-18.71%,and the fruit diameter was decreased by 5.41%-9.11%. Therefore,two emitters should be arranged symmetrically on both sides of an apple tree,each was buried at a 40 cm depth and 30 cm away from the trunk of the tree to effectively improve the yield and IWUE of the apple tree in mountainous areas in Northern Shaanxi.     

Effects of different soil conservation tillage approaches on soil nutrients,water use and wheat-maize yield in rainfed dry-land regions of North China

Excessive tillage compromises soil quality by causing severe water shortages that can lead to crop failure. Reports on the effects of conservation tillage on major soil nutrients, water use efficiency and gain yield in wheat (Triticum aestivum L.) and maize (Zea mays L.) in rainfed regions in the North China Plain are relatively scarce. In this work, four tillage approaches were tested from 2004 to 2012 in a randomized study performed in triplicate: one conventional tillage and three conservation tillage experiments with straw mulching (no tillage during wheat and maize seasons, subsoiling during the maize season but no tillage during the wheat season, and ridge planting during both wheat and maize seasons). Compared with conventional tillage, by 2012, eight years of conservation tillage treatments (no tillage, subsoiling and ridge planting) resulted in a significant increase in available phosphorus in topsoil (0–0.20 m), by 3.8%, 37.8% and 36.9%, respectively. Soil available potassium was also increased following conservation tillage, by 13.6%, 37.5% and 25.0%, and soil organic matter by 0.17%, 5.65% and 4.77%, while soil total nitrogen was altered by −2.33%, 4.21% and 1.74%, respectively. Meanwhile, all three conservation tillage approaches increased water use efficiency, by 19.1–28.4% (average 24.6%), 10.1–23.8% (average 15.9%) and 11.2–20.7% (average 15.7%) in wheat, maize and annual, respectively. Additionally, wheat yield was increased by 7.9–12.0% (average 10.3%), maize yield by 13.4–24.6% (average 17.4%) and rotation annual yield by 12.3–16.9% (average 14.1%). Overall, our findings demonstrate that subsoiling and ridge planting with straw mulching performed better than conventional tillage for enhancing major soil nutrients and improving grain yield and water use efficiency in rainfed regions in the North China Plain.     

Effect of tillage and crop on arbuscular mycorrhiza colonization of winter wheat and triticale under Mediterranean conditions

Large‐scale inoculation with arbuscular mycorrhizal fungi (AMF) is generally impractical in most regions and we have little understanding of the factors that determine inoculation success. Nevertheless, the ability to take full advantage of indigenous AMF for sustainable production needs to be developed within cropping systems. We used part of a long‐term field experiment to understand the influence of tillage and the preceding crop on AMF colonization over the growing season. Arbuscular mycorrhiza colonization rate was more affected by treatment (tillage or the combination of crop and preceding crop) than by the total number of AMF spores in the soil. Conventional tillage (CT) had a statistically significant negative effect (P ≤ 0.05) on spore numbers isolated from the soil, but only in the first year of study. However, the AMF colonization rate was significantly reduced by CT, and the roots of wheat, Triticum aestivum, L, cv. Coa after sunflower, Helianthus annuus L., were less well colonized than were those of triticale, X Triticosecale Wittmack, cv. Alter after wheat, but the affect of tillage was more pronounced than was the effect of crop combination. Under no‐till there was a significant increase in AMF colonization rate throughout the sampling period in both wheat and triticale, indicating that the extraradical mycelium previously produced acted as a source of inoculum. In general, triticale showed greater AMF colonization than wheat, despite the preceding crop being less mycotrophic. Under these experimental conditions, typical of Mediterranean agricultural systems, AMF colonization responded more strongly to tillage practices than to the combination of crop and preceding crop.     

Impact of organic residues and mineral fertilizer application on soil–crop system: II soil attributes

The effects of crop residues alone (Cr⁺) or combined with inorganic fertilizer (FCr⁺) sewage sludge (SS) and humentos (H) on soil properties were studied in a five-season wheat–guar rotation. Incorporation of Cr⁺ and SS significantly decreased pH by 5–9%. Highest organic carbon (OC) was observed in SS plots, whereas Cr⁺ resulted in values threefold that of the control. The added effect of Cr⁺ (46%) combined with fertilizer on total nitrogen (TN) was greater than Cr⁺ by 28%. The fraction of total residue N mineralized was 71%, whereas net N mineralized in Cr⁺, SS, H and FCr⁺ plots at 0–20 and 20–40 cm depths were 39.8, 52.3, 11.4, 66.7 mg kg^?1 and 21.2, 27.9, 8.2, 41.2 mg kg^?1, respectively. Integrated application of Cr⁺ with fertilizer had a synergistic effect on P content (3.49–3.69 units), but soil levels has never exceeded 13 mg P kg ^?1. Sole Cr⁺ significantly increased topsoil cation-exchange capacity (CEC) compared with the control treatment (9.39–21.59%). Application of SS, FCr⁺ and Cr⁺ significantly increased water-holding capacity and decreased bulk density by 9–15% and 8–9%, respectively, suggesting that such practice can restore the productivity of degraded soils and improve crop yields.