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Soil redistribution by erosive processes is a serious problem for the potato growing areas of Prince Edward Island. Studies were conducted to evaluate soil loss for three major soil types under two different cropping systems, at catenary sequences with five slope positions, using the 137Cs tracer method. Adjacent forest catenas were sampled to provide baseline 137Cs levels. Soil loss over time (1960–1990) on a specific mass (kg m−2 yr−1) basis was calculated by comparing the 137Cs at the same slope positions for the cropping system and adjacent forest site. The effects of land clearing and long-term cultivation were to increase both the depth and density of the Ap horizon, and decrease the total 137Cs on an area basis, in comparison to the forested sites. The average 137Cs in the forested sites for all three soil types was 3133 Bq m−2. Catena average soil loss across all soil types and slopes, for the 1960–1990 time period, was 21 and 38 Mg ha−1 yr−1 for the pasture and crop rotation (potato) rotations, respectively. Shoulder slope positions tended to have the highest 137Cs loss, which was suggestive of tillage erosion. 相似文献
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黑龙江省农作物冷害气候区划 总被引：7，自引：1，他引：6
在调查研究和科学实验的基础上,分析出符合黑龙江省实际的窕作物冷害指标和霜冻指标。延迟型冷害指标是随各地温度水平不同而改变的动态值,障碍型冷害是以水稻抽前第９天至第１１天,日平均气温连续３ｄ低于１８℃为指标。霜冻指标是以各地日平均气温稳定通过１０℃终日的８０％保证率日期为标准,用日最低气温≤０℃的初日去衡量,后者小于前者时测定义为早霜冻日期。为了有针对性的防御冷害,将黑龙江省划分为８个不同程序的冷害 相似文献
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Pal RK Ahmad MS Roy SK Singh M 《Plant foods for human nutrition (Dordrecht, Netherlands)》2004,59(2):67-72
Guava (Psidium guajava) fruits of cv. L-49 with individual shrink wrapping using 9 LLDPE film could be successfully stored up to 12 days at ambient and 18 days in evaporative cool chamber with negligible loss in vitamin C content. The untreated fruits lose 25–30% of ascorbic acid within 1week after harvest. Delay in senescence and metabolic activities as supported by less changes in soluble solids, sugars, acidity, respiration, and ethylene evaluation rate was also observed in individual shrink wrapped fruits in cool chamber. The spoilage of fruits by Fusarium rots was significantly less in cool chamber in individually shrink wrapped fruits followed by Sta-fresh treatment. Sta-fresh was more effective in cool chamber than ambient. Individually stored wrapped fruits scored a better value of sensory score than Sta-fresh under both the storage condition. 相似文献
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河北接坝冷凉地区,被省政府列为无公害时差蔬菜生产基地。蔬菜产品数量、质量和市场占有率均有较强优势。但是,通过对时差蔬菜产业现状分析,仍然存在时间差未发挥优势、品种单一,科技含量低,营销体系不健全、产品精深加能力差、集约化生产能力低等制约因素。因此,必须采取加大新品种、新技术引进推广力度,加大投入和招商引资力度,强化监管部门的职能和推广综合化服务先进模式,加强流通体系建设,实现规模化、标准化、系列化生产经营模式,增强品种意识,形成品牌优势等策略。完善中介组织,创办产业协会,通过政府扶持,开通绿色通道,促进时差蔬菜产业发展。 相似文献
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通过了解冷季型草坪草的特性,研究冷季型草坪草在夏季的生长状况和一些相关生理指标,找出冷季型草坪草夏季休眠的原因和耐热性机理,从而推广冷季型草坪草在园林绿地中的广泛应用,促进我国园林绿化事业的迅猛发展。 相似文献
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草地早熟禾在持续高温（37～38℃）胁迫下表现为叶绿素相对含量下降,POD酶活性在处理2d时表现为下降,4d及4d后则明显提高。耐热品种较不耐热品种的叶片POD酶活性无论是适温（25℃）还是高温（38℃）下一般均较高。热境下有较高的POD酶活性可能是植株体耐热的主要原因之一。 相似文献
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大豆低温冷害试验研究报告 总被引：3，自引：0，他引：3
本试验于1985—1986年,用盆栽,在大豆不同生育时期以人工控制温度的方法进行低温处理。试验结果指出:低温处理使大豆植株生长缓慢,生育时期延迟,产量下降。低温处理的温度越低,处理的时间越长影响越重。大豆花芽分化期是大豆生理上的低温冷害关键期。该阶段对低温处理最敏感,产量大幅度下降,主要是荚数和粒数减少,空秕荚多,百粒重轻等综合因素所致。低温处理使大豆花荚败育。雌蕊遭受冷害也会阻碍结荚。低温处理大豆还使子粒加重病害。因此,必须注意防御低温冷害,才能确保大豆高产稳产质佳。 相似文献
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E. van Rijn A.J. Termorshuizen A.H.C. van Bruggen 《Soil biology & biochemistry》2007,39(11):2743-2749
Compost can have a disease suppressive effect, but compost research is constrained by the fact that repetition of experiments with a similar batch of compost is impossible, since storage affects the organic material including the microbial communities. The objective of this study was to test the hypothesis that differential changes in microbial community structure and associated microbial activities after various storage methods (drying, freezing and cooling) lead to differential changes in the disease suppressive ability of compost material with respect to Fusarium oxysporum f. sp. lini induced by mixes of composts with peat substrate (20/80%, vol./vol.). A significant (P<0.0001) storage method × compost interaction was found with respect to suppression of Fusarium wilt of flax, indicating that the effect of storage type on disease suppression is compost-dependent. For seven composts storage had no (13 cases) or a significantly positive effect (eight cases) on disease suppression and for 1 compost there was a significant negative effect of storage on disease suppression. Significant changes in microbial activity and 16S-rDNA DGGE banding patterns of the composts were observed as a result of all tested ways of storage and these changes could be related to changes in disease suppression: relatively strong changes in microbial activity and bacterial composition due to storage had a relatively strong effect on disease suppression. The cool storage treatment (4 °C) resulted in the least deviation in disease suppression from the fresh compost, although the freezing treatment gave the most reliable results with the lowest standard deviation. 相似文献