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181.
182.
灌溉水矿化度及盐分带入量对小麦相对产量影响的统计分析 总被引:1,自引:0,他引:1
在搜集、统计大量咸水灌溉试验资料的基础上,选取咸水充分灌溉条件下矿化度和小麦产量的完整对应数据103组,统计分析了灌溉水矿化度及单位面积盐分带入量对小麦相对产量的影响,结果表明,随着灌溉水矿化度的增加,小麦相对产量呈线性递减趋势,当矿化度大于1.0 g/L时,灌溉水矿化度每增加1 g/L,小麦减产约5.6%;与矿化度类似,随着单位面积盐分带入量的增加,小麦的相对产量也线性降低,盐分带入量每增加1000 kg/hm2,小麦的产量将减少约2%。进一步的检验结果显示,应用灌溉水矿化度及单位面积盐分带入量均可较为可靠地估算小麦的相对产量,估算相对误差基本可控制在16%以内。 相似文献
183.
M. Asaduzzaman M.A. Wahab M.C.J. Verdegem S. Huque M.A. Salam M.E. Azim 《Aquaculture (Amsterdam, Netherlands)》2008,280(1-4):117-123
The present research investigated the effect of carbon/nitrogen ratio (C/N ratio) control in ponds with or without substrate addition for periphyton development on production of giant freshwater prawn. C/N ratios of 10, 15 and 20 were investigated in 40 m− 2 ponds stocked with 2 prawn juveniles (5.023 ± 0.02 g) m− 2 with or without added substrates for periphyton development. The various treatment combinations of C/N ratio and periphyton substrate addition are abbreviated as ‘CN10’, ‘CN15’, ‘CN20’, ‘CN10 + P’, ‘CN15 + P’ and ‘CN20 + P’, P representing periphyton substrate. A locally formulated and prepared feed containing 30% crude protein with C/N ratio10 was applied. Tapioca starch was used as carbohydrate source for manipulating C/N ratio and applied to the water column separately from the feed. Increasing the C/N ratio from 10 to 20 reduced (P < 0.001) the total ammonia-nitrogen (TAN), nitrite–nitrogen (NO2–N) and nitrate–nitrogen (NO3–N) in water column and total Kjeldahl nitrogen (TKN) in sediment. The addition of substrates only influenced the NO2–N concentration in the water column (P < 0.001). Increasing the C/N ratio raised the total heterotrophic bacterial (THB) population in the water column, sediment and periphyton (P < 0.001). It also increased the dry matter (DM), ash free dry matter (AFDM), and chlorophyll a content of periphyton (P < 0.001). The lowest specific growth rate (SGR), the highest food conversion ratio (FCR), and the lowest protein efficiency ratio (PER) were recorded in treatment CN10 (P < 0.05). The addition of substrates did not influence size at harvest (P > 0.05) but improved the survival from 62.8 to 72% (P < 0.001). Increasing the C/N ratio from 10 to 20 increased the net yield by 40% and addition of substrate increased the net yield by 23%. The combination of C/N ratio control and substrate addition increased the net yield by 75% from 309 (CN10) to 540 (CN20 + P) kg ha− 1 (120 days)− 1. This 75% higher production concurred with (1) a lower inorganic nitrogen content in the water column, (2) a higher THB abundance supplying additional single cell protein to augment the prawn production, and (3) an improved periphyton productivity and quality. 相似文献
184.
Information about reproductive season, size at sexual maturity and size-dependent reproductive potentials is important for
efficient resource management. Such information is necessary to determine seasonal closures and minimum legal size limits.
To conserve resources of coconut crab Birgus latro, which are in danger of extinction due to excessive exploitation, their reproductive season, female size at functional maturity
and relationship between female size and reproductive potentials were investigated. The reproductive season started in early
June and ended late August, and females with higher reproductive potentials showed a tendency to spawn early in the reproductive
season. The prohibition of exploiting the resources during the reproductive season, especially early in the season, would
be appropriate for sustainability of high reproductive outputs. Fifty percent of investigated females matured functionally
at 24.5-mm thoracic length (TL). However, the size at which all females reached functional maturity was 32.3 mm TL, and there
was a wide variation in the size of functional maturity among individuals. We must determine minimum legal size by taking
the variation into account to allow all individuals to mate at least once before they are caught, which may prevent serious
depression in reproductive rate and genetic diversity. 相似文献
185.
提出了一种改进的积因子层次分析方法—积因子位次赋值数据求权重法,该方法采用算术平均数赋值代替专家打分,最大程度的避免了主观判断可能造成的决策失误。用该方法对影响黑龙江省粮食生产潜力的17个因素进行排序,结果与实际情况较吻合。 相似文献
186.
为了阐明不同水分条件下氮、磷对不同基因型小麦的水分生理指标的作用及其变化趋势,试验逸用6个不同基因型的小麦进化材料,研究了拔节期各基因型小麦的叶片保水力、叶水势、叶片膜透性与气孔导度。结果表明,当土壤水分充足时,施肥会提高叶片保水力、叶水势,降低叶片膜透性,增加二倍体小走的气孔导度,而降低六倍体小走的气孔导度。在水分胁迫下,施肥会提高叶片保水力,降低叶水势、叶片膜透性和气孔导度;而且随小麦染色体倍性从2n→4n→6n的进化方向,小麦叶片保水力、叶水势、叶片膜透性均先降低,然后又升高。 相似文献
187.
188.
郑麦9023是河南省优质小麦生产的主导品种。为了建立郑麦9023的优质高效生产技术体系,对该品种品质特性在河南省的地域性变化以及土壤养分、氮磷钾肥料、杀菌剂对该品种品质特性的影响进行了研究。结果表明:(1)郑麦9023的品质特性在河南省的北部地区可稳定达到优质强筋小麦国家1级标准,在中部地区总体上接近优质强筋小麦国家1级标准,在南部地区可以达到优质强筋小麦国家2级标准;(2)抽穗期土壤速效N的含量是决定郑麦9023品质水平的关键栽培因素,此时土壤速效N含量60mg/kg、80mg/kg和160mg/kg分别为郑麦9023品质达到亚强筋、强筋、超强筋的土壤N素临界值;(3)K肥对强筋品质特性具有正效应,而P肥对强筋品质特性具有负效应;(4)杀菌剂粉锈宁对强筋特性具有劣化作用,而多菌灵无此负作用。 相似文献
189.
190.