温,湿度条件及不同种子处理对棉籽吸胀冷害的影响

棉籽在4－5℃条件下吸水，发生吸胀冷害的程度随吸水速度的加快而减轻，随吸水时间的延长而加重；在10-12℃、18－20℃的水中吸水分别超过16小时、12小时，会因吸水时间过长使部分棉籽的种子活力降低，而使正常发芽率降低。经温汤浸种和预冷处理的棉籽能耐72小时0－5℃的低温，且耐较长时间低温的能力强于干籽与晾干籽；干籽、晾干籽能耐24小时0－2℃的低温，且干籽耐短时间低温的能力强于湿籽。     

A comparative evaluation of the Mississippi soil test method for determining available manganese,magnesium, and calcium

Abstract

Soil Samples (72) were collected from the Delta, Hill, and Northeast Blackland areas of Mississippi. Chemical analyses for manganese, magnesium, and calcium were made using the Mississippi Soil Test Solution (MSTS) and several other extracting solutions chosen for comparison. For the determination of available soil manganese, the MSTS proved to be as effective as either the Double Acid (0.025 N HCl in 0.05 N H₂SO₄) or 0.1 N H₃PO₄. The acid extractants removed more manganese than 1 N NH₄OAc (pH 7.0) and therefore included forms that are not exchangeable. The methods studied for magnesium determinations were equilibrium extraction with 1 N NH₄OAc, MSTS, Double Acid, 0.25 N CaCl₂, and leaching with 1 N NH₄OAc. All methods were highly correlated and therefore would be equally effective in determining available soil magnesium. Since MSTS and equilibrium extraction with 1 N NH₄OAc removed similar amounts of magnesium from the soil, the same calibration can be used. Calcium determinations were made using equilibrium extraction with 1 N NH₄OAc, MSTS, and Double Acid, and by leaching with 1 N NH₄OAc. All methods proved effective in measuring available soil calcium on acid soils.     

塑棚蔬菜气象信息服务系统

分析了木地塑棚蔬菜的气候背景，品种选择，温度指标，生产管理，无公害蔬菜生产等方面的状况。研究了大风，强降温，大雪，连阴天等灾害天气对塑棚蔬菜生产造成的影响以及相应的预报方法，据此开发了塑棚蔬菜气象信息服务系统，包括气象信息，灾害天气预报以及防御对策等。     

Excessive application of nitrogen and phosphorus fertilizers induces soil acidification and phosphorus enrichment during vegetable production in Yangtze River Delta,China

Intensive vegetable cultivation has developed very rapidly in China, and investigation of current soil nutrient problems in vegetable fields and their potential environmental risk is important for local soil nutrient management strategies. Three hundred and sixty‐six soil samples were collected from greenhouse vegetable fields, open vegetable fields and rice/wheat rotation fields in southern Jiangsu Province, the most intensive vegetable‐producing areas in Yangtze River Delta, China, for the analysis of their soil fertility status. Soil acidification and P enrichment were the main problems identified in this area of vegetable production, with about 20 and 17% of the open and greenhouse vegetable field soils, respectively, being extremely acid with soil pH values below 5.0. In contrast, no soils under rice/wheat rotation fields were as acidic. Percentages of sites with Olsen‐P concentrations < 90 mg/kg were 61, 85 and 0% for soils growing greenhouse vegetable, field vegetable and rice/wheat, respectively. The nitrogen (N) surplus for vegetable fields exceeded 170 kg/ha/crop, and the phosphorus (P) surplus exceeded 40 kg/ha/crop. Thus, current vegetable production leads to potential environmental risks of N and P pollution of nearby aquatic bodies. Insufficient supplementation with potassium fertilizers was found in some vegetable fields. Several ameliorative measures are proposed.     

Plant Regeneration from in vitro Cultured Anthers of Black Mustard (Brassica nigra Koch)

Anthers of Brassica nigra, excised from fresh as well as cold-pretreated (3 days at 3 ± 2°C) buds cultivated on modified B₅ medium (Gamborg et al. 1968) containing sucrose level varying from 2 % to 10 %, along with 1O^?6M BAP (benzylaminopurine) and 9 × 10^?6M 2,4-D (2,4-dichlorophenoxyacetic acid), developed calli and/or embryos. The latter response was observed only in anthers reared on media containing 6 % or higher levels of sucrose. On media containing two or four per cent sucrose, the anthers produced calli, exclusively. The growth of embryos was inhibited or else they started callusing if left on the media containing higher levels of sucrose. However, on transfer to MS medium (Murashige and Skoog 1962), containing 2 % sucrose, embryos started callusing and subsequently a few secondary embryos differentiated. Such embryos were sub-cultured on MS + 5 × 10^?6M BAP + 2 % sucrose, wherein numerous shoots developed from embryos. The shoots were rooted by transferring to a medium containing 5 × 10^?6M NAA (naphthalene acetic acid). Within two months of culture, some of these plants started flowering in vitro.     

堆肥预处理对松木屑厌氧发酵的影响

针对目前针叶类林木松树厌氧发酵前预处理效果差、成本高的问题,在添加食品废弃物的条件下,研究好氧堆肥方法对松木屑(6.35 mm、9.53 mm和12.70 mm)和食品废弃物混合物料的预处理效果,以及对后续干式厌氧发酵过程的影响。研究结果表明,好氧堆肥过程对松木屑的预处理效果明显,但随着松木屑粒径的增大预处理效果降低;经堆肥预处理后物料的厌氧发酵原料的VS产气率均维持在199~215 L/kg范围内,约为未预处理组的1.4倍,而且发酵后物料中的VFA总量均维持在24.5左右,约为未堆肥预处理组的1.5倍,后续产气潜力更大。     

微氧预处理对有机废水厌氧消化产甲烷的影响

为了考察微氧预处理对有机废物厌氧消化产甲烷过程的影响,论文以合成废水为试验材料进行了试验研究。结果表明,在厌氧消化反应前进行一定时间的微氧预处理,可以强化水解产酸菌的作用,促进有机底物的水解酸化,从而有效促进甲烷的产生。微氧预处理4 h可以提高甲烷产量28%,提高最大产甲烷速率57.5%。10 h的预处理则对产甲烷菌具有毒害作用,甲烷产量显著降低,预处理时间过短,促进效果不明显。最佳的预处理时间为4～6 h。微氧预处理在控制好处理时间时可促进有机物水解酸化,因此可应用于复杂有机物如厨余垃圾等的厌氧发酵。     

一体化秸秆沼气发酵反应器设计

针对秸秆沼气发酵过程中存在的秸秆亲水性差、易结壳及进出料难等问题,设计了秸秆沼气发酵反应器。反应器采用两相分离发酵一体化结构,通过沼液循环回流,使秸秆始终处在高水分区域环境,营造良好的厌氧微生物的生存环境,同时在固液两相分离和沼液回流过程中使秸秆在反应器内形成上下流动的状态,从而达到自动搅拌和秸秆破壳功能。另外,在进料口处设置预处理罐,对进料口进行水封,并对物料进行预处理。该反应器结构简单、运行稳定、操作方便、节省动力,实现了预处理、自动破壳及两相一体化秸秆高效发酵沼气的功能,对促进秸秆综合利用、带动秸秆沼气工程的推广具有重要意义。     

酸碱预处理对三球悬铃木落叶同步糖化发酵产氢的影响

对三球悬铃木(俗称法国梧桐)落叶酸碱预处理及其同步糖化发酵产氢工艺进行实验研究,利用修正的冈珀茨模型(Gompertz model)对产氢曲线加以拟合,以累积产氢量和产氢速率为考察指标,研究不同酸碱预处理方法(添加质量分数为2%、4%、6%、8%的H2SO4和Ca(OH)2)对三球悬铃木落叶光合生物产氢性能的影响规律,优化出最佳酸碱预处理工艺条件为:稀酸预处理后的落叶试样的产氢性能优于氢氧化钙预处理后的落叶试样,其中H2SO4质量分数为4%时处理效果最佳,发酵产气中的氢气最大体积分数达66.34%,累积产氢量为369 m L,最高产氢速率11.03 m L/h。稀酸处理液可以实现3次有效回收利用。     

等离子体活化水在种子播前处理中的研究进展

种子播前处理具有打破种子休眠、降低病虫害和促进作物生长的作用,是农业生产的重要环节。等离子体活化水(PAW)种子处理作为一种新兴的物理种子处理技术,因绿色环保、操作简单和批量均匀处理等优点而受到广泛关注。PAW富含各类活性粒子,具有优异的生物活性,能够促进种子萌发、减少种子表面病菌,应用前景广阔。本文在阐述了等离子体种子处理技术原理的基础上,综述了液相等离子体放电机理、PAW生产系统及存储方式,并探讨了PAW在促萌发和表面消毒的机理,总结了 PAW 在农业生产中的优势和局限,旨在为PAW种子处理的应用和推广提供参考。