Ion interactions in calcium‐efficient and calcium‐inefficient tomato lines 1

Two Ca‐efficient and 3 Ca‐inefficient tomato lines selected on the basis of dry matter production, Ca concentrations in tissues, and severity of Ca deficiency symptoms were grown in nutrient solutions containing 6 levels of total Ca ranging from 15 to 365 mg in 70 mg increments. All lines responded to increased Ca supply by increasing in dry weight and by accumulating Ca. The critical Ca concentrations in the shoots were 0.25% and 0.40% on a dry weight basis for the efficient and inefficient lines, respectively. Concentrations of Ca, K, Mg, P, and NO₃ ^‐ were lower in shoots and except for Mg were lower in roots of efficient plants than in the inefficient plants. For all lines as more Ca was available in the media and as Ca increased in the shoots and roots, the concentrations of the nutrients other than Ca declined. The declines in concentrations of K and Mg were not due to dilution by higher dry matter production in the efficient lines relative to the inefficient ones, although the total accumulation of Ca, P, and NO₃ ^‐ did not vary with Ca supplied. Antagonism among cations may account for differences in efficiency among lines of tomato.     

Sorghum genotype differences to leaf “red‐speckling”; induced by phosphorus 1

Sorghum [Sorghum bicolor (L.) Moench] plants grown in nutrient solutions, sand, and soil under greenhouse or growth chamber conditions developed a lower leaf “red‐speckling”; which was induced by phosphorus (P). As P in solution increased, the intensity of the “red‐speckling”; increased. Although the severity of “red‐speckling”; was not directly related to leaf P concentration, leaves with more severe symptoms had higher P concentrations. KS35, ‘Martin’, and ‘Plainsman’ developed severe symptoms, CK60‐Korgi, SC369–3‐1JB, and TX415 developed intermediate symptoms, and NB9040 developed no symptoms when grown at relatively low levels of P (10 to 20 umol per plant). Organic sources of P induced more severe “red‐speckling”; than inorganic sources. The severity of “red‐speckling”; induced by P compounds followed the sequence of gyceryl > ethyl ammonium = phenyl > potassium dihydrogen > calcium meta > calcium dibasic > calcium tribasic > ferric > calcium pyro = ferrous = aluminum phosphates. “Red‐speckling”; on young sorghum leaves may be caused by excess P. This excess or toxic P “red‐speckling”; occurred at P levels lower than had normally been considered or expected.     

Effects of salt stress on nitrogen fixation,oxygen diffusion,and ion distribution in soybean,common bean,and alfalfa

The exposure of legume nodulated‐roots to 100 mM NaCl resulted in a rapid decrease in plant growth associated with a short‐term inhibition of both nodule growth and nitrogenase activity (C₂H₂ reduction=ARA). However, these NaCl effects varied among species, common bean being more sensitive than soybean and alfalfa. The higher sensitivity of common bean was associated with a higher accumulation of sodium (Na) and chlorine (Cl) in the nodules and only a small difference between salt‐treated and control plants of common bean in their responses of ARA to raising rhizosphere pO₂. By contrast, soybean and alfalfa plants showed a higher stimulation of ARA by pO₂ for the salt‐treatment than for the control. It is concluded that the intraspecific variation in short‐term inhibition of ARA by salt may involve the regulation of O₂ diffusion and the distribution of ions in nodules.     

不同茬口设施番茄栽培的根圈基质中酶活性与养分效应

研究了番茄设施有机基质栽培的正茬、迎茬、连茬根圈生物性状和理化性状的变化, 分析了不同茬口对番茄栽培基质中酶活性、有机质含量和主要养分含量的影响。结果表明, 番茄连茬栽培基质的蛋白酶、磷酸酶、脲酶和过氧化氢酶活性下降, 有机质、全氮、铵态氮、碱解氮、全磷、速效磷、全钾及速效钾等主要养分含量降低, 而正茬栽培对基质酶活性、有机质和主要养分含量的影响较小。基质酶活性与理化性质的相关性分析表明, 番茄有机基质栽培中, 连茬、迎茬和正茬条件下基质的化学性质与生物学性质密切相关, 从而导致了番茄连茬基质微生态环境的改变。所有指标的相关性中, 脲酶与有机质和主要养分含量的相关系数最大, 说明脲酶活性是影响基质有机质含量和主要养分的重要因子。各茬口中, 速效钾、速效磷、全钾和过氧化氢酶活性的可塑性指数均最大, 不同茬口基质各指标的可塑性指数表现为新基质的最大、正茬次之、连茬最小, 说明连茬基质不适宜于番茄生长, 而正茬基质的生物和理化性质与新基质差异不大, 适宜于番茄生长发育。     

社会规范、生态认知与农户地膜回收意愿关系的实证研究——以环境规制为调节变量

文中利用新疆697位农户的调查数据,以社会规范为前因变量,生态认知为中介变量,环境规制为调节变量,构建有调节的中介模型,研究了社会规范对农户地膜回收意愿的影响路径。结果表明:(1)社会规范对农户地膜回收意愿有显著的正向影响;(2)生态认知在社会规范和农户地膜回收意愿之间起部分中介作用;(3)环境规制中的经济补贴和经济惩罚正向调节"社会规范—生态认知—地膜回收意愿"过程的后半路径和生态认知的中介作用,而宣传教育的正向调节作用不显著。研究丰富和完善了农户地膜回收意愿影响路径,对践行农业清洁生产、推进地膜污染治理具有重要的启示作用。     

河南烟草连作状况调查及连作障碍解决对策研究

河南烤烟连作以4～5年为主。烤烟连作后病虫害加重,烟叶产量和品质下降等问题比较严重。目前研究认为烤烟连作障碍主要因为连作烟田矿质养分、微生物种类和数量、土壤中酶活性及自毒作用等方面发生了恶性变化,加重了烟草生产中病虫害发生,阻碍了烟株的生长发育。文章通过对目前河南烟区连作情况的调查,并结合已有的研究,从连作烟田消毒、种植模式、施肥模式、微生物菌剂修复等方面探讨了缓解乃至解决烟草连作障碍问题的措施。     

AM 真菌对大棚芦笋矿质元素吸收和营养品质的影响

将接种丛枝菌根真菌摩西球囊霉（Glomus mosseae,GM）的芦笋菌根苗定植在大棚内,研究菌根对芦笋植株生物
量、矿质元素吸收和产量品质的影响。结果表明：接种GM 的芦笋单株地上部鲜质量增加了45.57%,地上部干质量增加了
29.65%;拟叶叶绿素、类胡萝卜素含量和植株根系活力均显著增加;植株吸收N、P、K、Mg、Mn、Cu 的能力均有不同程度
地提高;嫩茎中芦丁含量和皂苷含量也显著提高。     

高山草甸草地牧草产量及其营养变化规律

高山草甸草地是青海省主要冬春放牧地，占冬春草地总面积的４７．９６％。对所测高山草甸草地实行全年封育，每月测定草地地上生物量和营养物质。测定结果表明：①牧草产量以８月份最高，９６．８２ｇ／ｍ＾２，翌年５月最低，２２．２５ｇ／ｍ＾２，全年呈单峰型，牧草营养物质总产量亦是如此规律，牧草粗蛋白质含量和粗纤维含量随牧草生长期的推移呈负相关（ｒ＝－０．８９５）；②冬春季节牧草经长时间的日晒、风吹，自然损失严重     

Export of Nutrients in Plant Biomass Following Harvest of Eucalypt Plantations in Kerala,India

Abstract

Pools of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) were examined in the soil and above-ground plant biomass at the end of a 7 year rotation at two E. tereticornis lowland sites and two E. grandis highland sites in Kerala, India. Potential export rates of these nutrients were also examined for different biomass removal scenarios from the plantations. Pools of nutrients were measured in the above-ground components of the tree crop, forest floor and understorey, and in soil down to 1 m depth. At harvest, large quantities of biomass and nutrients are removed from eucalypt plantation sites, with the quantities of nutrients exported unlikely to be replaced through natural atmospheric and weathering inputs. Between 24 Mg ha^-1 and 115 Mg ha^-1 of biomass was exported in stem wood across the sites, and this increased to 40-145 Mg ha^-1 in scenarios where all of the branches, bark and understorey were also exported. Stem wood had the lowest concentration of nutrients and had a relatively low export of nutrient per kg of biomass. On average, 54 kg, 12 kg and 65 kg of N, P and K were removed per hectare in stem wood only, equivalent to 0.46%, 0.17%, and 6.7%, respectively, of above- and below-ground (to 1 m depth) site pools. Export increased to 194 kg, 30 kg, and 220 kg of N, P and K per hectare if the branches, bark and understorey were also removed (equivalent to 1.6%, 0.5% and 24.7% of above- and below-ground site pools down to 1 m depth). Export of Ca and Mg was also high, with an average of 88 kg and 11 kg of Ca and Mg removed per hectare if only the stem wood was taken (3.12% and 1.34% of total above-ground and exchangeable below-ground to 1 m depth), increasing to 501 kg ha^-1 and 66 kg ha^-1 if the branches, bark and understorey were also removed (21.7% and 11.3% of total above-ground and available below-ground to 1 m depth). Removals of this magnitude represent a significant proportion of site nutrient pools and have the potential to reduce future plantation productivity unless steps are taken to promote retention of biomass and nutrients on site and/or replacement of nutrients through fertilizer application.     

粉煤灰综合利用研究现状

指出了随着经济的快速增长和城市化进程的不断加快,电厂的粉煤灰排放量不断增加,其资源化利用已成为世界各国政府和专家学者极为关注的问题。结合粉煤灰的物理化学性质特点,探讨了粉煤灰在建筑、道路、污水处理、农业、催化反应等方面的一些应用新途径和应用现状。