叶面喷施镁肥对缺镁番茄养分吸收和分配的影响

针对近年来北方日光温室中栽培番茄缺镁普遍发生和日益严重的问题,研究了叶面喷施MgSO_4、Mg(NO3)2及不同施用量对秋冬茬缺镁番茄K、Ca、Mg吸收和分配的影响,以期为番茄缺镁的矫正提供科学依据。结果表明:(1)随番茄生育进程各处理番茄叶片Mg和K含量呈下降趋势,Ca含量先下降后基本稳定,其中,Mg和Ca以第1穗果膨大期到第2穗果膨大期下降幅度最大,降幅分别为17.8%和39.1%。(2)喷施Mg肥显著提高叶片中Mg的浓度及携出量,喷施含镁0.4%的MgSO_4·7H_2O溶液叶片镁含量及携出量较对照分别提高了1.55和1.78倍,而对根、茎和果实中Mg的浓度及携出量无明显影响;从产量上看,喷施含镁0.2%和0.4%MgSO_4·7H_2O及0.2%Mg(NO3)2·6H_2O溶液与不喷施相比产量分别提高了8.0%、8.9%和5.3%,但差异不显著。(3)土壤交换性K/Mg均大于适宜值,K、Mg养分比例严重失调,而石灰性土壤养分失调后叶面补施Mg肥,Mg从叶片向其他部位的转运有限,必须降低钾肥施用量,使养分平衡供应。     

喷施钙硅对设施春茬番茄根系生长、NPK吸收及产量和水分利用的影响

以番茄品种鑫语为试验材料,在开花盛果期喷施含Ca(NO_3)_2、Ca(H_2PO_4)_2、KSiO_4、Ca(NO_3)_2+KSiO_4及Ca(H_2PO_4)_2+KSiO_4的悬液,探讨钙硅单一及配合施用对设施春茬番茄根系生长、NPK吸收、产量及水分利用率的影响。结果表明:喷施钙硅悬液显著促进番茄根系生长及发育,显著促进根系和果实磷钾吸收;含钙悬液单独喷施处理的根系和果实氮吸收显著高于硅悬液及钙硅复配悬液;两种含钙悬液Ca(NO_3)_2和Ca(H_2PO_4)_2喷施处理取得最佳调控效果,与对照相比,分别使番茄增产9%和7%,水分利用率提升7、5.5 kg·m~(-3),喷施Ca(NO_3)_2+KSiO_4使番茄增产4.7%,水分利用率提升3.8 kg·m~(-3),喷施Ca(H_2PO_4)_2+KSiO_4和KSiO_4未取得显著的调控效果;含钙悬液单独喷施处理增加番茄产量与其促进根系发育及增加植株N吸收密切相关;两种含钙物质与KSiO_4对番茄产量的影响存在显著的交互效应,对产量的贡献呈:含钙物质含钙物质×KSiO_4KSiO_4。含钙悬液喷施技术简单高效,能实现番茄增产及生物节水能力提升。     

科学施肥小常识

1植物营养的基本特性 植物在生长过程中吸收各种养分的量是不同的。吸收多的称为大量元素吸收少的称微量元素。据科学家研究表明大量元素为9种（碳、氢、氧、氮、磷、钾、钙、镁、硫）。微量元素为7种（氯、硼、钼、铜、锌、铁、锰）。也就是说16种元素存在15种只差一种元素作物就不能生长。那么是不是植物体内构成的就是16种元素呢？     

水汽压差与钾素互作对高温下番茄营养吸收与光合特性的影响

空气水汽压差（VPD）是植物水分运输的主要驱动力，影响作物对营养的吸收。探究不同VPD与钾素对高温下作物营养元素的吸收与光合特性的影响对夏季番茄合理施肥与环境管理具有重要意义。试验以‘金棚14-6’番茄为试材，采用盆栽方式，设置2个VPD水平（高VPD、低VPD）与3个钾素水平 (2、4、8 mmol·L^-1)共6个处理，分析了VPD与钾素互作对高温下番茄幼苗氮磷钾吸收、气体交换参数、光合和CO₂响应等的影响。结果表明：与高VPD相比，降低VPD会对番茄植株各器官的氮、磷、钾含量产生稀释效应, 但随着钾素水平的提高，氮、磷、钾的积累量均会显著增加，各元素积累量分别增加了99.6%、98.1%和44.7%（氮），57.4%、50.4%和51.6%（磷），145.9%、71.5%和30.6%（钾）。在低VPD下，中钾水平更有利于干物质和氮、磷、钾元素的积累，其叶片的氮素积累量和叶片水势显著高于其他5个处理；且低VPD下的植株具有较大的光照、CO₂浓度适应区间和高光合及相关参数，包括光合速率P_n、气孔导度G_s、光饱和点LSP、表观量子效率AQY、暗呼吸速率R_d和初始羧化效率CE等，且均在中钾水平时取得最大值；同时蒸腾速率T_r、光补偿点LCP与光呼吸速率R_p等均显著降低。综上可知，高VPD下高钾水平和低VPD下中钾水平提高了番茄的光合性能、氮磷钾元素吸收量和干物质积累量，可作为夏季高温施肥与环境管理指标。     

干旱胁迫和钾肥对油菜苗期生物量和水分利用特征的影响

以西南地区广泛种植的8个油菜品种为材料,研究不同水分和钾肥处理对油菜苗期生长和水分利用特征的影响。结果表明,与正常水分处理(W2)相比,干旱处理(W1)严重抑制油菜苗期生长,生物量在干旱期和复水期分别降低了43.7%和36.3%;干旱胁迫下提高钾肥水平显著促进了油菜生物量的提高(P0.05),油菜生物量在干旱和复水期较低钾处理分别提高了16.1%和11.9%。与W2处理相比,W1处理的水分利用效率在干旱期和复水期分别下降了8.0%和17.8%,差异达显著水平(P0.05);与低钾水平相比,干旱胁迫下提高钾肥水平可促进水分利用效率的提高,在干旱期和复水期分别提高了14.3%和6.4%,在干旱期差异达显著水平(P0.05)。水分利用效率与蒸腾效率呈极显著正相关,与蒸发/蒸腾比呈极显著负相关(P0.01)。干旱胁迫下,油菜蒸腾效率显著提高,而蒸发蒸腾量显著降低(P0.05),其中蒸腾量在干旱期和复水期分别下降了60.9%和35.3%,蒸发/蒸腾比大幅度提高,大部分的水分通过蒸发散失而非植株利用,导致水分利用效率降低。干旱胁迫下钾肥利用效率降低,钾吸收量减少;提高钾肥的施用水平,钾肥利用效率降低,但钾吸收量提高。对W1处理的各生理指标进行主成分分析,可提取出2个主成分,油研10、油研57和油研817具有较高的综合得分,在干旱胁迫下具有较大生物量、水分利用效率、蒸腾量、钾肥利用效率和钾吸收量,表现出较强的抗旱性。     

日光温室钾镁配施对土壤固相和液相钾、钙、镁分配及比例的影响

针对西北地区日光温室作物出现的缺镁问题,通过施用不同水平的硫酸镁肥及减少钾肥施用处理,探究钾、钙、镁离子在土壤固相和液相的分布及比例。得出以下结论:土壤液相镁浓度随着镁肥施用量的增加而显著增加,施用45 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理和施用90 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理镁浓度相比不施用MgSO_4处理分别增加26.64%、74.78%;相比不施用MgSO_4处理,施用镁肥后土壤液相Mg~(2+)占K~+、Ca~(2+)、Mg~(2+)总量的比例显著增加,施用45 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理、施用90 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理和施用90 kg·hm~(-2)MgSO_4(200 kg·hm~(-2)K_2O)处理分别增加32.03%、31.62%、32.84%;施用镁肥促进钾由固相向液相转移;相比不施用MgSO_4处理,施用45、90 kg·hm~(-2)MgSO_4处理土壤固相交换性钾含量分别降低15.78%、27.74%,差异达到显著水平;交换性钾饱和度分别降低13.39%、27.21%;液相钾浓度显著增加,分别增加18.84%、73.91%;K+占K+、Ca~(2+)、Mg~(2+)总量的比例显著增加,增幅分别为23.91%、31.21%;土壤固相K+/Mg~(2+)比例分别降低14.52%、26.61%,;土壤液相Ca~(2+)/Mg~(2+)比例显著降低,降幅分别为31.51%、32.29%;施用MgSO_4肥量相同,钾肥施用量减半,土壤液相钾浓度降低69.88%,K+/Mg~(2+)比例降低20.88%;施用镁肥对番茄具有一定的增产作用,并能促进作物对镁的吸收。     

呼和浩特地区施磷对春小麦养分吸收和生物产量的影响

内蒙古农业大学教学农场大田设施磷与不施磷两处理，分析研究春小麦不同生育期体内的氮、磷、钾含量、吸收量，干物质积累量和生物产量。结果表明，乳熟一蜡熟阶段是春小麦养分吸收和生物产量积累的最快时期，磷可提高植株体内氮、磷养分浓度，对其他养分浓度影响不是很明显。磷素有利于干物质积累，可以增加春小麦生物产量和籽粒中氮、磷含量，但对钾素的影响不明显。因此，在制定施肥方案时，应重视氮、磷、钾的合理配合，以满足春小麦“高产、优质、高效”生产的营养需要。     

间作和施磷对2种牧草生物量及氮磷吸收的影响

采用双因素随机区组田间试验设计，设置不同种植模式（单作和间作）和2个磷水平（不施P：P0；P：P75），研究柱花草与扭黄茅间作和施磷对牧草生物量、养分吸收的影响。结果表明：在株行距均为50 cm条件下，施磷提高了间作体系中扭黄茅生物量的30.10%和氮吸收量的21.51%，但减少了柱花草地上部生物量5.53%和氮、磷吸收量的3.73%和3.18%。2015年，相对扭黄茅地上部生物量，P75水平下，与柱花草间作显著高于扭黄茅单作31.00%（P<0.05）。与未施磷对比，施磷条件下，柱花草和扭黄茅间作地上部的生物量分别增加41.31%和52.68%。2个磷水平下的土地当量比（LER）、间作系统生产力（SP）及牧草种间竞争能力（A）无明显差异（P＞0.05）。在间作系统中，相对柱花草，其与扭黄茅种间竞争能力小于0，说明柱花草在间作系统中为弱竞争作物。氮磷吸收方面，2015年，P0和P75水平下，间作体系中的柱花草氮、磷吸收量显著低于柱花草单作67.74%（P0）和67.19%（P75）（P<0.05），扭黄茅氮吸收量高于扭黄茅单作5.79%（P0）和44.28%（P75），而磷吸收量高于单作13.80%（P0）和6.61%（P75）。     

北方寒区日光温室冬季基质袋培番茄蒸腾量模拟

北方寒区日光温室冬季生产基本无通风，为了探寻室内弱光、高湿、低温及低风速环境下的番茄蒸腾量模拟模型，基于Penman-Monteith（P-M）方程及适应此特定环境的边界层空气动力学阻力、气孔平均阻力、土壤热通量等参数模拟了温室长季节栽培番茄（Lycopersicon esculentum Mill）单株的蒸腾速率并进行了试验验证，揭示了蒸腾速率与净辐射、饱和水汽压差的日变化规律，确定了蒸腾速率与植株上方净辐射的定量关系，检验了土壤热通量取值对蒸腾速率的影响。结果显示：2017-12-11—2018-01-03室内太阳总辐射最大值367 W·m^-2、夜晚及阴天相对湿度接近100%、室内风速接近0 m·s^-1的情况下，单株植株边界层空气动力学阻力变化范围晴天为147~438 s·m^-1，阴天为 211~365 s·m^-1；气孔平均阻力晴天69~1 506 s·m^-1，阴天132~1 151 s·m^-1；P-M方程模拟的单株番茄逐时蒸腾速率在晴天、阴天中午的平均值分别为0.06、0.02 mm·h^-1，模拟值与实测值比较，平均相对误差约为10%。研究还表明，单株番茄上方净辐射量的43.5%通过蒸腾作用转化为潜热；试验环境下，土壤热通量的取值变化对蒸腾速率影响不大。研究确定的蒸腾速率估算模型可为北方寒区冬季日光温室基质袋培番茄蒸腾量估算以及水分管理提供参考。     

钙、镁离子对烟草花叶病毒侵染的抑制作用

用珊西烟半叶法接种，测定了钙、镁离子以及离子螯合剂（EDTA）等对TMV浸染的抑制作用。结果高浓度的钙离子或镁离子溶液与等体积的TMV稀释液混合接种，显著地抑制病毒的侵染（抑制率高达80％─90％）；而且处理半叶上的枯斑直径小于对照，用ELSA方法检测病毒明显减少。接种前、后间隔一定时间使用钙、镁离子，抑制率仍在50％─90％；EDTA的作用依赖于叶片生理状态。说明植物、病毒与此二离子间存在复杂的相互关系。     

Root length density distribution and associated soil water dynamics for tomato plants under furrow irrigation in a solar greenhouse

Furrow irrigation is a traditional widely-used irrigation method in the world. Understanding the dynamics of soil water distribution is essential to developing effective furrow irrigation strategies, especially in water-limited regions. The objectives of this study are to analyze root length density distribution and to explore soil water dynamics by simulating soil water content using a HYDRUS-2D model with consideration of root water uptake for furrow irrigated tomato plants in a solar greenhouse in Northwest China. Soil water contents were also in-situ observed by the ECH_2O sensors from 4 June to 19 June and from 21 June to 4 July, 2012. Results showed that the root length density of tomato plants was concentrated in the 0–50 cm soil layers, and radiated 0–18 cm toward the furrow and 0–30 cm along the bed axis. Soil water content values simulated by the HYDRUS-2D model agreed well with those observed by the ECH_2O sensors, with regression coefficient of 0.988, coefficient of determination of 0.89, and index of agreement of 0.97. The HYDRUS-2D model with the calibrated parameters was then applied to explore the optimal irrigation scheduling. Infrequent irrigation with a large amount of water for each irrigation event could result in 10%–18% of the irrigation water losses. Thus we recommend high irrigation frequency with a low amount of water for each irrigation event in greenhouses for arid region. The maximum high irrigation amount and the suitable irrigation interval required to avoid plant water stress and drainage water were 34 mm and 6 days, respectively, for given daily average transpiration rate of 4.0 mm/d. To sum up, the HYDRUS-2D model with consideration of root water uptake can be used to improve irrigation scheduling for furrow irrigated tomato plants in greenhouses in arid regions.     

Effects of foliar sprayed calcium sources onTomato mosaic virus (ToMV) infection in tomato plants grown in greenhouses

Spray solutions containing 0.3% Ca which were prepared from four different calcium sources were foliar-sprayed on greenhouse-grown tomato plants, infected with theTomato mosaic virus Tobamovirus (ToMV) or not. ToMV-infected and uninfected control groups were sprayed with distilled water. Growth and macronutrient (N, P, K, Ca and Mg) composition of tomato plants as well as virus concentration and its relative infectivity were investigated in treated and untreated plants. The Ca sprays were applied three times: on the same day as inoculation, and 15 and 30 days after inoculation. Virus concentration in tomato plants generally decreased with foliar-sprayed Ca. Virus concentration (DAS-ELISA absorbance) was reduced by foliar-sprayed Ca, but plants remained infected. At the same time, tissue Ca concentrations increased significantly with foliar-applied Ca, with the exception of CaNO₃·4H₂O+0.05M Na-EDTA. ToMV reduced the fresh and dry weights and Ca concentrations of tomato plants, but significantly raised P concentration in the tissue. Neither virus inoculation nor foliar Ca applications affected N and Mg concentrations in tomato plants. The foliar-applied Ca from all the sources gave K concentrations similar to those of control plants. http://www.phytoparasitica.org posting Jan. 26, 2007.     

湖北省设施番茄灰霉病发生规律及流行因子分析

为探索湖北省设施番茄灰霉病的发生规律,揭示不同流行因子与番茄灰霉病发生的关系。于2013-2016年在湖北省武穴市吴谷英村番茄种植基地选取代表性番茄大棚进行调查和取样检测,结果表明:湖北省设施番茄叶片和花朵带菌率变化起伏较大,带菌率分别为0～90.0%和0～100.0%;叶片带菌率在3月下旬到4月中下旬和5月中下旬是高峰期;花朵带菌率在4月中旬和5月中下旬达到高峰期,总体上花朵带菌率较高。番茄不同组织灰霉病的发病时间不同,叶片首先开始发病,花、果实、茎秆再逐渐发病,花朵和果实的发病率相对较高,叶片和茎秆发病率较低;花朵和果实发病率均在5月中旬至6月初达到最大值,茎秆发病率于5月下旬至6月上旬达到最高值,叶片无明显发病高峰期。果实、叶片、花朵和茎秆的发病率分别为0～42.0%、0～24.7%、0～100.0%和0～32.0%。番茄叶片发病率、花朵发病率、茎秆发病率和相对湿度均与果实发病率呈显著相关;通过预测模型检验表明相对湿度和叶片发病率所建模型预测值和实际值符合程度较好。在湖北省设施番茄大棚中,叶片发病率、花朵发病率、茎秆发病率和相对湿度对番茄果实发病影响最为显著,在防治过程中应及时摘除发病组织,调控棚内环境条件,预防灰霉病发生。     

Possible rôle of allelopathy in the competition between tomato, Senecio vulgaris L. and Chenopodium album L.

Summary. The allelopathic effect of Chenopodium album L. (fat-hen) and Senecio vulgaris L. (groundsel) on tomato ( Lycopersicon esculentum Mill cv. Ailsa Craig) plants was investigated under glasshouse conditions. A new technology was used to separate competitive from allelopathic effects. These experiments suggested that C. album had an effect on tomato through allelopathy. C. album leach-ates significantly reduced shoot fresh and dry weights and the accumulation of N, P, K, Ca and Mg of tomato shoots. No effect was found on the quantities of these elements in tomato roots. Leachate of five plants of C. album per pot was sufficient to reduce tomato growth. Addition of 10 or 20 g kg⁻¹ of C. album dried shoots to the soil mixture significantly decreased the fresh and dry weights of tomato plants. S. vulgaris leachates did not show significant effects on the growth or nutrient accumulation of tomato plants.     

Natural extracts from pepper,wild rue and clove can activate defenses against pathogens in tomato plants

Tomato is an important species grown in many countries, either in fields or greenhouses. Despite decades of improvement, it is still susceptible to diseases, thus requiring the use of chemical pesticides, especially in greenhouses. Nevertheless it is imperative to reduce the use of environmental-unfriendly phytochemicals and favor less toxic tools to fight pathogens. Plants possess elaborate mechanisms against diseases that can lead to resistance. In the present work, we investigate the induction of plant defenses by means of extracts from plants widespread and easy to find, also known for their antimicrobial properties. Aqueous extracts of pepper ‘Rocoto’, wild rue and ethanolic extracts of clove powder (whose inhibiting effect was assessed on Oidium sp. spores) were tested on tomato plants for their ability to induce expression of different defense genes (PRs and regulatory proteins) after spraying. As revealed by RT-qPCR, all extracts were able to induce mRNA accumulation of different PR and MAPK regulators for several hours upon treatment, with clove and wild rue being the strongest. This effect could also be reproduced in tomato plants after a second treatment, 15 days after the first. The same extracts were tested in tomato and tobacco plants via leaf infiltration, showing necrotic symptoms associated with the hypersensitive response, thus confirming the priming capacity of the extracts. The involvement of salicylic acid (SA) in these responses was verified by HPLC analysis and in SA-depleted transgenic tobacco (NahG). The results obtained suggest that natural antimicrobial extracts can be used to induce plant defenses and protect valuable crops. At the same time these low-cost extracts do not pose a threat to the environment or the farmer and can help reduce the farming costs, especially in developing countries.     

Populations of aphids, whiteflies and associated predators and parasites on different vegetables cultivated in plastic greenhouses

During 1996 and 1997, populations of aphids and whiteflies and their parasites were studied in plastic greenhouses under a chemical control program and in those free of pesticides. In the greenhouses free of pesticides, the parasite A. colemani destroyed 14.7% of the aphids. B. tabaci had no effect on the cucumbers during the spring cultivation. However, it attacked the autumn cultivation. The parasite E. mundus killed 30% of these nymphs. The parasite A. colemani parasitized up to 10% of aphids on tomato plants in greenhouses free of chemical pesticides. The parasite E. mundus killed 15.7% of whitefly nymphs. In greenhouses under a chemical pesticides program, aphids and whiteflies were found on the plants at the end of the plantation season, after the pesticide spraying had stopped. Although the pest population was low, the parasite A. colemani parasitized 8% of the aphid population. Whiteflies were not found on tomato plants in greenhouses under extensive pesticides use.