不同时期施锌对旱稻籽粒锌积累的影响

为了探明不同时期施锌肥对旱稻籽粒锌积累的影响,在田间条件下对两个旱稻供试品种(巴西陆稻和旱稻502)进行不同时期施锌肥(100 kg/hm~2 ZnSO_4·7H_2O)处理(基施或花前7 d土壤追施),收获期对旱稻各器官锌含量进行测定和分析.结果表明,与对照(未施锌)和基施锌肥相比,花前7 d追施锌肥能显著增加地上部生物量和籽粒产量.施锌肥两处理均显著提高了旱稻地上部锌积累量.与基施锌肥相比,花前7 d施锌肥更能增加旱稻糙米中锌的含量,但在巴西陆稻上两种施锌方法对籽粒产量的增加均不显著.     

磷锌配施对花生生理特性、产量及品质的影响

协调磷-锌配比是作物达到最佳产量和质量的保障。采用大田试验,在豫南花生主产区高磷低锌的砂姜黑土上,研究了不同磷、锌配比对花生抗氧化特性及产量、品质的影响。结果表明,磷锌配施对花生生理特性产生一定影响,相同磷用量下,施锌比不施锌显著提高了花生叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)活性、生长素、可溶性糖和可溶性蛋白质含量,降低花生叶片丙二醛(MDA)含量;相同锌用量下,随磷用量的增加,花生叶片的SOD和POD活性先增高后降低,MDA含量先降低后增加,生长素含量无显著变化,可溶性糖和可溶性蛋白质含量也表现出先增高后降低的趋势,但处理间差异呈显著或不显著。对花生产量和品质来讲,与不施肥相比,磷锌单独或配施均在一定程度上提高了花生产量、粗脂肪及脂肪酸组分,且磷锌配施效果优于二者单独施用,其中90 kg/hm~2磷肥与60 kg/hm~2锌肥配施处理的产量最高,增产率达24.1%,增产原因可能是提高了花生的抗氧化能力,增加了单株饱果数和饱果重。双因素方差分析结果显示,磷对花生株高、侧枝长、单株饱果数、单株饱果重和产量影响显著;锌仅对单株饱果数和饱果重及产量影响显著;磷-锌交互作用对花生株高影响显著,对产量及其构成因素和品质影响不显著。综上,磷锌配施可以改善花生的生理特性,提高花生产量和品质,但高量磷与锌肥配施却不利于花生抗氧化能力、产量和品质的提高。在豫南花生主产区,建议多补充锌肥,少用磷肥。     

低锌旱地施锌方式对小麦产量和锌利用的影响

西北地区是我国典型的旱地低锌区。本文选择黄土高原中部两个典型地点,通过田间试验,在两个施氮水平下,研究了不施锌、 土施锌、 叶喷锌和土施+叶喷锌4种方式对冬小麦产量、 锌的吸收和累积以及锌肥利用效率的影响。结果表明,不同施锌方式对小麦产量均无显著影响,但均提高了小麦子粒锌含量,提高幅度因施锌方式而异。与不施锌相比,叶喷和土施+叶喷锌肥可使小麦子粒锌含量提高40%左右,平均达到 40 mg/kg;单独土施锌肥虽使土壤有效锌提高3倍左右,但子粒锌含量无显著变化。叶喷锌肥的锌利用效率远高于土施和土施+叶喷处理,每公顷喷施1 kg锌可使小麦子粒锌含量提高6.70~13.04 mg/kg;子粒锌利用率为6.02%~9.40%, 达到土施锌肥的80倍左右;总锌利用率为19.78%~30.91%,是土施锌肥的132~221倍。施氮水平对小麦产量及锌肥利用效率均无显著影响。可见,在旱地低锌区,与土施锌相比,叶喷是更加经济有效、 环境友好的锌肥施用方式,是提高小麦锌营养品质切实可行的措施。     

全营养滴灌施肥对贺兰山东麓酿酒葡萄 光合生理特征及产量与品质的影响

为探讨全营养滴灌施肥对贺兰山东麓酿酒葡萄光合生理及产量、品质的影响,提出产质协同的营养调控技术。于2019—2021年采用单因素随机区组设计,设置常规施肥(CK)、CK+Si (T₁)、CK+Ca(T₂)、CK+Si+Ca(T₃)、CK+复合微肥(T₄)、CK+全营养肥(T₅)6个处理,研究中微量元素复配对酿酒葡萄光合特性、产量及其组成、品质等的影响。结果表明：与CK处理相比,T₁可显著提高酿酒葡萄叶片的净光合速率、气孔导度和叶绿素SPAD值,且分别提高了18.53%、13.63%和5.93%;配施中、微量元素均能提高酿酒葡萄的产量指标,且多元复配效果优于单元配施。T₅处理较CK处理相比,酿酒葡萄粒径、单果重、单穗长分别增加了6.26%、19.13%、51.56%;T₃处理下酿酒葡萄产量最高,为5576.35 kg/hm²;较CK处理相比,T₃处理下酿酒葡萄可溶性固形物...     

锌肥品种与施用方法对水稻产量和锌含量的影响

【目的】 鉴于在缺锌土壤上施用锌肥不仅可提高水稻产量,而且也能显著提高水稻籽粒锌含量,本研究旨在揭示不同品种锌肥和施用方法在提高水稻产量和籽粒锌含量方面的差异。 【方法】 以水稻品种‘镇稻 11 号’为供试材料,于 2011 年 5 月至 2012 年 11 月在大田条件下设置 4 组试验:试验 1,富锌稻种的生产制备与籽粒锌含量的染色鉴定试验,设水稻常规种植(CK)和生育期连续喷施 5 次硫酸锌(ZnSO₄·7H₂O,Zn) 2 个处理;试验 2,不同品种锌肥土壤施用试验,设不施锌肥对照(S1)、土施 ZnSO₄·7H₂O (S2)、土施氮锌复合肥(Urea-Zn,S3)、土施磷锌复合肥(Mosaic-Zn,S4)、土施钾锌复合肥(Kali-Zn,S5)、富锌种苗移栽(S6)和 ZnSO₄·7H₂O 蘸秧根移栽(S7) 7 个处理;试验 3,不同品种锌肥叶面喷施试验,设不施锌肥对照(F1)、孕穗期喷施 ZnSO₄·7H₂O (F2)、开花期喷施 ZnSO₄·7H₂O (F3)、孕穗期和开花期各喷施 ZnSO₄·7H₂O (F4)、开花期与农药一起喷施 ZnSO₄·7H₂O (F5)、开花期喷施 Kali-EPSO-Zn(F6)和开花期喷施 ADOB-IDHA-Zn(F7) 7 个处理;试验 4,富锌稻种育苗种植比较试验,设常规稻种(CK-grain)和富锌稻种(Zn-grain)育苗种植 2 个处理,研究其对水稻产量及构成、各器官(叶片、茎秆和籽粒)锌含量和累积分配的影响。 【结果】 1) 在水稻生育期进行叶面高浓度和高强度的喷锌方式可制备富锌稻种,且可采用双硫腙(DTZ)染色直观鉴定籽粒锌含量。2) 施用锌肥显著提高水稻产量和锌含量,且不同锌肥品种和施用方法间差异显著。3) 土壤施锌各处理平均增产效果显著高于叶面喷锌 5.2%;与土壤施锌处理相比,叶面喷锌各处理的叶片、茎秆和籽粒锌含量的平均值则分别显著提高 224.6%、78.5% 和 12.1%。4) 在土壤施锌条件下,不同锌肥品种中氮锌复合肥 (S3) 和钾锌复合肥 (S5) 的增产效果显著高于磷锌复合肥 (S4),而在叶面喷锌条件下,以 Kali-EPSO-Zn 处理 (F6) 提高水稻各器官锌含量的能力显著高于 ADOB-IDHA-Zn 处理 (F7) 和 ZnSO₄·7H₂O 处理 (F3)。5) 较常规稻种 (CK-grain),应用富锌稻种 (Zn-grain) 育苗种植的水稻产量和籽粒锌含量分别提高 4.6% 和 3.9%。 【结论】 结合锌肥土施增加水稻产量和喷施增加籽粒锌含量的田间应用效果,因地制宜地综合采用土施氮锌复合肥和喷施钾锌复合肥的配合施肥方法以及选用富锌稻种育苗种植,可协同实现最佳的锌肥利用效率、最大程度地稳产增产和提高稻米的锌营养品质。      

配施中微量元素对宁夏酿酒葡萄产量及品质的影响

中微量元素的缺乏是限制贺兰山东麓酿酒葡萄品质的重要因素。通过大田试验研究了在常规施肥的基础上配施Fe、Mn、Cu、Zn、B、Mo、Mg、Ca等元素对贺兰山东麓酿酒葡萄赤珠霞(Cabernet Sauvignon)生长及品质的影响。结果表明:配施B元素显著提高葡萄百粒重,降低可滴定酸的含量;Fe和Mn元素显著降低葡萄百粒重、果粒粒径及可溶性固形物的含量;Cu和Zn元素显著降低可溶性糖的含量,Zn元素显著提高单宁和总花色苷的含量,配施Ca和Mg可提高葡萄产量、可溶性固形物含量和糖酸比。单独配施一种微量元素的效益是有限的,将8种微量元素混合施肥可较常规施肥的百粒重提高32.5 g,总产量提高43.8%,同时显著提高还原糖和可溶性糖含量,降低可滴定酸含量,并具有较高的单宁、总花色苷和总酚含量。因此,该地区多种微量元素综合配施在提高葡萄产量和品质方面显著优于配施单种微量元素肥料。     

适宜施氮钾水平提高滴灌秋茶的产量及品质

2018年5月至10月在山东省日照市开展田间试验,研究滴灌条件下不同施氮(纯N)水平(0 kg/hm~2,N0;45 kg/hm~2,N1;75 kg/hm~2,N2;105 kg/hm~2,N3)和施钾(K2O)水平(0 kg/hm~2,K0;27 kg/hm~2,K1;54 kg/hm~2,K2;81 kg/hm~2,K3)对秋季茶叶产量及品质的影响。结果表明:在不同氮水平的对比中,施氮量为75 kg/hm~2(N2K2)时取得最高鲜叶产量及茶多酚、儿茶素、水浸出物含量;施氮量105 kg/hm~2(N3K2)时氨基酸、咖啡碱含量高于其他处理,且酚氨比最小。在不同钾水平的对比中,施钾量81 kg/hm~2(N2K3)时取得最高鲜叶产量且叶绿素、咖啡碱含量最高;施钾量54 kg/hm~2(N2K2)时氨基酸、茶多酚、儿茶素、水浸出物含量最高;施钾量为27 kg/hm~2(N2K1)时酚氨比最小。综合分析所有施肥处理的产量与品质,施氮量105 kg/hm~2、施钾量54 kg/hm~2(N3K2)时表现最优。     

不同品种粳稻的锌强化方法研究

通过比较不同锌肥施用方式对不同粳稻品种产量以及稻米锌含量的影响,筛选高效锌水稻品种和最佳锌施用方式。在田间试验条件下,分析9个粳稻品种的稻米产量和锌含量对S(锌肥土施)、SB(锌肥土施结合孕穗期喷施)、SF(锌肥土施结合扬花期喷施)和SBF(锌肥土施结合孕穗期和扬花期喷施)4种锌肥施用方式的响应,结果表明,各水稻品种稻米的锌含量在18.1～29.3 mg·kg~(-1)之间,吉洋1号、吉农大809、吉粳302、吉宏6号、长粳717和稻花香2号为高锌品种,吉农大899为中锌品种,平粳8号和吉粳515为低锌品种。锌肥土施对大多数水稻品种无显著增产作用,不同品种的稻米锌含量在施用锌肥后平均增幅为18.0%;S、SB、SF和SBF处理的稻米锌含量分别较不施锌处理提高了8.3%、17.4%、19.5%和27.0%,但3个喷施处理间的平均锌含量无显著差异。锌肥土施结合叶面喷施能显著提高稻米中的锌含量,不同施用方式的施锌效果因品种而异。选择富锌高产品种,锌肥土施结合适当生育期叶面喷施,可实现增产和稻米锌强化,实现水稻高产优质种植。     

施氮量对食用向日葵产量及品质的影响

为明确氮肥用量对向日葵产量和品质的影响,合理施用氮肥,在内蒙古中西部3个试验点开展了向日葵不同氮肥用量试验研究。研究结果表明:(1)施用氮肥均有显著的增产效果,各个试验区施氮肥的产量反应均为:200 kg/hm~2150 kg/hm~2100 kg/hm~2300 kg/hm~2,推荐施氮量(200 kg/hm~2)的增产率为24.6%。氮肥用量与向日葵产量呈抛物线相关,施氮量为189.7～194.0 kg/hm~2时可获得向日葵最高产量,经济最佳施氮量应为148.5～157.4kg/hm~2。(2)百粒重、花盘直径和株高与向日葵产量达到显著相关。(3)随着植株生长发育,氮素逐渐向籽粒中转移,植株各器官氮素浓度依次为:籽实空盘叶茎;氮素吸收量:籽实茎空盘叶,施氮量为200 kg/hm~2的吸收量最高。(4)随着施氮量增加肥料利用率降低,在经济最佳施氮量150 kg/hm~2的情况下,内蒙古中西部氮肥的利用率平均为34.7%,氮肥的农学效率为5.38 kg/kg,每生产100 kg向日葵籽实吸收氮素为4.57 kg。(5)施氮量与向日葵籽实的蛋白质含量呈正相关关系,与籽实粗脂肪含量呈负相关关系。在经济最佳施氮量的情况下,籽实粗蛋白质产量和籽实粗脂肪产量均较高。从综合产量与氮素吸收量、经济效益来看,在内蒙古中西部氮素最佳投入量以150 kg/hm~2为宜。     

锌源和施锌方法对石灰性土壤锌组分及锌肥利用率的影响

【目的】选用合适的锌肥以及合理的施肥方式不仅可以提高小麦籽粒锌营养品质,还可以提高石灰性土壤的锌肥利用率。因此,研究不同锌源和施肥方式对石灰性土壤中锌组分含量以及锌肥利用率的影响具有重要意义。【方法】采用盆栽试验,设置两种锌源(水溶态锌肥Zn SO4·7H2O和螯合态锌肥Zn-EDTA)全层混匀均施和表面条施两种方式,调查了土壤中交换态Zn(Ex-Zn)、松结有机态Zn(LOM-Zn)、碳酸盐结合态Zn(Carb-Zn)、氧化锰结合态Zn(Ox Mn-Zn)、紧结有机态Zn(TOM-Zn)5种形态锌的含量,分析了小麦对锌肥的利用率。【结果】全层混匀均施与表面条施,两种锌肥均增加了小麦籽粒和秸秆Zn含量,全层均施Zn SO4·7H2O处理的籽粒Zn含量比对照提高43%,均施和表面条施Zn-EDTA的籽粒Zn含量分别比对照提高57%和75%;Zn-EDTA均施和条施的锌肥利用率分别为6.5%和5.3%,Zn SO4·7H2O均施和条施的锌肥利用率分别为3.6%和1.3%。小麦收获后,条施Zn SO4·7H2O和Zn-EDTA的施锌区有效锌含量分别为9.25和1.97 mg/kg,分别为均施处理的2倍和1.8倍;与对照相比,Zn SO4·7H2O和Zn-EDTA条施及均施的4个处理均增加了土壤中各形态锌的含量,并且4个处理与对照土壤中各形态Zn含量的规律一致,即:松结有机态碳酸盐结合态紧结有机态氧化锰结合态交换态。均施Zn SO4·7H2O和Zn-EDTA 2个处理的交换态Zn含量分别为0.12和0.13 mg/kg,条施分别为0.38和0.54 mg/kg;均施处理松结有机态Zn含量分别为5.26和1.56 mg/kg;不同处理碳酸盐结合态Zn含量变化趋势与松结有机态Zn含量基本一致;条施Zn SO4·7H2O施肥区氧化锰结合态Zn含量为对照的4倍,不同处理的土壤中紧结有机态Zn含量变化规律与氧化锰结合态Zn含量变化规律相似。相关分析表明,土壤交换态Zn、松结有机态Zn和碳酸盐结合态Zn含量均与有效锌含量呈显著正相关关系,与不施锌肥相比,Zn-EDTA施入土壤后,小麦收获后松结有机态Zn和碳酸盐结合态Zn含量明显增加,而紧结有机态Zn则相对减少。【结论】潜在缺锌石灰性土壤上施用螯合态锌肥Zn-EDTA能显著增加土壤中潜在有效的锌组分以及锌肥利用率,而且施用螯合态锌肥后,较高的有效锌含量可以维持至小麦收获后,有效提高了锌肥利用率。与均施处理相比,条施这种集中施用的施肥方法可以增加近根系土壤中有效性较高的锌形态含量。     

Soil zinc and pH effects on leaf zinc and the interaction of leaf calcium and zinc on zinc toxicity of peanuts

Abstract

Zinc toxicity of peanuts (Arachis hypogaea L.), resulting from excessive amounts of Zn applied to previous crops, has been observed for many years in a limited number of peanut fields in Georgia. A tentative critical value of 12 mg/kg of Mehlich No.1 extractable soil Zn has been reported, but soil pH should be considered in establishing a more precise critical value since availability of soil Zn is affected greatly by soil acidity. A 3‐year study was conducted on a Tifton loamy sand (thermic, Plinthic Paleudults) to evaluate the relationship between soil pH and soil Zn on concentration of Zn in peanut leaves. Factorial treatments were 0, residual, medium, and high rates of Zn and soil pH levels near 5.5, 5.9, 6.2, and 6.8. Pod yields were not affected by treatments and Zn toxicity was not observed. Leaf Zn was affected more by soil pH than by soil Zn, but correlation coefficients were highest where both soil pH and soil Zn were included in the determination. A regression equation, based on soil pH and soil Zn, showed that an increase in soil Zn from 1.0 to 10.0 mg/kg increased leaf Zn 202 mg/kg at soil pH 4.6 and only 9 mg/kg at pH 6.6. Data from growers’ fields, in which samples were collected from eight healthy and toxic areas, indicated that a leaf Ca:Zn ratio of 50 or less was required for Zn toxicity of peanuts rather than high concentrations of leaf Zn per se.     

Comparison of soil zinc extractants for detection of applied zinc and prediction of leaf zinc concentration

Abstract

Many soil extractants have been developed for determination of zinc (Zn) availability to plants. The optimum soil Zn extractant should be useful not only for prediction of plant Zn concentration but also for detection of applied Zn levels. The objectives of this study were: i) to compare soil Zn extradants for detecting applied Zn and for predicting peanut leaf Zn over a range of soil pH levels, and ii) to correlate other soil‐extractable Zn levels with Mehlich‐1. Soil and peanut leaf samples were taken from a field study testing pH levels as the main plots and Zn application rates in the sub‐plots. Extractable Zn was determined on soil samples using Mehlich‐1, Mehlich‐3, DTPA, MgNO₃, and many dilute salt extradants of varied strength and pH. Correlation of extractable soil Zn to cumulative applied Zn levels revealed Mehlich‐1, Mehlich‐3, DTPA, and AlCl₃ extradants to be among the best indicators of applied Zn. Leaf Zn concentration was best correlated with soil Zn extracted by dilute salts, such as KCl, CaCl₂, NH₄Cl, CaSO₄, and MgCl₂. Including soil pH as an independent variable in the regression to predict leaf Zn considerably improved R‐square values. The DTPA‐extractable soil Zn levels were very well correlated with Mehlich‐1‐extractable Zn. Mehlich‐3 extracted about 20% more soil Zn than Mehlich‐1, but Mehlich‐3 soil Zn was not as well correlated to Mehlich‐1 soil Zn as DTPA soil Zn. Lower pH solutions extracted more of the applied Zn, but more neutral solutions extracted Zn amounts which were better correlated with Zn uptake. On the other hand, Mehlich‐1, which had a lower pH, had better correlations with both applied Zn and leaf Zn than did Mehlich‐3. Shortening the DTPA extraction time to 30 minutes resulted in better correlations than the standard two hour extraction time. Chloride (Cl) was the best anion tested in relation to soil applied Zn recovery in combination with potassium (K), calcium (Ca), and aluminum (Al), and Cl optimized leaf Zn correlations for ammonium (NH₄), K, Ca, and magnesium (Mg). The larger the valence of the cation, the better the correlation with applied Zn and the poorer the correlation with leaf Zn.     

Effects of zinc complexes on the distribution of zinc in calcareous soil and zinc uptake by maize

The movement and availability of Zn from six organic Zn sources in a Typic Xerorthent (calcareous) soil were compared by incubation, column assay, and in a greenhouse study with maize (Zea mays L.). Zinc soil behavior was studied by sequential, diethylenetriaminepentaacetate, and Mehlich-3 extractions. In the incubation experiment, the differences in Zn concentration observed in the water soluble plus exchangeable fraction strongly correlated with Zn uptake by plants in the greenhouse experiment. Zinc applied to the surface of soil columns scarcely moved into deeper layers except for Zn-ethylenediaminetetraacetate (EDTA) that showed the greatest distribution of labile Zn throughout the soil and the highest proportion of leaching of the applied Zn. In the upper part of the column, changes in the chemical forms of all treatments occurred and an increase in organically complexed and amorphous Fe oxide-bound fractions was detected. However, the water soluble plus exchangeable fraction was not detected. The same results were obtained at the end of the greenhouse experiment. Significant increases were found in plant dry matter yield and Zn concentration as compared with the control treatment without Zn addition. Increasing Zn rate in the soil increased dry matter yield in all cases but Zn concentration in the plant increased only with Zn-EDTA and Zn-ethylenediaminedi-o-hydroxyphenyl-acetate (EDDHA) fertilizers. Higher Zn concentration in plants (50.9 mg kg(-)(1)) occurred when 20 mg Zn kg(-)(1) was added to the soil as Zn-EDTA. The relative effectiveness of the different Zn carriers in increasing Zn uptake was in the order: Zn-EDTA > Zn-EDDHA > Zn-heptagluconate >/= Zn-phenolate approximately Zn-polyflavonoid approximately Zn-lignosulfonate.     

玉米幼苗对短暂供锌的反应及缺锌后再供锌的恢复

用溶液培养的方法研究了玉米幼苗对短暂供锌的反应及缺锌后再供锌的恢复效果.结果表明:10～12小时的正常供锌后再缺锌培养,对玉米幼苗的危害比一直缺锌的还大;缺锌培养使玉米幼苗出现缺锌症状后再正常供锌,可使之恢复,低锌使玉米出现的缺锌症状比缺锌培养的更难以恢复,证明低锌比缺锌对玉米造成的危害更大,缺锌使玉米的有机酸分泌增加,低锌增加的更多.     

锌对不同基因型玉米缺锌后的恢复效果及胚乳在缺锌中的作用

用溶液培养法研究不同Zn浓度对玉米缺Zn后恢复效果及胚乳在缺Zn中作用结果表明,不同基因型玉米缺Zn后恢复所需的适宜Zn浓度不同,敏感品种比非敏感品种要求更高的Zn浓度。缺Zn后恢复所需适宜Zn浓度高于正常培养所需适宜Zn浓度,低浓度Zn(0.1μmol/L)无恢复作用(生物量)。带上胚乳使敏感品种在缺Zn、低Zn下受抑程度(缺Zn与供Zn生物量差值)提高,而非敏感品种受抑程度反而减小。缺Zn与低Zn培养时体内P含量提高,胚乳可缓解这种影响。缺Zn后再供Zn可使体内Zn含量提高,而P含量降低,玉米对Zn产生奢侈吸收,使体内Zn含量超过正常供Zn水平,表明缺Zn后植物对Zn的要求提高。0.1μmol/L Zn恢复对“吉单120”玉米Zn含量无明显影响,但“辽单22”玉米Zn含量显著提高,这表明非敏感品种比敏感品种利用低Zn的能力更强。     

不同白菜品种对锌的响应及锌利用效率研究

采用盆栽试验研究了白菜[Brassica campestris L.ssp.Chinensis(L.)Makino]4个品种对不同浓度锌(Zn 0、1、10 mg/kg)的响应.结果表明,白菜的生物量及体内锌含量随锌水平的增加而增加;但白菜品种对锌营养反应的敏感性不同.地上部锌含量、锌积累量和锌吸收效率均以日本华冠(J...     

Effect of vesicular-arbuscular mycorrhizae and zinc application on dry matter and zinc uptake of greengram (Vigna radiata L. Wilczek)

Summary In a greenhouse study we examined the effects of vesicular-arbuscular mycorrhizae (VAM) inoculation, using Glomus macrocarpum and of Zn application on dry matter production and Zn uptake by greengram in two mollisols. The VAM inoculation significantly increased the dry weight of different plant parts and the Zn uptake in both soils. Inoculated plants showed a greater response to the application of Zn at 2.5 and 5.0 mg kg^-1 soil in a Zn deficient clay loam soil. The inoculated plants also absorbed — more water than the uninoculated plants. Mass flow and diffusion were the principal processes by which Zn reached the plant roots; mass flow was particularly important in the absence of VAM in a sandy soil fertilized with higher Zn doses (5 and 10 mg kg^-1 soil). The greater supply of Zn to inoculated roots was attributed to an apparent diffusion process rather than to mass flow of Zn.     

Soil zinc and pH effects on zinc concentrations of corn plants

Abstract

Z1nc (Zn) deficiency of corn (Zea mays L.) has been detected in 20 or more states 1n the United States including Georgia. Since soil pH is a major factor in assessing the availability of soil Zn, this measurement has been included with acid extractable soil Zn in developing calibration Zn soil tests in North Carolina and Virginia. The objectives of this study were to develop a reliable soil test for Zn based on soil pH and Mehlich 1 soil Zn for corn gown on coarse‐textured soils and to compare our soil test values with those recently published from North Carolina where Mehlich 3 was the extractant. The study was conducted 1n 1979 to 1981 on a Tifton loamy sand (Plinthic Paleudult) site which had been used to study the influence of lime rates on micronutrient availability since 1970. Treatments consisted of four soil pH levels ranging from 5.3 to 6.6 and soil Zn levels ranging from 0.5 to 4.9 mg/kg. The Zn levels were established from the previous study where 5.6 kg Zn/ha had been applied annually for eight years (residual treatment) and by applying 3.36 or 6.72 kg Zn/ha during 1979, 1980 and 1981.

Soil Zn, corn shoot, and ear leaf Zn values were reflective of the amount of Zn applied except that the residual Zn treatment resulted in Zn concentrations > than the annual application of 3.36 kg Zn/ha. Zinc tended to accumulate in the soil and in corn leaf tissue more from the residual Zn than the recently applied Zn treatments, especially at the highest pH levels. Increasingly more soil Zn was required to increase corn shoot and ear leaf Zn one mg/kg as soil pH increased. In the initial year, each unit (kg/ha) of applied Zn increased corn shoot Zn approximately 4 units (mg/kg) at pH 5.3 and only 0.3 unit at pH 6.6. Zinc deficiency symptoms developed in corn shoots for the two highest soil pH levels in two of three years. Corn yields were increased by Zn only in 1980 and were increased by residual or applied Zn at pH levels of 6.2 and 6.6. Regression equations from these studies were utilized to develop predictive corn shoot and ear leaf Zn values over wide ranges in soil Zn and pH. Our field research data using Mehlich 1 extractant could possibly be used satisfactorily in North Carolina regression equations where Mehlich 3 was the extractant; however, certain limitations would need to be imposed in the North Carolina equations.     

Effects of chelated zinc,soluble and coated fertilizers,on soil zinc status and zinc nutrition of maize

Abstract

Maize (Zea mays L.) was greenhouse cultivated with doses of 5, 10, and 15 ppm of zinc (Zn) in order to test the effectiveness of laboratory‐prepared coated and uncoated Zn fertilizers with commercial Zn‐EDTA and Zn‐ligno‐sulphonate (LS). Large increases were achieved both in crop yield and in Zn uptake in all cases while a large part of the Zn applied remained in the soil in easily plant‐available forms. Positive significant correlations were obtained between available Zn and the first three sequentially extracted fractions (water soluble plus exchangeable, organically complexed and that associated to amorphous sesquioxides) and also between the variables, yield, Zn concentration, and plant Zn uptake. Zinc uptake by the maize plants can be fairly accurately predicted from its sequential fractioning in the soil using an equation obtained by multiple regression analysis. Consideration of the amounts of Zn remaining as available (DTPA extractable) in the soil and results of a plant analysis let us conclude that under the conditions of our tests, Zn‐EDTA is a better Zn source than Zn‐LS. In addition, coating of Zn‐EDTA products with rosin improves their performance.