不同Mg肥种类对烤烟产量、质量、产值的影响

 不同种类的Mg肥对烤烟产量、外观质量影响不显著。但是仍有一定的增产、增值效果。磷酸铵镁对增加烟叶含Mg率、改善吸食品质有较好效果,其次是硫酸镁和氯化镁,蛇纹石肥效缓慢。不施用Mg肥烟叶产、质量都是最差的。     

供Mg水平对烤烟累积N、K、Ca、Mg的影响

盆栽试验表明 :(1 )供 Mg促进烟株对 NO- 3-N的吸收和积累 ;(2 )供 Mg极显著提高烟叶中 Mg的含量 ,但也显著降低 K和 Ca的含量 ;(3 ) Mg与 K、Ca之间存在着拮抗作用 ;(4 )供 Mg提高烟叶的 K/(Ca+Mg)值 ,改善卷烟燃烧品质 .缺Mg,K/(Ca+Mg)比值较低 ,品质不良     

Influence of temperature on nutrient concentration and tetany potential of hardinggrass and tall fescue

Grass tetany (Hypomagnesemia) potential of TAM Wintergreen Hardinggrass and 16 tall fescue lines and varieties was estimated by determining the K, Ca and Mg concentrations in the herbage and the ratio of K/(Ca + Mg) (milliequivalent basis). Data were obtained at four dates during a two‐year period to determine the environmental conditions under which selections should be made to achieve the greatest progress in decreasing the tetany potential of tall fescue and to determine if either of the grasses have high tetany potential in the North Texas area. Hardinggrass had a greater potential to produce grass tetany than tall fescue when grown on the Northern Blackland Prairie of Texas. There were significant differences in K, Ca and Mg concentrations and K/(Ca + Mg) ratio among dates and tall fescue lines. The average temperature for the 30 days before harvest was related to the mineral content and to the K/(Ca + Mg) ratio in all varieties. The K(Ca + Mg) ratio was highest at approximately 18°C but the Mg content fell below the 0.18% required for lactating beef cows when the average temperature for the 30 days before harvest was 22.4°C. Progress could be made in breeding for low grass tetany proneness but selections should be made over a wide range of temperatures considering both the Mg content and ratio of K/(Ca + Mg).     

Effect of magnesium fertilization on yield and leaf composition of tomato plants

Tomato plants were grown for 2 years at 4 different rates of Mg fertilization on a Princeton loamy sand at pH 4.8 with 29 kg exchangeable Mg/ha. Calcareous limestone was used to provide a pH treatment in the second year. Magnesium deficiency symptoms were observed on plants grown on plots having ≤ 38 kg/ha NH₄OAC‐extractable Mg. Application of 56 kg Mg/ha corrected Mg deficiency and produced a significant increase in yield. Application of calcitic limestone also produced significant yield increases, but did not affect the development of Mg deficiency symptoms. Tomato yield was increased 27.9% by Mg application and 17.7% by lime application. Highest tomato yield was obtained with application of 112 kg Mg/ha. Symptoms of Mg deficiency were observed when the Mg concentration in recently mature leaf tissue was in the 0.30 to 0.32% range. Magnesium concentration in leaf tissue increased linearly with increasing Mg rate. Leaf Mg concentration at various growth stages of the tomato plant was variable depending on Mg treatment. Magnesium fertilization rate bad little effect on Ca or K leaf concentrations. Application of Calcltic limestone increased leaf tissue Ca and reduced leaf tissue Mg and Mn concentrations.     

Effect of planting date and growth stage on secondary and micronutrient content of soybean tissue

Field experiments were conducted to determine the effect of planting date and cultivar on B, Zn, Mn, Fe, Mg, and Ca content of soybean leaflets, petioles, and stems at beginning bloom (R1), beginning seed (R5) and physiological maturity (R7) growth stages. The concentrations of all the nutrients analyzed were influenced by planting date and cultivar in at least one year. The concentration ranges were: B, 16–167 ppm; Zn, 14–98 ppm; Fe, trace‐575 ppm; Mn, 12–122 ppm; Mg, 0.18–0.89%, and Ca, 0.47–3.02%. As the plants developed, [Fe] generally decreased, [Mn] increased, and [Zn] showed no consistent response. Changes in B, Mg, and Ca concentrations with plant development varied with the plant part. Leaflet [Ca] and [B], and petiole [Ca] and [Mg] increased during seedfill. Petiole and stem [B], and stem [Mg] and [Ca] decreased during seedfill.     

Influence of thigmic stress or chlormequat chloride on tomato morphology and elemental uptake

Root dry weight and leaf number were not affected by thigmic stress or chlormequat chloride. Shoot dry weight, shoot:root dry weight ratio, shoot height, leaf area, and root surface area were decreased by both thigmic stress and chlormequat chloride. However, root length was decreased and root radius increased only by chlormequat chloride. Total element uptake was decreased by both thigmic stress and chlormequat chloride. In the shoot and root, N was not affected, P was increased in the shoots, K decreased in the shoots but increased in the roots, and Mg decreased in the roots as a result of thigmic stress and chlormequat chloride. Whereas, Ca was decreased in the roots and Mg increased in the shoots by chlormequat chloride. The uptake of N, P, Ca, or Mg was not affected by thigmic stress or chlormequat chloride, however, K uptake per root surface area decreased. Thigmic stress decreased K in both the upper and lower stem but did not affect leaf concentration of K. However, chlormequat chloride decreased K in both the stem and leaves. Thigmic stress because of the role of K in cell elongation. Chemical name used: (2‐chloroethyl)trimethyl‐ammonium chloride (chlormequat chloride).     

东北细辛根系对钙、镁、硫的积累动态研究

对不同年生、不同生育时期的东北细辛根系中钙、镁、硫的积累动态进行了研究。结果表明:五年生东北细辛根系中钙的积累量变幅较大,5月末展叶期最高(22.15 mg/kg),到7月初果实采收后下降到最低(8.98 mg/kg);二年生植株根系中不同时期钙的积累均高于三,四,六年生,镁的积累较活跃,6月末果期达到最高(10.28 mg/kg);五年生镁的积累量在7月初降到最低(5.06 mg/kg);不同年生东北细辛根系对硫的积累量为209.3~60.92 mg/kg,远高于对钙、镁的积累量;从5月初展叶到6月中旬开始结果五年生植株根系硫的积累量高于其它年生,二年生最低。东北细辛根系对钙、镁、硫的积累以二、五年生较为活跃,且表现在开花期到结果期。     

过量Mg2+对农作物种子萌发特性的影响

以MgCl2溶液考察Mg^2＋对玉米、大豆种子的萌发及生长的影响,为进一步研究镁粉尘的污染机理、生物响应和污染等级划分提供依据。     

中国春小麦GBSS与淀粉颗粒结合特性的研究

以小麦品种中国春(Triticum aestivum)为材料,分析了颗粒结合淀粉合成酶（GBSS）与淀粉颗粒结合的影响因素及作用力。通过SDS-PAGE及测定GBSS溶液浓度,证实小麦GBSS与淀粉粒结合的紧密程度受温度影响,在50~80℃范围内,GBSS从淀粉颗粒上的解离量随温度的升高逐渐升高;而在85~95℃之间,解离量随温度的升高而降低;沸水浴处理15 min的GBSS解离量较大,但超过35 min时GBSS的量反而有所减少。Mg²⁺浓度也影响GBSS的解离,低于1.75 mmol L^-1时,随Mg²⁺浓度降低解离量逐渐升高;高于2.5 mmol L^-1时,随Mg²⁺浓度的升高解离量逐渐降低。表明GBSS与淀粉粒的结合力是非共价键。     

拔节水对春玉米钙镁及微量营养元素吸收动态模型及分布运转的影响

本项研究查明拔节水使春玉米体内Ca,Mg及Fe,Mn,Cu,Zn浓度有不同程度的降低,而吸收累积量却显著增加;对相对吸收量最多的时期没有改变,但改变了吸收动态模型参数,最快吸收速率(mg/d.株)分别为Ca39.05,Mg14.22,Fe.0.784,Mn0.121,Cu0.068,Zn0.285,均有不同程度的增加;成熟期运转率分别为Ca19%,Mg45%,Fe19%,Mn10%,Cu26%,Zn49%,大多有所增加;对百公斤籽粒吸收量、养分生产效率影响很小或没有影响,绝大多数元素的消耗系数有所增加.