长期施肥对潮土硫、钙和镁组分与平衡的影响

本文以在潮土进行的 2 0年的长期肥料试验为例进行研究 .结果显示 ,单施化肥处理土壤有效硫出现耗竭趋势 ,而施用有机肥的处理则保持较高有效硫水平和由于所含钙磷肥和有机肥以及灌溉水中含有数量可观的钙 ,土壤水溶态钙和交换态钙含量除对照外 ,各处理间十分接近 ,各处理的钙均有赢余 ;由于有机肥对土壤镁素的补充作用 ,水溶态镁、交换态镁、酸溶态镁和全镁含量均表现为原始土 >单施有机肥 >对照 >化肥与有机肥配施 >单施化肥 ,即使在施用有机肥条件下 ,土壤镁素仍然亏缺     

麻沙泥田增施钙镁肥对烤烟生长和产量的影响

通过田间试验研究麻沙泥田上钙镁肥对烤烟生长和产量的影响。结果表明:在施钙肥条件下,施镁15 kg/hm2的产量最高,高达2709 kg/hm2,比不施镁肥处理增产3.6%。足量施入镁肥或镁肥与钙肥混施具有提高烟苗株高和叶片数,促进其生长的效果,烟叶产量和烤烟等级均表现为随施镁量的增加先增加后降低的趋势。适量施入镁肥具有提高烤烟产量、上等烟叶比例、上中等烟叶比例和产值的作用。施镁可提高烤烟叶片中镁含量,钙肥对镁的吸收具有显著的抑制作用。不施钙时,施入镁肥显著提高烤烟中钾、镁含量,而施入钙肥会对钾镁养分的吸收起到抑制作用,施钙条件下增加镁的施入可大幅度提高烟叶的钾、镁养分含量。在土壤中不施钙肥条件下,施入镁肥对钙的吸收会起副作用,而在施入大量钙肥情况下,施入适量镁肥显著提高烟叶的钙含量。     

甘蔗光合速率的日变化及其对光温的响应

在田间和盆栽正常生长条件下,Ｃ４植物甘蔗的光合速率日变化明显地不同于Ｃ３植物甘薯．甘薯为典型的双峰曲线,中午Ｐｎ的明显降低主要是由非气孔因素限制引起;而甘蔗为单峰曲线,其峰值出现在上午１０００左右．甘蔗Ｐｎ变化受到光温条件的强烈影响,强光有利于Ｐｎ提高,弱光下其Ｐｎ略低于甘薯,温度过高（＞４０℃）或过低（＜１５℃）明显地抑制甘蔗光合作用．还分析了引起Ｐｎ变化的气孔和非气孔限制．     

高产冬小麦钙,镁元素吸收积累与分配规律的研究

在高产栽培条件下,选用不同类型（大,中和多穗型）品种定点重复３ａ研究了冬小麦植株对Ｃａ,Ｍｇ的吸收积累动态和成熟期的最终分配,并对Ｃａ,Ｍｇ的吸收积累和分配特点进行了比较。结果表明,植株对Ｃａ,Ｍｇ的吸收强度最高值均出现在拔节－挑旗阶段,且该阶段的吸收比例和每１００ｋｇ生物产量的Ｃａ,Ｍｇ吸收量也最高;各类品种在不同年份间的吸收动态基本一致,成熟期１００ｋｇ子粒产量需吸收Ｃａ,Ｍｇ量分别为７９９．     

Landscape characteristics of <Emphasis Type="Italic">Rhizophora mangle</Emphasis> forests and propagule deposition in coastal environments of Florida (USA)

Field dispersal studies are seldom conducted at regional scales even though reliable information on mid-range dispersal distance is essential for models of colonization. The purpose of this study was to examine the potential distance of dispersal of Rhizophora mangle propagules by comparing deposition density with landscape characteristics of mangrove forests. Propagule density was estimated at various distances to mangrove sources (R. mangle) on beaches in southwestern Florida in both high-and low-energy environments, either facing open gulf waters vs. sheltered, respectively. Remote sensing and Geographic Information Systems were used to identify source forests and to determine their landscape characteristics (forest size and distance to deposition area) for the regression analyses. Our results indicated that increasing density of propagules stranded on beaches was related negatively to the distance of the deposition sites from the nearest stands of R. mangle and that deposition was greatly diminished 2 km or more from the source. Measures of fragmentation such as the area of the R. mangle forests were related to propagule deposition but only in low-energy environments. Our results suggest that geographic models involving the colonization of coastal mangrove systems should include dispersal dynamics at mid-range scales, i.e., for our purposes here, beyond the local scale of the forest and up to 5 km distant. Studies of mangrove propagule deposition at various spatial scales are key to understanding regeneration limitations in natural gaps and restoration areas. Therefore, our study of mid-range propagule dispersal has broad application to plant ecology, restoration, and modeling.     

红壤土花生施用镁肥的效应

红壤土花生施用镁肥对营养器官的生长发育及单株总果数等都没有明显的影响 ,但能显著或极显著地增加单株饱果数和百果重 ,从而使花生的产量能显著或极显著地提高 ,是一项简便易行、成本低、经济效益较好、前景诱人的增产措施     

叶面喷施硫酸钾镁肥对不同部位烟叶镁、钾、钙吸收的影响

[目的]在云南省曲靖市植烟土壤交换性钙镁比超过20的缺镁烟区,通过土壤镁肥施用和叶面喷施进行钙镁比调控,了解其对烤烟钾、钙、镁吸收的影响,为曲靖市缺镁烟区烤烟的平衡施肥技术提供理论依据和生产指导。[方法]通过田间小区试验,采用完全随机区组设计,以不施镁肥作为对照,分别设3个叶面喷施硫酸钾镁肥处理和2个根层施镁＋叶面喷施处理。采集根、茎、上部叶、中部叶和下部叶5个部位进行烘干称重,并且粉碎制样,测定钾、钙、镁含量;每个小区从初烤烟叶中选取上部（B2F）、中部（C3F）、下部（X2F）样品,分析烟叶全钾、钙、镁含量。[结果]从不同部位来看,叶面喷施及土壤施用和叶面喷施配合调控钙镁比提高了中、下部烟叶对镁、钾的吸收以及下部烟叶对钙的吸收,但降低了上部烟叶对镁、钾、钙的吸收以及中部烟叶对钙的吸收。烟叶不同部位镁、钾、钙的累积分配量比较表现为中部叶〉下部叶〉上部叶;从不同部位来看,中、上部烟叶钙镁比、钾镁比降低,下部烟叶钙镁比增加,而下部烟叶钾镁比处理之间没有差异。[结论]叶面喷施及土壤施用和叶面喷施配合调控对烟叶钙镁比、钾镁比的影响,主要是通过影响镁的吸收。     

浅山地区大白菜应用硫酸钾镁肥肥效试验研究初报

在浅山地区进行了大白菜施用硫酸钾镁肥试验,试验结果表明:硫酸钾镁肥对大白菜的生育期和农艺性状影响不太明显,但有显著的增产作用,产量比对照增产10%以上,增产效果明显。     

Feeding Magnesium Supplement to Foals Reduces Osteochondrosis Prevalence

The influence of supplements containing magnesium on the etiology of osteochondrosis (OC) is unknown. We did two studies to measure the effect of additional minerals (especially magnesium) on OC. In study 1 (five studs, in total 64 mares and foals aged 0 to 5 months, equally divided into two groups), supplementation with minerals and placebo was used. Blood samples were taken from foals at age of 2, 8, and 16 weeks. At the same time, milk samples were taken from the mare. Bone biomarkers (osteocalcin and C-terminal telopeptide [CTx] of type I [CTx-1] collagen) and minerals (calcium, phosphorus, and magnesium) were measured in blood and the same minerals in milk of the mare. At the end of the study, the femoropatellar (knee), tarsocrural (hock), and metacarpophalangeal and/or metatarsophalangeal (fetlock) were radiographed and scored for the presence and grade of osteochondrotic lesions. In study 2 (six studs, 54 foals aged 5 to 12 months, equally divided into two groups), the same was repeated. At the start and end of the study, again blood samples were taken and analyzed on the same parameters as in study 1. Also, the same radiography was done. In study 1 in the mineral supplemented group, 21.9% were diagnosed with osteochondrosis compared with 41.9% in the placebo group. In study 2, there was no change in OC between 5 and 12 months in the placebo group whereas there was a drop of 14.3% in incidence in the supplement group. We concluded that magnesium supplementation reduced OC prevalence.     

乳化剂与内水相镁盐浓度对油包水乳液稳定性的影响

研究并讨论了内水相镁盐与疏水乳化剂PGPR对油包水(W/O)乳液稳定性的影响。制备W/O乳液的油水质量比为3∶2,油相中疏水乳化剂聚甘油蓖麻醇酸酯(PGPR)质量分数为0.5%~2.0%,水相中Mg Cl2·6H2O的质量分数为0~12.0%。采用Turbiscan Lab Expert稳定性分析仪分析了W/O乳液贮藏14 d过程中的整体稳定性。结果表明:在14 d贮藏过程中,液滴的聚沉和沉淀会导致乳液失稳。提高疏水乳化剂PGPR和镁盐的浓度可提高W/O乳液的稳定性。对W/O乳液的粒径分布及油水两相界面特性进行分析,发现W/O乳液稳定的机制在于乳液粒径的减小以及油水界面张力的降低。此外,油水两相界面粘弹性也在一定程度上改善了乳液稳定性,油水界面膜粘弹性随着镁盐浓度的增加呈现先上升后下降的趋势。