不同细毛山药品种矿质元素含量的研究

为了探明细毛山药不同品种在矿质营养成分方面的特性,收集了当地主栽的5个细毛山药品种进行了试验。结果表明,细毛山药矿质元素含量具有品种间差异性。不同品种之间干物质含量有着显著差异,以TG品种最高,NT品种最低。试验对5个品种的矿物质含量进行了分析,发现在试验的所有品种内,矿物质含量的变化趋势都表现为:钾>镁>钙>钠>铁>铝>锌>铜>锰>镍>铬>铅>钴;但在不同品种间,各个元素含量有明显差异,其中大量元素钾、镁的含量在品种间有显著差异;在微量元素中,铁、锰、铬的含量也在品种间有显著性差异;其他所测量的各种矿质元素在品种间没有显著性差异。同时,还测量了砷、硒、镉3种元素,可能由于含量太低而没有检出。对1~3年不同种龄的山药产品进行了元素分析,发现其元素含量趋势与上述一致,但没有发现种龄对山药矿质元素含量有显著影响。     

不结球白菜品质性状与矿质营养的典型相关及逐步回归分析

选用42个不同生态型的不结球白菜品种,研究3叶片粗纤维、Vc、可溶性糖、有机酸、氨基酸、综合风味等品质性状与N,P,K,Ca,Mg,S等矿质营养元素之间的关系,旨在探讨不结球白菜品质性状与育种中利用一些简单易测的矿质元素来筛选品质指标,并通过施肥措施提高其品质的可行性。典型相关和双重筛选逐步回归分析表明:不结球白菜叶片N,K,S与品质性状的相关性均达到显著或极显著水平。品质性状与矿质元素的相关主要由品质性状的粗纤维,Vc,NO3-和矿质营养性状中的N,K,S,Mn的相关引起。N,K对品质性状起着直接的正向效应,氮的正向作用有一定的适度范围,而钾起着绝对品质元素的作用,硫对综合风味的负效应最强,可能与硫含量的高低影响风味物质的合成有关。     

氮对水培生菜营养液元素动态变化及产量与品质的影响

氮素是生菜最重要的营养元素之一,影响生菜的产量和品质,通过动态监测水培生菜生长及营养液矿质元素变化过程,为水培生菜合理有效的营养液管理提供理论依据。采用深水培方法,在5个氮素浓度9,8,6,4,3 mmol/L条件下对生菜产量、品质及营养液元素动态变化过程进行了试验观测,分析了氮对水培生菜生长、矿质元素利用效率及动态吸收量的影响。不同氮素处理生菜的干物质积累量随时间差异越来越显著,在氮素水平为6 mmol/L时生菜可获得最大产量;硝酸盐含量随氮水平的增高先增高后稍有降低,氮素浓度为8 mmol/L时最高;Vc和可溶性蛋白不断增高,在氮素浓度为9 mmol/L时含量最高;可溶性糖先增高后减小,氮素浓度为6 mmol/L时含量最高;不同氮素浓度显著地影响了生菜对氮的吸收,高浓度氮素水平有利于生菜对氮、磷的吸收,较低氮素水平则有利于生菜对钾、钙、镁的吸收。生菜对氮、磷的吸收主要集中在定植后的20~30 d,平均吸收量分别占到全生育期的64.81%和61.88%,对钾的吸收在定植后30~40 d较多,平均吸收量占到全生育期的44.46%,生菜对钙、镁的吸收在定植后都较均匀。生菜对磷、钾、钙、镁的利用效率呈现出先增大后减少的趋势,对氮的利用效率线性减小。当氮素水平为8 mmol/L时,生菜全生育期对矿质元素的吸收量最大,为582.31 mg/株,此时生菜获得较好的产量和品质,较高的磷、钾、钙、镁利用效率,但是氮的利用效率较低。     

Dynamic change of mineral nutrient content in different plant organs during the grain filling stage in maize grown under contrasting nitrogen supply

The introduction of new hybrids and integrated crop-soil management has been causing maize grain yield to increase. However, less attention has been paid on the nutrient concentration of the grain; this aspect is of great importance to supplying calories and nutrients in the diets of both humans and animals worldwide. Increasing the retranslocation of nutrients from vegetative organs to grain can effectively increase the nutrient concentration of grain and general nutrient use efficiency. The present study involved monitoring the dynamic change of macro- and micronutrients in different organs of maize during the grain filling stage. In addition, the mobility of different elements and their contribution to grain nutrient content were evaluated in a 2-year experiment under low (LN, no N supplied) and high N (HN, 180 kg N ha⁻¹) supply. Under HN supply, the net remobilization efficiency (RE) of the vegetative organs as a whole (calculated as nutrient remobilization amount divided by nutrient content at silking) of N, P, K, Mn, and Zn were 44%, 60%, 13%, 15%, and 25%, respectively. The other nutrients (Mg, Ca, Fe, Cu, and B) showed a net accumulation in the vegetative organs as a whole during the grain filling stage. Among the different organs, N, P, and Zn were remobilized more from the leaves (RE of 44%, 51% and 43%, respectively) and the stalks (including leaf sheaths and tassels) (RE of 48%, 71% and 43%, respectively). K was mainly remobilized from the leaves with RE of 51%. Mg, Ca, Fe, Mn, and Cu were mostly remobilized from the stalks with the RE of 23%, 9%, 10%, 42%, and 28%, respectively. However, most of the remobilized Mg, Ca, Fe, Mn, Cu, and Zn were translocated to the husk and cob, which seemingly served as the buffer sink for these nutrients. The REs of all the nutrients except for P, K, and Zn were vulnerable to variations in conditions annually and were reduced when the grain yield and harvest index were lower in 2014 compared with 2013. Under LN stress, the RE was reduced in P and Zn in 2013, increased in Cu and unchanged in other nutrients. The concentration of these nutrients in the grain was either unchanged (P, K, Ca, Zn, and B) or decreased (N, Mg, Fe, Mn, and Cu). It is concluded that grain N, P, K, Mn, and Zn, but not Mg, Ca, Fe, Cu, and B concentration, can be improved by increasing their remobilization from vegetative organs. However, enhancing the senescence of maize plant via LN stress seems unable to increase grain mineral nutrient concentration. Genetic improvement aiming to increase nutrient remobilization should take into account the organ-specific remobilization pattern of the target nutrient.     

Ameliorative effects of inoculation with the plant growth-promoting rhizobacterium Pseudomonas sp. DW1 on growth of eggplant (Solanum melongena L.) seedlings under salt stress

The objective of this work was to evaluate the effect of inoculation with the plant growth-promoting rhizobacterium Pseudomonas sp. DW1 on eggplant (Solanum melongena L.) growth, mineral uptake and activities of the antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) of plant leaves under salinity stress. The study was conducted in pot experiments using eggplant (S. melongena L., cv. Yinjia) and a coastal soil. The NaCl concentration of the coastal soil was 0.57 g (kg soil)⁻¹. Four NaCl levels were tested: 0.57, 1.0, 2.0, and 3.0 g NaCl (kg soil)⁻¹, by adding NaCl to soil, respectively. Pseudomonas-inoculated seeds had an increase in the germination percentage over its non-inoculated seeds under salinity. Salinity negatively affected growth of eggplant; however, plants inoculated with Pseudomonas sp. DW1 grew to a significantly greater extent than plants that were not treated with this bacterium. Salinity significantly decreased K⁺ concentration, increased Na⁺ concentration, and did not significantly decrease Ca²⁺ content in shoots of eggplants. Inoculating with Pseudomonas sp. DW1 increased shoot Ca²⁺ of eggplant compared to the non-inoculating eggplant plants under salinity. Inoculating treatments with Pseudomonas sp. DW1 had no effect on shoot Na⁺ concentration in 0.57 and 1 g (kg soil)⁻¹ NaCl, but there were significant decreases in inoculated treatments than in non-inoculated ones at 2 and 3 g (kg soil)⁻¹ NaCl. Salinity decreased SOD activities and increased POD activities, and inoculated Pseudomonas sp. DW1 had an increase effect on SOD activity in the leaves of eggplants. Alteration of mineral uptake and increase in the antioxidant enzyme activities may be two mechanisms for the alleviation of salt stress. Based on the results of the experiment reported herein, the use of the plant growth-promoting rhizobacterium treatment may provide a means of facilitating plant growth under salt stress.     

A comparative evaluation of the Mississippi soil test method for determining available manganese,magnesium, and calcium

Abstract

Soil Samples (72) were collected from the Delta, Hill, and Northeast Blackland areas of Mississippi. Chemical analyses for manganese, magnesium, and calcium were made using the Mississippi Soil Test Solution (MSTS) and several other extracting solutions chosen for comparison. For the determination of available soil manganese, the MSTS proved to be as effective as either the Double Acid (0.025 N HCl in 0.05 N H₂SO₄) or 0.1 N H₃PO₄. The acid extractants removed more manganese than 1 N NH₄OAc (pH 7.0) and therefore included forms that are not exchangeable. The methods studied for magnesium determinations were equilibrium extraction with 1 N NH₄OAc, MSTS, Double Acid, 0.25 N CaCl₂, and leaching with 1 N NH₄OAc. All methods were highly correlated and therefore would be equally effective in determining available soil magnesium. Since MSTS and equilibrium extraction with 1 N NH₄OAc removed similar amounts of magnesium from the soil, the same calibration can be used. Calcium determinations were made using equilibrium extraction with 1 N NH₄OAc, MSTS, and Double Acid, and by leaching with 1 N NH₄OAc. All methods proved effective in measuring available soil calcium on acid soils.     

亚热带花岗岩地区土壤矿物风化过程中盐基离子的释放特征

矿物风化过程中盐基离子释放遵从一定的化学计量关系,这种化学计量关系一般只能通过模拟实验来获取。本研究采用pH 7.0的EDTA-乙酸铵溶液将土壤中的交换性盐基离子完全洗脱出来,然后用Batch方法模拟不同pH溶液淋溶洗脱盐基和未洗脱盐基土壤,旨在消除土壤中交换性盐基离子的影响后更为准确地判断土壤矿物风化的盐基离子释放特征。结果表明:未洗脱盐基土壤的淋出液pH由3.73±0.14逐渐上升到4.23±0.06,主要原因是淋溶液中有高浓度的NH_4~+;洗脱盐基土壤矿物风化后淋出液pH从7.39±0.02逐渐下降到5.39±0.17,主要是由于土壤中可风化矿物减少。土壤交换性盐基离子会改变盐基离子释放特征、释放总量:未洗脱盐基土壤经酸雨淋溶后,各盐基离子释放均呈现急速下降后逐渐平缓的趋势,洗脱盐基土壤矿物风化后,K~+及盐基离子释放总量呈波动上升趋势,且盐基离子释放总量比未洗脱盐基土壤低。土壤交换性盐基离子的存在还会改变淋出液中的盐基离子化学计量关系:未洗脱盐基土壤的K~+︰Ca~(2+)︰Mg~(2+)︰Na+化学计量关系为11︰13︰4︰1(当量比),而洗脱盐基土壤为7︰2︰2︰1。K~+是盐基离子中风化释放量最多的,大部分K~+来自于土壤中云母的风化。因此,只有利用洗脱盐基土壤的盐基离子释放量才能准确计算矿物风化速率并获得准确的化学计量关系。土壤矿物风化作用随着淋溶液酸度增大而增强,但模拟一年降雨量的情况下,p H 3.5、4.5和5.5三种不同p H溶液对矿物风化后盐基离子的释放在实验期间没有显著性影响,较长时间后的差异性有待观察。本研究表明,可以通过预洗脱盐基土壤然后模拟酸雨淋溶的方法,观察矿物风化特征,特别是盐基离子释放的化学计量特征。     

Fruit Quality at Harvest of “Jonathan” Apple Treated with Foliarly-Applied Calcium Chloride

Abstract

The response of “Jonathan” apple trees (Malus domestica, Borkh.) grafted on EMLA 111 to frequent application of calcium chloride (CaCl₂) was studied at Topeka, Emporia, and Conway Springs, Kansas, orchards in 2002. Trees were sprayed one to eight times with foliar applications of calcium chloride at the rate of 8.971 kg ha^?1. First spray was made when fruits were 1.4, 0.9, and 1.6 cm diameter at Topeka, Emporia, and Conway Springs, respectively. More than six applications of CaCl₂ improved fruit quality at harvest. Improvement included an increase in fruit weight, size, appearance, skin redness, and reduction of scald incidents. Although CaCl₂ applications had no effect on percent of soluble solids, the ratio of soluble solid content to titratable acidity was increased by frequent CaCl₂ application. Fruit skin redness was the most improved quality of “Jonathan” apple as the result of CaCl₂ applications. No symptoms of fruit russetting or leaf scalding resulting from frequent CaCl₂ application were observed. Increase in fruit quality was attributed to a linear increase in Ca concentrations in fruit and leaf tissues. Increase in Ca concentrations in fruit and leaf tissues of treated trees coincided with increases in potassium (K), magnesium (Mg), phosphorus (P), and nitrogen (N) concentrations compared with untreated control trees. Potassium, Mg, P, and N were correlated with fruit quality as much as, or in some cases more than, Ca. This information suggests that changes in mineral balance with CaCl₂ applications contributed to improvement of fruit quality and is evidence that frequent Ca application improved “Jonathan” apple quality in Kansas.     

Effects of five additive materials on mechanical and dimensional properties of wood cement-bonded boards

There is a growing desire to improve the properties and use of nonwood plant materials as supplements to wood materials for wood cement-bonded boards (WCBs). This study was conducted to determine the comparative properties of WCBs containing various amounts of discontinuous inorganic fiber materials, such as alkali-resistant glass fiber, normal glass fiber, mineral wool, and nonwood plant materials such as retted flax straw and wheat straw particles. Tested cement-bonded boards were made at wood/additive compositions of 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 (weight percentages). Seventy-eight laboratory-scale WCBs were produced. Various board properties, such as the modulus of rupture (MOR), internal bonding strength (IB), water absorption (WA), thickness swelling (TS), and linear expansion (LE), were studied. The test results showed that three types of discontinuous inorganic fiber used as reinforcing materials in composites significantly enhanced and modified the performance of WCBs. The mechanical properties and dimensional stability of cement-bonded board were significantly improved with increasing amounts of the additives. MOR and IB were increased; and WA, TS, and LE of boards were reduced by combination with the inorganic fiber materials. The results also indicated that combination with retted flax straw particles only slightly increased the MOR of boards, and wheat straw particles led to marked decreases in all the mechanical properties and the dimensional stability of WCBs.Part of this report was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000     

稀土对刺槐苗木生理特性影响的研究

稀土对刺槐苗木生理特性影响的研究赵兰勇，梁玉堂（山东农业大学林学院泰安２７１０１８）王九龄（北京林业大学北京１０００８３）关键词稀土，刺槐，光合速率，叶绿素含量，水分利用效率，矿质元素含量近年来，稀土元素在农业上的应用研究越来越受到人们的重视，并且已...