Carbon storage by urban tree cultivars, in roots and above-ground

Urban trees can favorably affect factors underlying global warming by storing carbon and by reducing energy needs for cooling and heating buildings. To estimate carbon stored in roots and above-ground portions of trees, data was collected consisting of whole tree sampling of Amelanchier, Malus, Pyrus, and Syringa cultivars. Roots were excavated using an Air-Spade^™. Regression analysis resulted in two equations for predicting total carbon storage based on height and diameter of trees up to 20 cm dbh: Y = 0.05836 (dbh²) for root carbon storage, and Y = 0.0305 (dbh² × h)^0.9499 for above-ground carbon storage, explaining 97% and 96% of the variation, respectively. Average carbon stored in roots of various cultivars ranged from 0.3 to 1.0 kg for smaller trees, those 3.8 to 6.4 cm dbh, to more than 10.4 kg for trees 14.0 cm to 19.7 cm dbh. Average total carbon stored by cultivars ranged from 1.7 to 3.6 kg for trees less than 6.4 cm dbh to 54.5 kg for trees larger than 14.0 cm. The data from these equations apply mainly to trees in nurseries and recently transplanted trees. Comparisons showed that above-ground estimates from previous studies using a sampling technique overestimated values obtained from actual above-ground weights.     

不同供磷水平对柱花草和黑籽雀稗根际生理活性的影响

以热带柱花草和黑籽雀稗为材料，通过盆栽试验，研究不同磷水平对其根际酸性磷酸酶、微生物数量及根系活力的影响。结果表明：2种牧草根际酸性磷酸酶(ACP)活性随着磷浓度的增加而降低，在低磷(P0)处理时达最高，柱花草的ACP活性为603.24 mg/(kg·h)，黑籽雀稗为367.21 mg/(kg·h)。当高磷浓度处理时，柱花草根际ACP活性较黑籽雀稗低。各处理中，柱花草的根际微生物总量较黑籽雀稗高，柱花草根际真菌的数量随磷浓度的增加而减少，处理间差异达极显著水平，低磷处理时土壤真菌数量较多，这有利于根瘤菌的形成。2种牧草的根系活力随着施磷浓度的增加而递减。黑籽雀稗根系活力P0处理极显著高于P3和P4处理,显著高于P2处理。黑籽雀稗根系活力受供磷水平的影响大于柱花草。     

五笔字根“形、音、义”三结合速记法——兼谈英文字母键位速记

根据汉字＂形、音、义＂的三个特点,采用字根与字母组合构图以及谐音组词的方式助记五笔字根,以使每个五笔字根都能与相应键位的英文字母建立直观、形象、易于联想的紧密联系,从而达到事半功倍、快速持久的记忆效果。     

退化高寒草甸斑块根—土复合体特征研究

高寒草甸斑块的根-土复合体对局部水土流失过程具有调控作用,为研究其特征及抗侵蚀效应,本研究选取三江源区达日县境内典型中度退化草甸的植被斑块为研究对象,调查草甸斑块中心与边缘植物群落特征,测定斑块边缘0～10 cm土层和斑块中心0～20 cm土层的容重、含水率、毛管孔隙度等土壤物理性质,并开展单根拉伸和根-土复合体直剪试验。结果表明：受优势种矮嵩草的分布影响,地上生物量主要分布在斑块中心,根系主要分布在0～10 cm土层;斑块中心区域土壤抗剪强度、内摩擦角和粘聚力均随土层深度的增加而减小;斑块边缘区域土壤粘聚力,抗剪强度明显高于斑块中心区域,草甸斑块植物根系是土壤抗剪强度的主要影响因素。草甸斑块根-土复合体能明显增加退化草甸土壤的抗侵蚀能力,研究结果可为深入研究高寒草甸根系固土功能及水土流失调控提供科学依据。     

不同供磷水平小麦苗期根系特征与其相对产量的关系

研究了缺磷条件下不同基因型小麦苗期根系形态学及生理学适应特征 ,结果表明 :在缺磷环境中 ,小麦根轴数量和侧根长度明显减小 ,同化物向根部的分配比例增加 ,根轴长度、侧根数量和根系长度等均是显著提高。供试基因型小麦的根轴数量及其长度的差异在每个供磷水平及不同供磷水平之间均是显著的 ,说明这两种性状的差异是由基因型和环境因素共同决定的 ;而侧根特征的差异只在不同供磷水平之间是显著的 ,表明侧根性状主要是受环境因素控制的。对 6种基因型小麦的研究表明 ,高磷水平的小麦种子根的生长角度明显低于低磷处理的小麦 ,根角之间存在着显著的基因型差异。在缺磷条件下 ,6种基因型小麦完整根系分泌的酸性磷酸酶活性、根轴数量、根轴长度、根生长角度和根系长度之间均存在着显著的基因型差异。相关分析表明 ,缺磷条件下的小麦苗期根系形态指标和根系分泌的酸性磷酸酶活性的交互作用与小麦的相对产量之间具有显著的线性关系 ,这种关系说明以上 5种性状均可作为早期有效地筛选磷高效小麦品种的指标     

Methods and Techniques to Enhance the Production of Secondary Metabolites in Hairy Roots

Hairy roots culture is a new means to gain the plant secondary metabolites. How to enhance the production of secondary metabolites in hairy roots becomes a new hotspot recently. The authors summarize recent trends and results about the increase of the production of secondary metabolites in medicinal plant hairy roots. The change of culture conditions and the application of biotechnologies can enhance the production of secondary metabolites in hairy roots.     

基于EIT的土壤中油菜根茎检测

主要应用EIT技术检测土壤中油菜的根茎。搭建16电极数据采集系统,采用相邻法激励测量模式获得成像数据并应用基于MatLab的MNR算法进行图像重建。结果表明:本实验方法能实现油菜根茎的无损检测,可以检测出油菜根茎的位置和大小信息;对干枯的油菜根茎检测效果比新鲜根茎差,而对于腐烂的根茎,不能检测出来。据此,可以对土壤中油菜根茎进行可视化观察,了解其根系生长情况。     

非充分灌溉条件下水稻根系生长发育特征研究

以广西桂林站水稻非充分灌溉试验的实测资料为基础，分析比较了不同稻田水分条件下水稻根系的形态、类型、根系数量及分布特点，同时，对非充分灌溉条件下水稻根系的生长发育特征及其对产量影响的机理进行了初步研究。其结果对指导有效、省水的稻田灌溉具有重要意义。     

地下滴灌系统施加氟乐灵的排根效应研究

通过小麦盆栽试验,研究向地下滴灌系统施加氟乐灵的排根效应。结果表明,地下滴灌不施药时滴头所在的竖直方向根密度较大,而施加少量氟乐灵后,滴头所在位置处根密度有不同程度降低,说明氟乐灵有抑制小麦根系向滴头附近生长的趋势。施药时间、施药浓度和施药量均对药物排根效应显著影响,其中施药时间为极显著。施药时间越晚,排根范围越小,出苗后50d施药的平均排根范围仅为3.03cm2;施药浓度越小,排根范围越小,浓度为1.5g/L及1.2g/L的排根范围接近,而浓度为0.9g/L的平均排根范围最小,为6.0cm2;施药量越小排根范围越小,施药量为0.023g/滴头的平均排根范围为8.37cm2。     

Calcium nutrition of the sugarbeet

Abstract

When sugarbeet seedlings are transferred from a complete nutrient solution to one from which Ca has been withheld, the rootlets and tops fail to develop. The same transfer at the eight‐leaf stage causes the rootlets to become stubby and swollen at the tips and blade expansion becomes modified; particularly the upper portions of the blades attaining nearly full development, which pucker and often develop a cupping or hooding effect; a unique symptom characteristic of Ca deficiency. As each new leaf develops, the blade area becomes smaller until only a black tip remains at the apex of the petiole, which is the symptom referred to as tip‐burn for this petiole and the successively . shorter petioles formed as Ca deficiency increases in severity. Strangely, these symptoms also appear during periods of rapid growth when the nutrient solution contains as much as 10 to 28 milliequivalents per liter of Ca or when soils are high in Ca. This implies that Ca absorption and possibly translocation limits the Ca supply at the growing point. Increasing Mg in the nutrient solution decreases Ca uptake and increases Ca deficiency. Potassium deficiency, unexpectedly, induces Ca deficiency apparently by decreasing the translocation of Ca to the growing point.

These phenomena suggest the hypothesis that when ion absorption takes place from the root exchange site that has the affinity for H > Ca > Mg > K > Na, then the H generated internally replaces, and the roots absorb, Na, K and Mg preferentially. Externally, Ca would be adsorbed preferentially from the nutrient solution by the exchange complex, and with the addition of Mg, it would compete for the common adsorption site of Ca and limit Ca absorption internally. Under these conditions potassium‐deficient nutrient solutions would not induce Ca deficiency by decreasing Ca absorption but rather by decreasing Ca translocation. Theoretically, Ba would replace H more readily than Ca on the exchange complex, and therefore, Ba would be adsorbed preferentially and Ca uptake would increase. This effect of Ba was verified experimentally.

Since the translocation of ⁴⁵Ca to the growing point was found to be unrestricted under Ca‐sufficient and Ca‐deficient conditions and since the formation of insoluble Ca compounds such as phosphate or oxalate did not account for the Ca deficiency at the growing point, the cause of the Ca deficiency at the growing point is most likely the higher priority of the storage root for Ca over tops when leaf blades and storage root are both expanding rapidly. However, Ca retransport from older to younger parts of the sugarbeet plant may be restricted by the formation of Ca phosphate under Ca‐deficient conditions and Ca oxalate under Ca‐sufficient conditions.

Calcium deficiency increases net photosynthesis per unit blade area initially, probably because of blade puckering, but not on a per unit chlorophyll basis.