钾与钙·硼混合喷施对龙眼果实品质及耐贮性的影响

在果园土壤低硼条件下,以储良龙眼为试材,作了连续两年研究.结果表明,在龙眼假种皮发育期间,树冠分别喷施0.3%KH2PO4、0.3%KH2P04+1%CaCl2、0.3%KH2PO4+0.2%H3803溶液3次,可显著增大成熟龙眼果型、提高果实组织鲜重,增加果实的可食率、果肉可溶性固形物和糖含量,并促进果实组织对Ca、B的吸收积累,显著提高果实组织K含量;在30±2℃条件下贮藏,三处理均降低了贮藏期间果实失重率、提高好果率,减缓了果肉营养成分含量的下降.可见钾与钙、硼混合喷施对于提高龙眼果实的品质与耐贮性和维持贮藏过程中果实品质有一定作用.     

钾肥对糯玉米籽粒建成及品质形成的影响

以鲜食型糯玉米香白糯为材料,采用小区试验研究了钾肥对秋播鲜食糯籽粒建成及品质形成的影响。结果表明:施用钾肥可使鲜食糯玉米籽粒的鲜重、干重、体积分别提高0.158g/(100粒·d)、0.136g/(100粒·d)、0.130cm3/(100粒·d)速度生长,而籽粒含水率以高于对照0.22个百分点速度脱水。钾肥可明显提高鲜食糯玉米籽粒的赖氨酸、粗蛋白、游离氨基酸、可溶性蛋白、脂肪及淀粉含量。钾肥区籽粒的赖氨酸、粗蛋白含量均在授粉14d出现峰值后缓慢下降;籽粒的游离氨基酸、可溶性蛋白含量在授粉后14d出现峰值后迅速下降,至授粉后22d,下降速度放慢;籽粒的脂肪、淀粉含量在授粉10d后即呈上升趋势,至授粉后22d,上升趋势放慢。秋播鲜食糯玉米适宜采收期以授粉后22~26d为宜。     

钾营养对杂交稻光合作用动态及产量形成的效应

 用杂交稻威优35号在低钾土壤上进行盆栽试验，设置三个钾水平：K0(不施钾)；K1(1．5 g K/ 15 kg土)；K2(3．0 g K／15 kg土)。结果表明：(1) K0处理叶片发育过程中净光合率降低而暗呼吸增高，叶绿体发育迟缓而解体较早，光合功能期缩短；K1及K2的净光合率明显高于K0，光合功能期亦较长，而暗呼吸则长时期保持较低水平。(2)K0处理在灌浆期净光合作用有明显的“午休”现象， 而K1、K2则在夏日中午仍保持较稳定的净光合率。(3) K0处理“午休”的出现与蒸腾速率增高有关，且在上午9时还有一蒸腾高峰，使叶子大量失水；施钾处理在一天中的蒸腾曲线则较平稳。(4)K0处理稻株叶片中含K量从上到下有明显梯度，灌浆期下层叶的含K量仅为剑叶的30．08％，易引起早衰，且使根系生长受到严重影响；施K处理叶片从上到下无明显梯度。总之，施K增加光合面积，避免早衰，增加粒数，显著提高谷粒产量。     

强筋冬小麦品种藁8901的优化施肥技术

通过对氮、磷、钾三因素旋转回归设计，以小麦产量和品质性状为目标，对强筋冬小麦品种藁8901的优化施肥技术方案进行了研究。结果表明，氮、磷、钾三因素对藁8901的产量和品质指标的影响各不相同。对产量和品质指标的作用大小顺序依次为氮〉磷〉钾，氮肥是影响该品种产量和品质指标的首要因素。通过藁8901产量和品质指标与氮、磷、钾三因素关系的回归方程进行多目标综合决策，模拟筛选出多个优化施肥量厦配合方案。入选方案的施肥量范围为N239．25～300kg／hm^2，P2O5 150～300kg／hm^2，K2O 112．5～225kg／hm^2。     

土壤类型对土壤钾素与烤烟烟叶钾素分布及其相互关系的影响研究——以云南省曲靖市为例

以云南曲靖烟区5种不同土壤类型土样及其对应的烟样为材料,分析了土壤钾素和烤烟烟叶钾素含量在不同土壤类型中的分布特点及其相互关系。结果表明:(1)土壤钾素含量与烤烟烟叶钾素含量在5种土壤类型中存在显著差异,不同土壤类型中平均全钾含量高低顺序为紫色土黄壤水稻土新积土红壤;速效钾含量高低顺序为:黄壤新积土水稻土紫色土红壤;平均烤烟钾含量在不同土壤类型中的分布高低顺序为:黄壤新积土红壤水稻土紫色土。(2)烟叶钾素仅在红壤类型上与土壤全钾含量呈极显著正相关,仅在红壤、新积土和紫色土类型上与土壤速效钾呈极显著正相关,在其他土壤类型下烟叶钾素与土壤钾素相关性不明显。在将土壤钾素含量分组后,在红壤中,烟叶钾含量随土壤全钾和速效钾含量的变化而表现出了较大的差异;在黄壤和水稻土中,烟叶钾含量在不同土壤钾素分组间未表现出明显的差异性;在新积土和水稻土中,烟叶钾含量在土壤全钾含量分组中没有明显的差异性,但在土壤速效钾含量的分组中则表现出较大的差异性。     

钾素水平对油菜酶活性的影响

利用盆栽试验研究不同钾素施用水平对油菜薹期酶活性的影响。结果表明 ,钾素缺乏和过量均可导致油菜叶片POD含量上升 ,CAT和SOD含量下降。不同施钾水平条件下 ,油菜下部叶的酶活性差异比上部叶更明显     

Puccinellia tenuiflora Exhibits Stronger Selectivity for K+ over Na+ than Wheat

Abstract

The characteristics of selectivity for K⁺ over Na⁺ by the roots of the halophyte Puccinellia tenuiflora were investigated in comparison with the glycophyte wheat (Triticum aestivum). Under various NaCl concentrations, the concentrations of K⁺ in the shoots of P. tenuiflora were 16–24% lower than those of wheat, whereas the concentrations of K⁺ in Puccinellia roots were 2.8–4.0 times higher than those of wheat. In 200 mM NaCl, the concentrations of Na⁺ in shoots of P. tenuiflora and wheat were similar under high K⁺ levels, but the concentrations of Na⁺ in wheat were 1.6 times higher than those in Puccinellia under low K⁺ levels. The concentrations of K⁺ in roots of P. tenuiflora were 1.5–2.0 times higher than those of wheat under low K⁺ levels. Formulas are given for calculating net selective absorption (SA) capacity and selective transport (ST) capacity by roots for K⁺ over Na⁺. We interpret SA as the net capacity of selectively absorbing K⁺ over Na⁺ by epidermal and cortical cells of whole plant roots into the root symplast. ST could reflect the net capacity of selection for K⁺ over Na⁺ transport from whole root stelar symplast to the xylem vessels. The lower ST value of P. tenuiflora might be the reason for accumulation of K⁺ in its roots. The SA values of P. tenuiflora and wheat were approximately equivalent in the low-affinity K⁺ uptake range. The SA values of the former were about two times higher than that of the latter in the high-affinity K⁺ uptake range, showing the root high-affinity K⁺ uptake system of the halophyte P. tenuiflora has a stronger capacity for K⁺ uptake.     

Blocking effects of extracellular Cd2+ on the inward rectifier potassium channel

AIM:To study the blocking effects of extracellular Cd²⁺ on the inward rectifier potassium channel (IRK1) expressed in the Xenopus oocytes. METHODS:Two-microelectrode voltage clamp (TEV) method was used. RESULTS:Cd²⁺ can concentration-, time- and voltage dependently block IRK1 instantaneous currents ( 1.5 ms after voltage applied ) when external Cd²⁺ concentration is 0, 0.1, 0.15, 0.3, 0.9, 2.7 or 5.4 mmol/L with K⁺ concentration fixed to 90 mmol/L. Cd²⁺ almost has no effect on the gating property and outward currents of IRK1. Cd²⁺ can concentration-dependently increase the normalized conductance of IRK1. IRK1 can not permeate Cd²⁺ because reverse potential did not change. Three exponential fitting analyze indicates that time constant is not changed with the change in Cd²⁺ concentration. This shows that the inhibitory effects of Cd²⁺ may be caused by surface potential or the blocking site of Cd²⁺ is at the surface of the channel. Because external Cd²⁺ can not inhibit IRK1 macroscopic currents more powerfully when external Cd²⁺ concentration is lower. These mean that external Cd²⁺ does not work through surface potential mechanism.CONCLUSION:Cd²⁺ is considered as one of the fast open channel blockers of IRK1 and its blocking site is at the surface of the channel.     

烟草中钾含量测定的两种预处理方法相关性的研究

[目的]对来自全国各地烟草基地的100个烟草样品进行钾含量的测定,建立水提取和酸消解2种预处理方式的转换模型,考察2种方法的相关性。[方法]分别采用水提取和酸消解2种方式对样品进行预处理,然后用火焰原子吸收测定,对2种方法的试验参数进行优化,并对2种预处理方式的测定结果进行回归分析。[结果]建立了2种方式之间的线性转换方程,同时对常规酸消解和水提取转换值进行了t检验,结果 t为0.286 0,小于t0.05,44(t0.05,44=2.021)。[结论]常规酸消解测定值与水提取转换值无显著差异,可以用水提取代替酸消解来对烟草样品进行预处理,使测定方法简化、环保。     

离子色谱法测定再造烟叶中的钠·氨·钾·镁·钙

[目的]建立离子色谱法测定再造烟叶中的钠、氨、钾、镁、钙的含量。[方法]采用0.05 mol/L盐酸溶液作为提取溶液,在超声波辅助条件下提取30 min,离子色谱法准确快速地同时检测出再造烟叶中的钠、氨、钾、镁、钙5种阳离子的含量。[结果]该方法对于钠、氨、钾、镁、钙5种阳离子的检出限和定量限分别为0.01和0.05μg/ml,0.06和0.019μg/ml,0.03和0.012μg/ml,0.04和0.013μg/ml,0.15和0.048μg/ml,5种阳离子3个浓度梯度的加标回收率范围均在91.7%~109.9%。用建立的方法对市场上常用的几种再造烟叶进行了测定显示,低含量的氨离子和钠离子含量的偏差分别为51.17%和51.96%,而高含量的镁、钾和钙离子含量偏差均在20%以内。[结论]该研究建立的方法具有操作简便、准确度高、重复性好、适用性强等优点,适用于大批量样品分析。