打顶时不同追钾对云南烤烟含钾量的影响

田间试验研究打顶时不同追K对云南烤烟含K量的影响结果表明 ,打顶时追施K肥可提高烤烟叶片含K量和烟株吸K量。烤烟田间土壤补施K肥 (包括根部集中施用K2 SO4、KNO3 和缓效钾 )处理其提高烟叶含K量效应明显优于叶面喷施K肥 (包括叶面喷施KH2 PO4、KNO3 和K2 SO4)处理 ,而 3种土壤追施K肥处理以施K2 SO4和KNO3 效果最佳 ,烤烟生育后期追施K肥提高中、上部叶片含K量效果最佳 ,顶叶含K量由对照的 2 .6 %增至3.2 %。     

河西走廊稻区土壤K素动态及K肥施用效果

通过6年的试验示范，对河西走廊中部的张掖市稻区土壤K素动态变化，进行了长期定位踊跃测试。结果表明，该区各类土壤速效钾含量均呈下降趋势，且下降程度因土壤类型、N、P、Zn肥及有机肥施用量等不同而异。同时，设多点对K肥施用量和效果进行了长期试验，从而找出了最佳施用量，为肥料结构的调整、合理施用K肥提供了科学依据。     

钾、硼和萘乙酸对烟株生长及钾吸收分配影响的研究

本文通过盆栽试验,研究了钾(K)、硼(B)和萘乙酸(NAA)对烟株生长和K吸收分配的影响。研究表明,在高K营养下,B、NAA及B NAA显著增加了烟株地上部干重和株高,但低K时影响不显著:B、NAA及B NAA明显提高了烟叶的光合强度、硝酸还原酶的活性及过氧化物酶的活性,这为提高烟叶产量和品质奠定了基础。B.NAA及B NAA各处理明显增加了中、上部烟叶的含K量。低K营养时,各处理烟叶的含K量上部>中部>下部;但在高K营养下,各处理烟叶上、中、下部含K量相近,以高K营养下B NAA处理的烟叶含K量最高。初步表明增施K肥时,喷施B和NAA可以提高烟叶的K含量。     

铵对不同作物根系钾高亲和转运系统的影响

为探讨植物苗期根系高亲和转运系统的K+吸收动力学特征及其是否受吸NH4+的影响,采用溶液培养和添加K+通道抑制剂的方法,对低K+浓度下5种植物在有铵和无铵时的K+吸收动力学特征进行了研究。结果表明,植物根细胞K+高亲和系统的吸钾特征曲线符合Michaelich-Menten方程。不同植物K+高亲和系统的Km值之间差异较小,均在50%以内,说明不同植物的载体与K+间的亲和性差异较小;不同植物K+高亲和系统的Vmax值间差异很大,说明不同植物根细胞膜上的K4+载体数量间差异很大,这是导致不同植物在低钾条件下吸钾能力差异较大的主要原因。铵的存在可以明显降低供试植物在低钾条件下对K+的吸收速率。与无NH4+情况比较,NH4+的存在可使大豆K+吸收的Vmax减少80%;但NH4+对不同载体与K+之间亲和性(Km的影响较小,由NH4+所导致的Km的降低率均在10%以内。可见,对高亲和系统而言,NH4+对K+吸收的影响主要是由于铵竞争细胞膜上的钾载体所造成的。     

生长后期不同断根及追钾对云南烤烟含钾量的影响

田间试验研究生长后期不同断根及追钾对云南烤烟含K量的影响结果表明 ,不同断根时间、断根部位和断根数量以及断根时追K与否及追施K素的形态等均对烤烟烟叶含K量的影响不同 ,烟株生长后期实施断根和追施K肥等措施可提高根系吸收活力和增加烟叶含K量。其中打顶时断根同时追施速效钾肥为最佳处理 ,其烟株各部位叶片含K量和上部叶片干物质量增幅最高 ,且易于实际操作。     

不同钾肥对虎奶菇菌核产量与氨基酸含量的影响

运用灰色系统理论,探讨了不同K肥相同含K量添加培养料栽培虎奶菇菌对产量与不同种类氨基酸总量的影响。结果表明,以硝酸钾为K肥对虎奶菇菌核产量与氨基酸含量影响的关联度最大,其次为氯化钾处理,硫酸钾处理关联度最小,这与栽培试验结果相一致。     

土壤控水条件下K、Ca配施对生菜品质的影响研究

试验设两个土壤含水量(土壤较高含水量和土壤中等含水量)条件下,采用二因素(K肥量、Ca肥量)二次回归正交旋转组合设计,9个处理,研究了在不同K、Ca配施条件下,生菜品质的变化。结果表明:在不同的土壤含水量条件下,K、Ca合量配施可以促进生菜营养品质的提高。     

对磷钾肥利用率和需用量计算探讨

P、K肥当季习惯利用率不考虑肥料与土壤养分的交换利用量,以无肥对照为基数,把利用率估算过低。原需肥量计算公式纯粹是利用率不妥计算的逆运算。应该从长期施肥效应考虑,残留P、K量也可交换利用及再利用。因此速效磷P、K肥平衡最佳需要量等于带出量除以总回收率。引用资料初步验证表明新算法成立,且很合理适用。     

不同酿酒葡萄品种钾素营养特点及其吸收与利用研究

采用水培和大田试验对“干红”、“干白”2个葡萄品种的K素营养特点及其吸收与利用的研究结果表明，2个葡萄品种干物质积累最大值时的介质浓度不同，“干红”葡萄品种的介质浓度(120μmol/L)高于“干白”葡萄品种(80μmol/L)，二者的生长速率、K素吸收效率、植株体内K浓度和根冠比均有显著差异。“干红”酿酒葡萄品种的土壤K素依存率低，为53.1%～80.3%，K肥利用率较高；而“干白”葡萄品种依存率为56.5%～82.1%，K肥利用率低。K素对植株鲜物质量、根长、根数、百粒重、结果枝率等均有明显影响，且可增加酿酒葡萄含糖量和出汁率。     

植物高效利用K素资源的研究进展

探讨了我国农业生产中Ｋ素资源的现状、提高植物对Ｋ肥利用效率的新途径、植物Ｋ营养特性差异的营养学基础和遗传学基础，为培育Ｋ肥利用效率高的耐低Ｋ作物新品种提供了理论基础。     

Determination of critical potassium concentration in young tomato plants using a nutrient interruption technique

Abstract

A new method suggested by Burns (1992) was used to estimate critical potassium (K) concentration in young tomato plants. A nutrient interruption experiment was conducted including only two treatments (+K and ‐K). Plants were successively harvested to measure yield and K concentration. This data was used to explore the relationship between the fraction of maximum growth rates and K concentration of plants suffering deficiency. The critical concentration was determined from this relationship. The new method provides a value for assessment of plant nutrient status which is well adjusted to the requirement of the plants with regard to maximisation of yield and has advantages compared to the widely applied method recommended by Ulrich and Hills (1990). Problems that arose were discussed and advantages and disadvantages of the new procedure were pointed out.     

Distribution of potassium fractions in sweet potato (Ipomoea batatas) garden soils in the Central Highlands of Papua New Guinea and management implications

Previous studies indicated that potassium (K) deficiency is an important soil‐related factor for yield decline of the sweet potato gardens in the Central Highlands of Papua New Guinea, where sweet potato is an important staple food crop. An effort was made to characterize various fractions of K in the diverse soils of this region under sweet potato, to ascertain the probable reasons behind the observed K deficiency and its relationship to decreasing yield trends. Soils from two depths (0–10 cm) and (10–20 cm) in two types of gardens (old and new gardens) were assessed for different fractions of soil potassium in volcanic and non‐volcanic soil groups. Volcanic soils (Hydrandepts and Andaquepts) were significantly lower (P < 0.05) in exchangeable K than the non‐volcanic soils (Dystropepts, Tropoqualfs and Eutropepts). Mean exchangeable K content of the non‐volcanic soils was 95.5 mg/kg, whereas that of volcanic soils was 72.4 mg/kg. Similarly, new gardens had an average exchangeable K content of 94.1 mg/kg, which was significantly greater than 71.6 mg/kg soil of older gardens. Non‐exchangeable K content differed significantly (P < 0.001) between the soil types; mean K content was 85.9 mg/kg for the volcanic soils, whereas in non‐volcanic soils, it was 184.9 mg/kg. Garden types also differed significantly (P < 0.05) with respect to non‐exchangeable K content; new gardens registering higher average values (by almost 20%) than the older gardens. Multiple regression analysis showed that variability in the tuber yield was as a result of variability of water soluble and exchangeable K (up to 22%), non‐exchangeable K (2%), mineral K (4%) and leaf K concentrations (10%). Older gardens, which are in volcanic soil groupings, are more susceptible to the K depletion problem because of continuous sweet potato cultivation, possibly owing to their lower K reserves. Such gardens should be managed either with sufficient fallow periods for regeneration of soil fertility or with suitable application of mineral K fertilizers to enhance productivity.     

Assessment of potassium in soils

Abstract

Potassium in soils from selected plots of the Broadbalk Experiment at Rothamsted, and Rotation I experiment at Saxmundham, U.K. was measured by five methods: the boiling nitric acid extractions of Haylock and Maclean, electro‐ultrafiltration, release to Ca‐saturated ion exchange resin, and a new procedure using extraction by HCl under reflux. All. the methods showed clearly the Gifferences between the two soil types, and between the differently fertilized plots on the basis of amounts, and 1n some cases rates of release, of different categories of soil K (exchangeable, fixed and native). The quantity of exchangeable K measured by each method, except that by Ca‐resin, gave significant correlations with the K balance of the soils, and yield and/or K offtake of winter wheat grown on the plots. The new HCl ‐reflux method gave the closest correlations. The amount and rate of release of fixed (available but not exchangeable) K estimated by HCl‐reflux was also correlated with yield and offtake.     

Calibration of the mehlich 3 soil test for potassium using leaf analyses and potassium deficiency symptoms in cotton plants

Abstract

A new calibration of the Mehlich 3 soil test for potassium (K) is proposed for the Mississippi Delta area, based on leaf analyses and K deficiency symptoms in cotton plants. The calibration reflects the need to supply adequate K concentrations to plants during the fruiting period of greatest K demand. The lowest levels and highest percent of sites exhibiting K‐deficiency symptoms were associated with the fifth week of flowering; or at the peak bloom stage of plant growth. The fifth week of flowering was selected to base soil and plant evaluations for K needs. A 1.5% leaf K level was selected as the critical leaf K level (the level that plants experience a nutrient deficiency and yield reductions), based on visual leaf K‐deficiency symptoms observed in plants 95% of the time. Leaf K concentrations below 1.51% identifies K‐deficiency symptoms in the upper leaves through eight weeks of flowering. A simplified equation [Topsoil K (lb/A) = 480 + 5 x CEC (Milliequivalents/100g soil)] defines critical soil test K concentrations with respect to the cation exchange capacity (CEC) in soils. This equation can be used to determine present topsoil K needs for cotton in the Mississippi Delta area based on a 1.5% critical leaf K level during the fifth week of flowering.     

Effect of nitrogen,phosphorus and potassium on yields and nutrient levels in onions grown on a sphagnum peat soil

Abstract

Onions were grown on two areas of sphagnum peat. One (old area) had been fertilized and cropped for a 5‐year period and the other (new area) had not. Fertilizer treatments on both areas consisted of an N, a P and a K series. Each nutrient was applied at four rates in combination with constant rates of the other two.

In practically all instances comparable treatments resulted in lower N, P and K levels in plant tissue samples from the new area than from the old where residual effects from previous cropping and fertilization were evident. Yield data indicate that initially, previously unfertilized sphagnum peat should receive N, P and K at 275–300, 40–50 and 70–80 kg/ha respectively.     

Exchangeable K levels for maximum crop yields on soils of different cation exchange capacities

Abstract

Wide differences in levels of exchangeable K considered adequate for maximum yields in different States are probably a consequence of the acceptance of either a single 200 pp2m rate for 95–987. sufficiency suggested by Bray, or a variable level based on a percentage of the soil cation exchange capacity (CEC) proposed by Bear. It now appears that sufficiency levels should vary with soil CEC, but not merely as a simple percentage of it. Moreover, the relatiorshlp in practice is complicated by such factors as leaching of K from coarse textured soils, and fixation of added K in, and release of native K from, non‐exchangeable forms in soils high in micaceous clay content. Since these influences occur widely in Ohio soils, the need for new field studies was recognized and implemented. Laboratory and growth chamber studies relating K sufficiency to energies of exchange were examined. Also, a new procedure used by the Ohio Soil Testing Laboratory for providing K sufficiency baaed on soil CEC and crop yield and composition is described.     

添加剂对玉米秸秆颗粒燃料结渣特性的影响

为了研究添加剂对秸秆类颗粒燃料抗结渣的机理,该文以玉米秸秆颗粒燃料为研究对象,通过添加MgCO3、CaCO3、Al2O3 3种添加剂,对其灰渣进行结渣特性、灰渣形貌、化学组成等试验研究。结果表明,添加添加剂后玉米秸秆颗粒燃料灰渣形貌发生明显变化,灰渣尺寸越小,表面越粗糙,孔洞较多;Si、K元素是玉米秸秆颗粒燃料引起结渣的主要元素,Mg、Ca元素与Si、K元素反应生成新的化合物而具有抗结渣效果;Al元素亦与Si、K等元素发生反应生成了新的硅酸盐类。即添加剂与秸秆中的Si、K等碱金属元素发生反应生成了新的化合物抗结渣。研究结果为解决秸秆类固体成型燃料结渣问题提供了理论依据。     

Potassium requirement in relation to grain yield and genotypic improvement of irrigated lowland rice in China

The yield of rice (Oryza sativa L.) has increased substantially with the development of new cultivars, but the role of potassium (K) requirement for the increase in grain yield and the genotypic advance is still unclear. In order to investigate this relationship a database of 1199 on‐farm measurements (harvest index 0.4) comprising > 400 modern rice cultivars was collected during 2005–2010 across major irrigated lowland rice–production regions of China. This was used to evaluate the relationships among K requirement, grain yield, and genetic improvement. Across all the sites and seasons, mean reciprocal internal efficiency of K (RIE‐K, kg K [t grain produced]^–1) was 19.8 kg K (t grain)^–1 and rice yield averaged 8.7 t ha^–1. Considering four levels of grain yield (< 7.5, 7.5–9, 9–10.5, and > 10.5 t ha^–1), the respective RIEs were 18.7, 19.4, 20.5, and 21.7 kg K (t grain)^–1. The gradual increase in the RIE‐K with yield was attributed mainly to the increase in straw and grain K concentration and the decrease in the K harvest index. The RIE‐K values for ordinary inbred, ordinary hybrid, and “super rice” were 18.5, 20.1, and 19.9 kg K (t grain)^–1, respectively. Examining the historical development of rice cultivars, the RIE‐K decreased from 40.9 (Nanjing1, early tall, inbred) in the 1950s to 19.8 (IR24, semi‐dwarf, ordinary inbred) in the 1970s, and then increased to 20.9 (Shanyou63, modern ordinary hybrid) in the 1980s and 20.6 kg K (t grain)^–1 (II‐you084, “super” rice) in the 2000s. This variation in RIE‐K among grain‐yield levels and cultivars highlights the importance of information on rice K requirement in calculating K balance and optimal K‐fertilizer rate for rice production.     

脐橙幼苗新老叶片养分含量对大、中量元素短期缺乏的差异性响应

  【目的】  对比大、中量养分短期缺乏下脐橙新、老叶片中11种必需元素含量及变化,并分析缺素导致的营养元素间的相互影响。  【方法】  以一年生枳砧纽荷尔脐橙幼苗为试材进行了砂培试验。以完全营养液为对照 (CK),设置缺氮 (?N)、缺磷 (?P)、缺钾 (?K)、缺钙 (?Ca)和缺镁 (?Mg)处理,测定不同处理脐橙叶片（老叶和新叶）生长指标及矿质元素含量。  【结果】  所有缺素处理均导致叶片叶绿素含量降低,生物量减少,以缺氮处理最为显著。缺氮降低了叶片N、Ca、Cu、Mo含量;缺磷降低了叶片P、K、Mo含量;缺钾降低了叶片K含量;缺钙降低了叶片N、Cu、Zn、Mo含量但增加了P含量;缺镁降低了叶片Ca、Mg、Zn、Mo含量但增加了K含量。以必需矿质元素为变量分别对各处理老叶和新叶进行主成分分析,老叶中第一主成分 (PC1)明显将缺钾处理与其他处理区分开,与对照相比,缺钾老叶离子组成变化为N (?3%)、P (+1%)、K (?71%)、Ca (+11%)、Mg (+39%)、B (+16%)、Mn (+11%)、Fe (+32%)、Cu (?7%)、Zn (+14%)、Mo (?63%);新叶中PC1明显将缺氮处理与其他处理区分开,缺氮新叶离子组成变化为N (?53%)、P (+8%)、K (+7%)、Ca (?14%)、Mg (+11%)、B (+55%)、Mn (+51%)、Fe (?14%)、Cu (?57%)、Zn (+4%)、Mo (?25%)。老叶和新叶中元素含量呈正相关的元素是N-Cu、N-Ca、Mg-Mn和Cu-Mo,呈负相关的是K-Zn。  【结论】  脐橙幼苗老叶对钾的短期缺乏反应最敏感,缺钾会显著降低老叶中K和Mo含量并增加Mg和Fe含量,而新叶对氮素的短期缺乏最敏感,缺氮显著降低新叶中N、Ca、Cu和Mo含量。短期缺少P、Ca和Mg对脐橙幼苗叶片中的养分含量影响较小。