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991.
《Communications in Soil Science and Plant Analysis》2012,43(7):741-751
Abstract Some of the common methods used for the evaluation of available phosphate in soils were studied with respect to their power of releasing phosphate present in certain phosphatic compounds and in the sorbed form. Considerable differences in the amounts extracted were observed, The anion resin extracted relatively larger quantities from Ca than from Al or Fe phosphate materials. EDTA extracted very small amounts from the Al‐phosphates in comparison with the amounts obtained from the Ca and the iron materials. Ammonium fluoride at low pH released considerable amounts of phosphate from all the phosphate materials including sorbed phosphate. The quantities of phosphate extracted by sodium bicarbonate and water were relatively low as well as those determined by isotopic exchange. 相似文献
992.
通过在响水县油泥土地区进行的小麦磷肥效应试验,确定油泥土的土壤磷系数为0.84,有效磷的临界值为17.8 mg/kg。 相似文献
993.
In grassland farming, especially on coarse‐textured soils, K can be a critical element. On these soils, the actual K management as well as fertilizer history to a large extent determine the leaching of K. The effects of four fertilizer regimes on the nutrient balances and leaching of K from grassland grown on a sandy soil were investigated. The swards differed in the source and level of N input and K fertilizer: no fertilizer N + 166 kg K ha?1 year?1 (Control), 320 kg inorganic N ha?1 + 300 kg K ha?1 year?1 (MIN 320), 320 kg N + 425 kg K ha?1 year?1 in form of cattle slurry (SLR 320) and a grass–clover sward + 166 kg K ha?1 year?1 (WCL 0) without any inorganic N input. In a second experimental phase, cores from these swards were used in a mini‐lysimeter study on the fate of K from urine patches. On cut grassland after 6 years K input minus removal in herbage resulted in average K surpluses per year of 47, 39, 56 and 159 kg K ha?1 for the Control, MIN 320, WCL 0 and SLR 320, respectively. Related leaching losses per year averaged 7.5, 5, 15 and 25 kg K ha?1. Losses of urinary‐K through leaching were 2.2–4.5 and 5.7–8.4% of the K supplied in summer and autumn applications, respectively. Plant and soil were the major sinks for K from fertilizer or urine. High levels of exchangeable K in the soil and/or large and late fertilizer or urine applications stimulated leaching of K. 相似文献
994.
对河西绿洲灌区春小麦调亏灌溉2年后的土壤速效钾和全钾的变化进行了研究,并用配对样本t检验(双尾检验)对小麦收获时土壤钾素养分指标年际间的差异、土壤全钾与速效钾及其与全生育期调亏供水量间的关系进行了分析。结果发现,春小麦调亏灌溉对土壤钾素养分有明显影响,2004年小麦收获时0~20、20~40、0~40cm土层全钾、速效钾均显著低于2003年。回归分析发现,调亏灌溉春小麦收获时0~20 cm土层全钾和速效钾与小麦全生育期供水量呈线性正相关,0~20 cm和0~40 cm土层速效钾也随着全钾的增加呈显著线性增加的趋势。 相似文献
995.
AIM: To discuss the relevance between the pathogenesis of diabetic gastroparesis and the large-conductance calcium-activated potassium channels (BKCa) in gastric smooth muscle cells. METHODS: The SD rats were randomly divided into control group and model group. The gastric smooth muscle cells of the SD rats were enzymatically isolated in a low calcium solution containing papain. The current was recorded by patch clamp single channel recording technique. The expression of KCNMA and KCNMB1 were observed by the method of immunohistochemistry. RESULTS: The value of BKCa single channel conductance was (220.10±10.90) pS; the channels had distinct voltage dependent and calcium dependent characteristics. In outside-out patch (Vm =+30 mV), the activation of BKCa was blocked by 200 nmol/L IbTX completely. Compared with control group, the open probability and amplitude of current in model group significantly increased, while the mean open time and mean close time significantly decreased. Compared with control group, the expression of KCNMB1 in model group was significantly increased. CONCLUSION: Up-regulation of β1-subunit and increase in BKCa functional activities may be associated with diabetes gastroparesis in rats. 相似文献
996.
997.
《Communications in Soil Science and Plant Analysis》2012,43(15):2050-2061
A study was conducted to evaluate the effect of nitrogen (N) application, through an easily available and cheap source urea, on potassium (K) displacement and its availability in K-deficient maize-growing soils of rainfed subtropics. The greatest amount of K was displaced (11.22 kg ha?1) by N application at the rate of 80 kg N ha?1 (treatment T4). Amount of N fixed to displace K (11.10 kg ha?1) was also greatest in the same treatment. Displaced K was positively related to nonexchangeable potassium (NEK) release. Nitrogen application through urea at 80 kg ha?1 helped not only in meeting N requirement of maize crop in these N-deficient soils but can also satisfy the K requirements (as these soils are low in K) of these soils. Potassium displacement also increased the production efficiency of the maize crop by promoting its relative production efficiency index (RPEI) from suitability class V to class III. 相似文献
998.
D.?SivakumarEmail author R.?S.?Wilson Wijeratnam R.?L.?C.?Wijesundera M.?Abeyesekere 《Phytoparasitica》2002,30(4):403-409
Botryodiplodia theobromae, Colletotrichum gloeosporioides andGliocephalotrichum microchlamydosporum are the causal fungi of three rambutan postharvest diseases, stemend rot, anthracnose and brown spot, respectively. Two different
treatments of rambutan fruits to control the diseases were investigated: application of potassium metabisulphite (250 ppm)
or culture filtrate ofTrichoderma harzianum (TrH 40) followed by controlled atmosphere storage (CA) at 13.5°C and 95% r.h. Potassium metabisulphite at 250 ppm under
CA effectively controlled the incidence and severity of the three postharvest diseases and maintained the eating quality and
color of the fruit for 21 days. The greatest effect of this treatment was on brown spot disease, caused byG. microchlamydosporum. Application of TrH 40 was less effective than potassium metabisuphite.
http://www.phytoparasitica.org posting July 8, 2002. 相似文献
999.
中华绒螯蟹眼柄端髓X器官神经分泌细胞钙激活钾通道研究 总被引:1,自引:0,他引:1
采用膜片钳的内面向外式记录了中华绒螯蟹眼柄端髓X器官(MTXO)神经内分泌细胞钙激活钾通道活动。结果表明,在对称性高钾溶液中(200mmol.L-1),钙激活钾通道的单通道活动为快速开放的矩形方波,时程长短不一,通道电导为(213.4±11.2)pS。在-80~ 80mV钳制电压下,通道电流幅度及开放概率呈现明显的电压依赖性;随浴液游离Ca2 浓度的增加,通道的开放概率和开放数目增加,表现出明显的钙敏感性。药物敏感试验结果显示,80mmol.L-1四乙胺(TEA)可完全阻断通道活动。表明中华绒螯蟹眼柄端髓X器官(MTXO)神经分泌细胞钙激活钾通道(BKCa)具有大电导、电压依赖性、Ca2 敏感性和四乙胺(TEA)敏感性等特征。 相似文献
1000.
河西灌漠土施钾效应的定位试验研究 总被引:1,自引:0,他引:1
4年定位试验表明,小麦、玉米、甜菜单作条件下施K无明显效果。带状间作条件下小麦作物第3、4年出现施K显效效应,平均增产12.4%~14.9%;带田玉米当年出现施K效应,连续4年平均增产率为16%~27.9%。K肥对带田作物品质也有改善作用。 相似文献