大量元素鉀ppt課件-在線瀏覽
2025-06-20 22:05本頁面
【正文】 點(diǎn)。但目前我國的鉀肥產(chǎn)量僅有 50— 60萬噸。 1996年生產(chǎn)能力達(dá)５０萬噸。 這一產(chǎn)量將占中國年度進(jìn)口鉀肥總量的三分之一。 中國最大鉀肥生產(chǎn)基地的第一步，一期建成 20萬噸硫酸鉀廠，最終計(jì)劃是年產(chǎn) 220萬噸鉀肥。 (ⅱ ) Fixed Kslowly available, 110%。 (ⅳ ) Soil solution Kreadily available, %. There is an equilibrium between the various forms Organic K is only a small part. Release and fixation of K+ and NH4+ ions by soil clay Section 2 Molecular and physiological aspects of potassium uptake in plants K is the most abundant cellular cation, with cytoplasmic concentrations regulated between 80 and 200 mM, and total tissue concentrations of approximately 20 mM. The transport of K+, which is mobile in plant, has been studied intensively for the last 50 years. K+轉(zhuǎn)運(yùn)進(jìn)入植物和在植物中運(yùn)輸?shù)哪Ｊ綀D 2. 1 Early Physiological and biochemical studies indicated the existence of multiple K+ transporters Excited roots (Hoaglant and Broyer， 1936） Epstein was first to treat radioisotopes to quantify ion efflux. Epstein was first to treat mineral ion transporters as enzyme kiics to studies of concentrationdependent root K+ uptake. Dual isotherm of K absorption Highaffinity K+ transport was thought to dominate at low concentration of K+ in soil, whereas as higher K+ concentrations, a lowaffinity K+ transporter operated that was less specific for K+ over other alkali cations. 硫基修飾的 N –乙基馬來亞銨（ NEM） :抑制髙親和力轉(zhuǎn)運(yùn)蛋白但不影響低親和力轉(zhuǎn)運(yùn)蛋白。 A very high affinity for K+ (Km=5 to 30 181。 A strong selectivity for K+ and Rb+ over other alkali cations. Lowaffinity K+ uptake system: Less selective for K+ and Rb+。 M）溶液中將引起膜電位的強(qiáng)烈的去極化。 植物中存在兩種類型的 K+通道： 內(nèi)流型通道（ inward rectify K進(jìn) ）和外流型通道（ outward rectify K出 ） 內(nèi)流型通道（ K進(jìn) ）在 Em（ － 50～－ 150 mV）超極化時(shí)打開促使吸收 K+。 研究表明低親和性鉀吸收的 1個(gè)主要成分是內(nèi)向整流通道（ K進(jìn) ）。 內(nèi)流型通道和外流型通道均具有較高的 K+/Na+選擇性，受 TEA和 Ba2+的抑制。 K+ /H+ cotransport system 毎 2各 H+由 ATP酶運(yùn)出細(xì)胞后，其中的 1各又經(jīng)由 K+ /H+同向共運(yùn)轉(zhuǎn)蛋白返回細(xì)胞中。 在根部， 可能存在 一種或幾種髙親和力 K+轉(zhuǎn)運(yùn)蛋白 ，它們由 H+—ATP酶提供能量，以 K+ /H+同向共運(yùn)轉(zhuǎn)的形式發(fā)揮功能。 Many plant genes encode K+ transporters KAT1
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