钾对瓜尔豆光合及胚乳中糖类含量的影响

Effects of potassium on photosynthesis and endospermous carbohydrates contents of Guar [Cyamposis Tetragonoloba(L.) Taub.]

研究了钾对盆栽瓜尔豆光合及胚乳中糖类物质含量的影响。试验设4个施钾水平:K2O 0(CK)、8.952、13.381和17.857 mg/kg,分别用K1、K2、K3和K4表示。结果表明,增施钾肥可显著提高瓜尔豆叶片中可溶性蛋白、叶绿素含量和净光合速率,并且延长了光合峰值持续时间。在施钾条件下,生长前期叶片中蔗糖(Suc)和葡萄糖(Glc)含量与对照差异不显著;株龄60 d后,增施钾的处理叶片中Suc和Glc含量显著低于对照,子粒中的可溶性总糖、鼠李糖(Rham)、半乳糖(Gal)、Suc含量及多糖总量显著高于对照。不同处理的产量顺序为K3>K2>CK和K4;胚乳中半乳甘露聚糖(GM)含量为K2>K3和CK>K4。由于增施K2O 13.381 mg/kg的处理产量最高,其单株生产的糖物质及GM总量也最多。适量增施钾肥能显著提高瓜尔豆叶片的净光合速率,加速糖类物质由叶片向子粒中的运转,促进子粒中糖类物质的积累,提高子粒的产量。

Guar [ Cyamposis Tetragonoloba （L.） Taub. ] is an important raw material of guar gum. Galactomannan, an active ingredient of the gum, is generally found to be negatively correlated with seed yield of guar. An experiment was conducted in pot to determine the effects of four potassium （K） fertilizer level [K1 = 0 （control）, K2 = 8.952,K3 = 13. 381 and K4= 17. 857 mg/kg soil] on guar photosynthesis, chlorophyll content, soluble protein content of leaf, and endospermous carbohydrates accumulation. Supplying K significantly increased protein and chlorophyll content, enhanced net photosynthetic rate （NPR） of leaf, and extended high photosynthetic duration of guar leaf. Sucrose and glucose content in the leaf showed no difference under different K treatments in the early days. 60 days after emergence, however, sucrose and glucose content in the leaf treated with K fertilizer were lower than that of the control. K increased total soluble sugar, rhamnose, galactose, sucrose and gross polysaccharide content in the seed significantly compared with the control. The highest grain yield was found in K3, while the lowest was found in control and K4. Galactomannan relative content in the seed endosperm was the highest for K2, followed by K3, control and K4. The gross sugar and GM produced per plant in K3 was the highest due to its highest yield obtained. All the results indicated that K fertilization could enhance leaf photosynthesis, accelerate the transportation of sugar from leaf to seed, promote carbohydrates accumulation, and increase grain yield.