Effect Of Potassium Nutrition On Potassium Absorption And Yield Of Soybean

Soybean is one of the major grain and oil crop in China, it has rich nutritional value.Potassium is one of the necessary nutrients for growth and development of soybean plant. It is anactivator of enzymes, which plays an important role in promoting the growth and development ofsoybean plant. Studying on rule of potassium absorption, accumulation, distribution of soybean areprofound implications for appropriate application of potassium fertilizer, reduction in productioncosts, increase of soybean yield. The work was conducted with sand culture in the experimentalstation of Northeast Agricultural University from2011to2012. The experiment was divided intotwo parts named potassium nutrition test and interruption of potassium test. Seven potassiumlevels were set in the potassium nutrition test and potassium content were4,16,28,40,52,64and76mg/L, respectively. The interruption of potassium test was divided into interruption ofpotassium according to soybean growth period and15days periodic interruption of potassium. Therule of absorption, accumulation, distribution and transfer of soybean was researchedsystematically. The results showed that:（1）Potassium accumulation center changed as the soybean grew. Leaf was the Kaccumulation center and root followed in the vegetative growth of soybean. With the advancement of growth and development, soybean plant entered reproductive growth period, potassiumgradually transferred from vegetative organs to pod, which resulted in reduction of potassiumaccumulation in vegetative organs. The velocity of potassium accumulation of soybean plantorgans was the fastest at R2~R5stage and the one of potassium accumulation of pod increasedrapidly at R5~R7stage.（2）The lack of potassium made potassium of vegetative organs transferfrom the middle and lower parts to the upper part, which gave priority to the growth of soybeanplant. At the reproductive growth stage, the most of K was transferred to pod in order to guaranteepotassium that pod demanded（.3）The higher potassium level had obvious promotion of potassiumabsorption and accumulation in whole growth of soybean. With potassium level of nutrientsolution rising, potassium accumulation of soybean plant increased continuously. Potassiumaccumulation of whole plant was the smallest when the potassium level was4mg/L and potassiumaccumulation of whole plant was the largest when the potassium level was76mg/L.（4）Potassiumlevel had obvious influence on accumulation of soybean dry matter. The dry matter accumulationof whole plant was the lowest at the level of K4. There was no significant difference between K28and other higher levels, which indicated that soybean dry matter accumulation could be satisfiedwhen potassium level was28mg/L. And dry matter accumulation increased when potassium levelswere higher than28mg/L, but it did not reach a significant difference（.5）Soybean yield presenteda single peak curve with potassium levels. The effective pods number, seeds number and yield were the lowest when potassium level was4mg/L and soybean yield was the highest at level of K64.There was no significant difference between K28and other high levels in yield, which showed thatyield could be satisfied when potassium level was28mg/L. And yield of SN14increased whenpotassium levels were higher than28mg/L, but it did not reach a significant difference. Yield ofHN48increased slightly and it did not reach a significant difference, which showed that SN14ismore sensitive to potassium than HN48. Soybean plant height, effective pods number and seedsnumber presented a single peak curve with potassium levels. Potassium level had little influenceon100-seed weight and it did not reach a significant difference（.6）Potassium level was the crucialfactor for the formation of yield before seed filling period(R5). The interruption of potassiumresulted in potassium nutrition deficiency of plant and obvious decline of yield at R1~R5period,which could not be remedied at later periods. The interruption of potassium had little influence onyield at V3~R1period and potassium deficiency could be remedied by supply of potassium at laterperiods. Because potassium was supplied adequately in the early time, interruption of potassiumhad little influence on yield at R5~R7period and it did not reach significant difference.（7）Potassium level had obvious influence on the quality of soybean. The fat content increased firstlyand then decreased with potassium level rising, while the low potassium level was beneficial to theformation of protein. The interruption of potassium resulted that the protein content of soybeanwas increased significantly, while the fat content was significantly reduced at R1~R5period.