Effects of potassium application rates on dry matter accumulation,dry matter distribution,and potassium efficiency of sweet potato

Three rates of potassium(0,150 kg/hm2,300 kg/hm2) were applied to four sweetpotato varieties,purple sweet potato(NZ1),food sweetpotato(SU14),food and starch sweetpotato(SY303),starch sweetpotato(SU11).The dry matter accumulation,ratio of vines to tuberous roots,plant potassium accumulation,plant potassium utilization and potassium harvest index of sweet potato were determined.Compared to no potassium treatment,300 kg/hm2 potassium application increased the dry matter accumulation of SU11 and lowered the dry matter accumulations of NZ1 and SU14.Potassium application improved the ratio of vines to tuberous roots of NZ1,SU14 and SY303.Without potassium application,the theoretical yields of NZ1 and SU14 were higher than those of SY303 and SU11.The theoretical yield of SU11 was higher than those of NZ1 and SU14 applied with 300 kg/hm2 potassium.Therefore,SU11 is preferential variety for soils with sufficient potassium,and NZ1 and SU14 are preferential varieties for soils with insufficient potassium.