Research Of Controling Effect Under Different Agronomic Measures On The High Starch Sweet Potato

The growth condition of the sweet potato in the field was studied by the ways of crossing combination design of four factors and two times return, the four factors including density, applying amount of K fertilizer, height of shelving and picking; and the influence of the different agronomy cultivation measures upon the sweet potato yield was also discussed. The main results were as follows.1. The experiment result showed that different agriculture cultivation measures had inconsistent influence upon the growth potential of plant. Among them, the density played significant differences upon the growth potential of plant and the yield of the sweet potato, describe in detail as following: With the increasing of density, the total length of stems increased rapidly; the number of the branches and the whole or the big and middle size of root tubers added; and the weight of the top and the whole of the big and middle size sweet potatoes also added. Especially the density had the most outstanding effect on the length of the stem, the number of the whole or the big and middle size of root tubers and the weight of the whole or the big and middle size of root tubers, which were much significant difference.2. The K applying fertilizer made the total length of stems and the number of the stipites increase obviously, the LAI enhance and the weight of the whole or the big and middle size of root tubers add; it had the most outstanding effect on the LAI, which was most significant difference.3. The height of shelving made the total length of stems grow, the diameter grow, the number of the branches and stipites increase, and the weight of the top and the whole or the big and middle size of root tubers also increase. The content of plant chlorophyll was higher with higher height of shelving. Particularly, it had outstanding effect on the diameter and the total length of stems, both of them reached most significant difference; But the effect on the LAI and the number of the big and middle size of root tubers didn't reach significant level.4. The influence of the picking on LAI reached significantly different level, but that on the total length of stems, the diameter, the number of the branches, the stipites, the number and the weight of the whole or the big and middle size of root tubers, and the weight of top didn't reach significant level.5. The interaction between the density and the applying amount of K fertilizer made the total length of stems and the weight of the top increase, and the number or the weight of the big and middle size of root tubers add; especially it had outstanding effect on the later three indexes, which reached most significant difference. The interaction between the density and the height of shelving made the total lengh of stems increase, the stem diameter grow, the number of the branches and stipites add, and the weight of the whole or the big and middle size of root tubers also increase; especially it had outstanding effect on the stem diameter, which reached most significant difference. The interaction between the density and the pinching had much effect on the total lengh of stems, the stem diameter, and the weight of the whole or the big and middle size of of root tubers.6. The interaction between the applying amount of K fertilizer and the height of shelving had much effect on the the total lengh of stems, the number of the stipites, the LAI, the weight of top and the weight of the whole root tubers. The effect of the interaction between the applying amount of K fertilizer and the pinching on the total lengh of stems reached significant different.As talking about the effect of four factors on the plants' absorption of N, density reached significant level,on the other hand density didn't reached on the plants' absorption of K₂O and P. but the height of shelving reached significantly affected for plants' absorption of K₂O.7. The effect of the applying amount of K fertilizer reached most significant difference; and that of the height of shelving reached significant difference. The effect of the interaction between the two factors of the density, the applying amount of K fertilizer and the height of shelving didn't reached significant difference; Besides, the effect of the interaction between the applying amount of K fertilizer and the pinching on the yield didn't reached significant difference neither.8. To summing up, the optimizing cultivation model of high starch sweet potato species "YSW" was as follow: putting density 2810 seedlings/667 m², applying 20 Kg/667 m² of K fertilizer, taking the height of shelving for 1.5 m, picking the 7^th main stem apexes, the sweet potato species "YSW" could reach the highest yield in theory under this condition, it's 2781 Kg/667 m².