Effect of Potassium and microbial-organic fertilizer dosage on the growth and tuber yield of Japanese sweet potato (Beniazuma) (Ipomoea batatas Lam.) planted at Van Ninh district, Khanh Hoa province
Abstract
Potassium is an important nutrient for the growth and tuber yield of sweet potato. Microbial-organic fertilizers improve soils, transfering indigestible nutrients into the digestive elements for plant. The experiment was carried out to determine optimal dosage of potassium and microbial-organic fertilizer for good growth and higher tuber yield in Japanese sweet potato (Beniazuma) cultivation. The experiment was set up in a randomized completed block design with 8 treatments and three replications. The treatments consisted of 4 potassium levels (100, 150, 200 and 250kg K 2 O.ha -1 ) and 2 microbial-organic fertilizer levels (700 and 900kg.ha -1 ). The results showed that the increased dosage of potassium up to 200kg K 2 O.ha -1 and microbial-organic fertilizer increased the vine length, branche number, tuber number per plant, commercial rate of tuber roots, starch content, harvest index and tuber yield. 200kg K 2 O combining with 900kg microbial-organic fertilizer per hectare has tuber yield of 32.38 tons.ha -1 , increasing 37.4% in comparison with farmer’s level (100kg K 2 O and 700 kg microbial-organic fertilizer per hectare). The dosage of 200 kg K 2 O combining with 900 kg microbial-organic fertilizer per hectare should therefore be recommended level for Japanese sweet potato cultivation at Van Ninh district, Khanh Hoa province.