PERFORMANCE OF SWEET POTATO (IPOMOEA BATATAS [L.] LAM) VARIETIES AS INFLUENCED BY ORGANIC-MINERAL FERTILIZER RATE AND STEM CUTTING LENGTH IN THE NIGERIAN AGRO-ECOLOGICAL ZONES

Abstract

A Field experiment was conducted in 2015 and 2016 wet seasons at the Research farms of the National Horticultural Research Institute Bagauda Sub-Station, Kano State and the Institute for Agricultural Research Ahmadu Bello University, Samaru-Zaria in Kaduna State. The study examined performance of sweet potato varieties as affected by organic- mineral fertilizer rate and stem cutting length in Nigerian Agro-ecological zones. The treatments consisted of two varieties of sweet potato (Dan Zaria, local variety and Mothers Delight), three rates of Organic-mineral fertilizer, (NPK 7: 7:7 with 20% organic matter) (at 0, 300 and 600 kgha^-1) and  300 kgha^-1 NPK (20-10-10) as a check and three stem cutting lengths (15, 30 and 45 cm). The treatments were laid in a randomized complete block design in a split plot arrangement. The combination of organic-mineral fertilizer rates and stem cutting lengths were assigned to the main plot and the varieties were assigned to the sub-plot, and replicated three times. It was found that Mothers Delight was superior to Dan Zaria variety in growth parameters, such as number of leaves per plant, crop growth rate, leaf area index and yield attributes such as number of tubers per plant, tuber diameter per plant and total fresh tuber yield. Application of organic- mineral fertilizer at 600 kgha^-1 or NPK fertilizer at 300 kgha^-1 significantly had greater numbers of tubers in 2015 at Bagauda and in both years at Samaru, more leaves and higher leaf area index in both years at Bagauda and Samaru. On the other hand, stem cutting length of 45cm gave higher measured growth and yield attributes, compared to the two other cutting lengths at both locations in both years. In conclusion, Mothers Delight was superior to Dan Zaria for its higher growth and yield attributes and total fresh tuber yield. While 600 kgha^-1 OMF (organic-mineral fertilizer) produced the highest growth and yield attributes and total fresh tuber yield.