The Effect of Planting Depth on the Performance of the Irish Potato (Solanum tuberosum L.) Variety Larnoma in Nyanga District.

Abstract

The Irish Potato (Solanum tuberosum L.) is an important tuber crop on a global scale. In Zimbabwe potato ranks the third after maize and wheat and worldwide it is ranked the fourth after maize, wheat and rice. Potato is crucially important to food security in Zimbabwe. The Nyanga highlands are one of the production hubs for Irish potatoes in Zimbabwe but it has been noted that there has been a marked decline in potato yields over the years. The decline in yields is attributable to several factors with agronomic, pests and diseases and general climate change. Among the agronomic factors, the planting depth is a crucial factor in potato production but there is no tested and proven planting depth for the Nyanga area. The study aimed at determining the proper planting depth for Irish Potato variety Larnoma. The study was undertaken at two sites namely; Nyamurindi farm and Muozi farm in the 2019-2020 cropping season. Four planting depths of 5 cm, 10 cm, 15 cm and 20 cm were used. The trial was laid out in a Randomised Complete Block Design with field slope as the blocking factor. Parameters measured include average tuber weights per plot for large, medium and small sized tubers, average number of tubers per plot for large, medium and small sized tubers, average number of branches per plant, average stem length, percentage emergence, percentage flowering and the percentage of mature foliage at selected intervals until harvest. The data was subjected to Analysis of Variance using MINITAB version16 statistical package. The 5 cm and 10 cm depths had significantly higher rates of emergence compared to the 15 cm and 20 cm depths. The planting depth of 10 cm was noted to be the most suitable in the production of the tubers with the biggest proportion of heavy tubers and the biggest number of tubers per plot. The 5 cm depth and 10 cm depth had significantly earlier emergence and earlier flowering compared to the 15 cm and 20 cm depths. The size of potato tubers is an important quality criterion and it is affected by the planting depth. In this study it was noted that the 10 cm planting depth produced the largest proportion of large sized tubers at both Nyamurindi and Muozi farms. It is recommended that further studies be done in areas which are different from these two for another season in order to validate these results.