Basal NPK and top-dressing N fertilizer requirements for improved growth and yield of Cucurbita argyrosperma in South Africa

Abstract

Cucurbita argyrosperma has edible shoots, flowers, fruits and seeds that are rich in nutrients and minerals. However, it is scarcely grown by local farmers in South Africa. This study aimed at establishing fertilizer requirements for its improved growth and yield under large scale farming. Plants were grown under different quantities of 2: 3: 4 (30) NPK basal fertilizer and nitrogen (LAN at 28% N) top-dressing. Shoots and leaves of C. argyrosperma plants treated with 300 NPK basal fertilizer at varying nitrogen top dressing, grew faster from 42 to 49 days after planting (DAP). Plants treated with the same fertilizer combinations had thicker stems, numerous leaves, higher leaf total chlorophyll content, heavier fresh shoots, numerous staminate and pistillate flowers, at 49 DAP. At harvest, the same fertilizer treatments resulted in higher number, mass and size of fruits and seeds. The majority of traits had positive correlation amongst each other but shoot moisture content correlated negatively with all traits. Almost all traits were positively defined in both principal component analysis and scatter plot. In a scatter plot, fertilizer treatments grouped themselves based on NPK basal fertilizer, with 300 NPK fertilizer at varying nitrogen being defined positively.