APPLICATION OF BOX-BEHNKEN DESIGN AND RESPONSE SURFACE METHODOLOGY FOR OPTIMISATION OF BUTTERNUT (CUCURBITA MOSCHATA) FRUIT YIELD USING FERTILISERS AND PINCHING

Abstract

Butternut (Cucurbita moschata) production is constrained by poor agronomic practices such as suboptimal application of fertilizers and lack of appropriate pinching practices aimed at improving the number of female flowers. Moreover, many farmers mix animal manures and inorganic fertilisers in one hill without any recommended rates. The objective of this study was to apply Box-Behnken Design and Response Surface Methodology to optimize butternut fruit yield using poultry manure, NPK fertiliser and pinching. The experiments were conducted in two trials in 2019 and 2020 at Karingani ward, Chuka. A Factorial experiment laid down in Randomised Complete Block Design was used. The factors included poultry manure at three levels (0, 5 and 10 tons/ha), NPK at three levels (0, 100 and 200 kg/ha of NPK 17:17:17) and pinching at three levels (0, 4^th node and 6^th node). Butternut variety Atlas F₁ was used. Data was collected on the fruit yield. The input variables were modelled and maximised using Box-Behnken design (BBD) and Response Surface Methodology. The optimisation of the input variables revealed that the optimal levels of application of NPK and poultry manure that can lead to maximum yield of butternut fruits were 505 kg/ha of NPK and 8102 kg/ha poultry manure. The model also showed that pinching should be conducted 30 days after planting (equivalent to pinching at 3^rd node) for optimal butternut fruit yield. The study demonstrated that BBD can serve as an inexpensive tool in optimization of the butternut fruit production. However, there is need for further field studies to validate the findings of this study in order to accurately advice farmers on optimum combined application of manure, NPK and pinching time.