Multiple Regressions Analysis to investigate the optimal yield of Guava fruits at different level of NPK Fertilizers in south west Nigeria

Abstract

Purpose: This study investigates the effect of fertilizers (Nitrogen, Phosphorus & Potassium) on Guava; examines which of the three elements of NPK contribute most to the weight of guava seed. It thus further determines at what proportion each of the three elements is to be applied for optimum yield. Subjects and Methods: A 3 x 3 factorial experiments were adopted in the data analysis; further tests were conducted using different Post Hoc test approaches and a multiple regression analysis was derived to investigate at what proportion the elements are to be applied for optimum yield. Results: The results of the analysis of variance (ANOVA) showed that only Phosphorus and Potassium contribute to the growth and weight yield of guava. The Post-Hoc Tests showed that there was a significant difference between the mean pair of P0 & P20 and P0 & P40 with a p-value of 0.000 and 0.000 respectively. Also, there was a significant difference between the mean pair of K0 & K50 and K0 & P100 with a p-value of 0.004 and 0.008 respectively which is less than the significant level at 0.05. Furthermore, the overall multiple regression models for the weight yield of guava fruits were obtained as: (Y)=5.646+0.0556N-0.3611P+1.5694K+1.7167NP+1.1333NK+1.0361PK. Conclusion: Thus, to obtain an optimal yield of 12- 20t/ha of guava fruits, phosphorus and potassium are to be applied at 40k.g and 50kg respectively with spacing of 6 x 6m accommodating 277.7 plants per hectare.