Performance and quality attributes of okra (Abelmoschus esculentus (L.) Moench) fruits grown under soil applied Zn-fertilizer, green biomass and poultry manure

Field experiments were carried out in 2018 and 2019 cropping seasons at Landmark University Teaching and Research farm, Omu-Aran Kwara state, Nigeria, to determine the effect of soil applied Zn-fertilizer, Tithonia diversifolia (Ti), Chromolaena odorata (Ch) and poultry manure (PM) on the performance, yield, minerals and vitamins composition of okra fruits. Treatments were combined and tested as follows:—Control (T(1)), Control + 10 kg ha(−1) Zn (T(2)), 5 t ha(−1) Ti + 5 t ha(−1) PM (T(3)), 5 t ha(−1) Ch + 5 t ha(−1) PM (T(4)), 5 t ha(−1) Ch + 5 t ha(−1) Ti (T(5)), 10 t ha(−1) Ti + 0 kg ha(−1) Zn (T(6)), 10 t ha(−1) Ti + 10 kg ha(−1) Zn (T(7)), 10 t ha(−1) Ch + 0 kg ha(−1) Zn (T(8)), 10 t ha(−1) Ch + 10 kg ha(−1) Zn (T(9)), 10 t ha(−1) PM + 0 kg ha(−1) Zn (T(10)), and 10 t ha(−1) PM + 10 kg ha(−1) Zn (T(11)). The experiment was laid out in a randomized complete block design with four repetitions. Vegetative, yield and quality parameters of okra were taken. Data were subjected to analysis of variance and means were compared using Duncan Multiple Range Test (DMRT) at p ≤ 0.05. Variations were observed on the vegetative parameters, yield, minerals and vitamin composition of okra among the applied amendments. The combined application of green biomass, poultry manure, and Zn-fertilizer improved all the variables tested as compared to when they were applied singly. Application of Zn-fertilizer to some selected plots significantly increased yield, Zn, Mg and vitamins concentration of okra. Application of 5 t ha(−1) Ti + 5 t ha(−1) PM + 10 kg ha(−1) Zn (T(3)) and 5 t ha(−1) Ch + 5 t ha(−1) PM + 10 kg ha(−1) Zn (T(4)) significantly improved all the parameters tested but the use of 5 t ha(−1) Ti + 5 t ha(−1) PM + 10 kg ha(−1) Zn (T(3)) resulted in optimum yield and at the same time increase minerals and vitamin concentration of okra. The results of this study therefore showed that Tithonia diversifolia (Ti) as green biomass contained and released more and quality nutrients than Chromolaena odorata (Ch) when combined with equal rate of Zn fertilizer and poultry manure.