Response of Okra (Abelmoschus esculentus) varieties to NPK fertilizer in the southern Guinea savanna of Nigeria

Pot and field experiments were conducted to determine the response of three okra varieties to four NPK fertilizers. The okra varieties; V35 (in the pot experiment and  Clemson spineless in the field trial), Jokoso, and Sologo formed the main plot treatments and four NPK fertilizer rates: no fertilizer (control), 30 +15 +15, 60 +30 +30, and 60 +30 + 90 in kg NPK ha-1 were the subplot treatments arranged as split plot in RCBD replicated four times. Generally, varieties and fertilizer treatments had significant effects on the fresh fruit yields and chemical composition of okra. For the pot trial, variety V35 produced significantly highest fruit weight; 48 g plant-1, followed by Jokoso 34.5 g plant-1 and Sologo 28.4 g plant-1. Application of 60 +30 + 90 kg NPK ha-1 produced higher fruit weight than the application of 60 +30 + 30 and 30 +15 + 15 kg NPK ha-1 which produced higher fruit weight than the control treatment. Interaction effect between varieties and fertilizer rates was highly significant (P= 0.05). For the field trial, on the average, variety Jokoso produced significantly higher fruit yield; 11.4 t ha-1 than Sologo 4.5 t ha-1 and Clemson Spineless 4.3 t ha-1. Mean fruit yield was significantly (P= 0.05) higher with the application of 60 + 30 + 90 kg NPK ha-1 than the control. Application of 60 +30 + 30 and 30 +15 +15 kg NPK ha-1 had similar mean fruit yield as the control treatment. Jokoso had higher N, K, Ca, and Mg uptakes in fruit than Sologo and Clemson Spineless. From the results, it was evident that the okra varieties exhibited variations in fruit yields’ response to NPK fertilizer. For Clemson Spineless, application of 30 +15+15 kg NPK ha-1 influenced highest fresh fruit yield, Jokoso 60 + 30 + 30 kg NPK ha-1 and for Sologo application of 60 + 30 + 90 kg NPK ha-1 will suffice.