Effects of spacing and Negarim micro catchment on the growth of two provenances of Moringa (Moringa oleifera) in Kitui county, south eastern Kenya

Abstract

There has been an increased human population in arid and semi-arid areas. However, these areas are characterized by harsh climatic conditions hence low agricultural productivity, environmental degradation and over exploitation of natural resources. There's need to understand the best agronomic crop requirements for high value trees and shrubs like Moringa oleifera (Lamark) through climate smart agriculture. Limited studies on Moringa oleifera provenance trials, use of micro-catchments and spacing have been undertaken in Kenya; although it is widely grown and used in multiple ways in many rural areas. The study sought to determine the interaction between spacing, provenance and Negarim micro catchment on the growth of Moringa oleifera in Kitui County. Specific objectives of the study were to determine the effects of spacing on growth performance of two provenances of Moringa oleifera; to determine the effects of Negarim micro catchment on the growth performance of two provenances of Moringa oleifera under different spacing; and to determine the survival rate of two provenances of Moringa oleifera under different spacing and Negarim micro catchment. A 2 × 2 × 3 Factorial Randomized Complete Block Design was adopted. Spacing levels of 100 cm × 100 cm, 150 cm × 150 cm and 200 cm × 200 cm were considered when designing the field plots. Seedlings were raised in the South Eastern Kenya University Botanical Garden and nursery experiment began with the acquisition of seeds in Machakos and Gede. The experiment was set at the farm of Yumbisye Secondary School. Land preparation included removing of trees, uprooting of stumps, establishment of terraces, ploughing with a tractor, and harrowing to a fine till. Considering the land's gradient, suitable experimental sites were identified and three equal blocks created; where every band on the terrace served as an experimental block. The plots were positioned along the contour, and the ultimate land preparation was afterwards tailored to the actual experimental unit. Twelve treatment combinations for both experimental and control plots were generated, randomized within the plot and replicated thrice to 36 experimental units. Data was collected on a monthly basis for a period of 16 months (January 2018/April 2019). Plant height measurements was taken from the stem base to the terminal bud leaf using a graduated rule, root collar diameter measurements were taken at the soil level using Vernier caliper while branch development on the plant and surviving plants determined through manual counting. The data was cleaned, averaged and analyzed using GenStat Release 14.1 for Windows based on the objectives of the research. Gede provenance under Negarim micro catchment, mean plant height was 108.8 cm, mean root collar diameter was 5.5 cm, mean number of branches was 14, and mean seedling survival rate was 66 %. Control treatments mean plant height was 160.2 cm, mean root collar diameter was 7.3 cm, mean number of branches was 18, and mean survival rate was 74 %. The Machakos provenance's results under Negarim Micro Catchment revealed that mean plant height was 152.0 cm, mean root collar diameter was 5.5 cm, mean number of branches was 15, and mean seedling survival rate was 60 %. Control treatments for Machakos provenance reached a mean height of 117.7 cm, mean root collar diameter of 5.3 cm, a mean of 15 branches, and a mean survival rate of 65 %. Provenance and Negarim micro catchment had a significant effect on survivability (p≤0.05), height (p≤0.05), and branches development (p≤0.05). The significant differences of plants under Negarim Micro Catchment were because the catchment provided more moisture advantages to plants than those that were under no Negarim micro catchment. Spacing level of 150 cm × 150 cm under Negarim micro catchment as a suitable water harvesting technique can be recommended for inclusion in tree cultivation systems in the area and other places with similar climatic conditions in enhancing the growth and survival traits of Moringa oleifera.