Hardening Watering Interval of East African Greenheart (Warburgia ugandensis), Nursery Seedlings in East Mau Watershed, Njoro, Kenya

Water has been a scarce resource in agricultural areas and is essential in the establishment of nursery seedlings. This requires the effective and efficient use by farmers of this important resource. Hardening nursery seedlings through the reduction of watering regimes is necessary before transplanting seedlings to the field. This leads to better survival but when the interval of watering is not well established, and this might affect species and locality. An experiment was set up during the dry season just before planting out to determine the best hardening watering interval for East African greenheart (Warburgia ugandensis) seedlings in Egerton University, East Mau watershed, Njoro, in Kenya. The experiment was laid down as a Completely randomized design (CRD) with 5 treatments replicated 3 times. Treatments constituted of different watering intervals, which were: twice daily, once daily, 2 days, 4 days and 6 days. These treatments were applied for 60 days on 270 days old seedlings from January to March 2018. Analysis of variance (ANOVA) was used to determine treatment differences while DMRT determined the significantly different treatment means at p ≤ 0.05. The results revealed that the best growth was shown by twice daily, once daily, 2 days and 4 days intervals for shoot biomass, total plant biomass and total leaf area. However, the recommended watering interval is 4 days since it showed good growth for most of the variables with minimal water use equivalent to 12.5% of the water used by seedling watered twice daily which saves 87.5% of the water applied.  The results are applicable in the Kenyan highlands for Warburgia and other leafy succulent plants. However further studies needs to be done for other non-succulent species using different pot sizes and soil mixtures.