Performance of Theobroma cacao (L.) Seedlings Irrigated with Water from Different Sources

Reliability of six irrigation water sources (stream, borehole, river, well, rain and sea) for raising cacao (Theobroma cacao L.; varieties F3 Amazon and Amelonado) seedlings was investigated, using 6x2 factorial experiment, replicated three times in completely randomized design. Plant vigor was assessed with height growth; stem girth, number of leaves, leaf area and canopy spread data taken at 3 weeks interval. Due to declining growth rate, seawater-irrigated seedlings` biomass production, percentage tissue Nitrogen (N) and percentage tissue Phosphorus (P) were evaluated at 9 Weeks after Sowing (WAS) while the same parameters were determined at 24 WAS for seedlings irrigated with water from other sources. Only stream- and rain- waters had pH < 8 while seawater had Electrical Conductivity (EC25) that was over 200 times higher than for each of the other sources. Seedling performance was best with stream water and poorest with seawater. Performance differences among seedlings irrigated with water from borehole, river, well and rain were insignificant (p<0.05) and similar to those irrigated with stream-water. Amelonado seedlings irrigated with water from borehole produced the highest fresh shoot biomass (60.38 g/pot) while river-water irrigated F3 Amazon had the highest fresh root biomass (11.09 g/pot). The fresh shoot and root weights of seawater treated seedlings were less than for each of the other sources. On drying, sea-watered F3 Amazon seedling recorded highest shoot and root weights` percentage losses (67.9 and 77.3%, respectively). Irrigation water alkalinity (pH) was inversely related to seedling leaf expansion while salinity (EC25) influenced biomass production and nutrient uptake negatively and percentage moisture positively, but had no influence on nutrient content in plant tissue. It was evident that water from the various sources apart from sea could be relied upon for use in cacao nurseries.