Abstract:
Quality seedlings are vital for productive coconut cultivation. Polybagged coconut
seedlings are ideal planting materials as they are superior in quality to conventional
bare-rooted seedlings. The recommended potting mixture of polybag consists of topsoil,
cow dung, and coir dust in a 1:2:3 ratio, featuring a significant amount of coir dust.
However, the high export potential of coir dust has rendered it a limited and scarce
resource in Sri Lanka. The present study has identified alternative materials as
substitutes for coir dust in the potting mixture of coconut polybag seedlings. Three
month-old coconut seedlings of variety CRIC 60 with similar sprout length were
established in polybags filled with five different media; T1: coir dust, T2: sawdust, T3:
half-burned paddy husk, T4: paddy husk and T5: paddy straw in combination with soil:
cow dung in 3:1:2 ratio. The experiment was laid out in a Randomized Complete Block
Design with three replicates. Days taken for the emergence of the first leaf,
morphological characteristics of the seedlings, relative chlorophyll content of leaves,
and soil properties were recorded. Data were analyzed using the Analysis of Variance
procedure in R software. Stem girth, seedling height, length and width of leaves, and
relative chlorophyll content of leaves were not significantly (p>0.05) different among
treatments two months after transplanting. Soil pH and electrical conductivity of potting
mixtures were in the desirable range in all treatments. In conclusion, freely available
sawdust, paddy straw, and paddy husk can effectively be incorporated into the potting
mixture of coconut polybag seedlings as a low-cost substitute for coir dust. Soil nutrient
analysis is suggested before any recommendation.
