Germination of Noni (Morinda citrifolia L.) seeds as influenced by pre-treatment and sowing media

Abstract

Noni is a useful tropical fruit shrub, difficult to propagate due to seeds dormancy. Hence, a two-stage experiment was conducted to develop easily applicable rapid germination method for the crop. Firstly, seeds were subjected to different pretreatments [nicking, soaking in 50% H₂SO₄ for 5 min., 800 ppm GA₃ for 24 h, hot-water at 40°C for 24 h and control (untreated)]. Secondly, the most suitable pre-treatment method was applied to another set of seeds and sown in six sowing media [topsoil, river-sand (reference), sawdust, topsoil+river-sand (1:1), topsoil+sawdust (1:1) and river-sand+sawdust (1:1)]. A total of 2000 and 2400 seeds were sown in first and second stages, respectively. Each set of treatments was laid in completely randomised design with four replicates. Data collected were used to determine germination percentage (GP), mean germination time (MGT), germination index (GI) and mean germination rate (MGR). The results showed that there were significant differences (p ≤ 0.05) in the effects of the treatments for all the parameters considered at each of the stages. Nicking elicited highest GP (64.8%), MGR (0.026 sprouts/day), GI (1.79) and shortest MGT (38 days) at 12 weeks after sowing. Subsequently, the results of Morinda citrifolia seeds sown in different media indicated that topsoil/river-sand mixture significantly increased GP (81.5%) and GI (3.08) while topsoil gave highest MGR (0.038 sprouts/day) and shortest MGT (26.4 days). Hence, for commercial large scale seedling production, Noni seeds should be nicked and sowed directly in topsoil or a mixture of topsoil and river-sand.