Fermented seaweed juice of Caulerpa lentillifera increases the heading incidence of Brussels sprouts (Brassica oleracea L.) in tropical temperatures

Low atmospheric temperatures are required to induce heading in Brussels sprouts.However, the average atmospheric temperature in the Philippines is higher than what Brussels sprouts require. This study aims to test the effect of fermented seaweed juice of Caulerpa lentillifera (FSJ) on the incidence of heading in Brussels sprouts under tropical atmospheric temperatures. Aside from growth-promoting effects on some plant species, seaweed extracts are also reported to counteract the effects of biotic and abiotic stresses including high-temperature stress. 'Long Island' Improved Brussels sprouts were treated with increasing levels of FSJ (1%, 2%, 3% v/v) and increasing levels of FSJ combined with 1mM n-bromosuccinimide (anthocyanin inhibitor). The heat-resistant 'Hestia Hybrid' was used as the positive control. Treatments were applied by drenching 500 mL of treatment solution into the soil. The experiment was laid out in a completely randomized design having ten replicates per treatment. The number of heading buds and the total number of buds per plant were recorded. Data was analyzed using Statistical Tool for Agricultural Research. Increasing levels of FSJ significantly increased the percentage of heading sprouts of 'Long Island Improved' while the number of buds per plant is unaffected (alpha=0. 05). The heat-resistant variety 'Hestia Hybrid' has the highest incidence of heading sprouts at 95.35% (positive control) while the untreated 'Long Island Improved' variety is only at 453% (negative control). When 3% FSJ was applied, heading incidence rose to 71.56% exhibiting a direct proportion with the percentage of heading incidence in Brussels sprouts. The addition of 1mM n-bromosuccinimide did not significantly reduce the percentage of heading incidence. Greater than 3% FSJ concentrations could have increased the percentage of heading incidence further. It is concluded that FSJ has affected the incidence of heading in 'Long Island Improved' Brussels sprouts which may be explained by further molecular studies.