Seaweed extract from Ulva reticulata Forsskal as enhancer for seed germination, growth and yield of moneymaker tomato variety, Solanum lycopersicum L.

Seaweed Ulva reticulata Forsskal was found abundantly and caused a nuisance in seagrass meadow located at Merambong shoal, Sungai Pulai estuary, Johor due to nutrient loading activity from land reclamation and this natural resource, in turn, could be utilized as biofertilizer for sustainable agriculture. This study was conducted to (i) determine the proximate compositions and nutrients content of U. reticulata collected from Merambong shoal, Sungai Pulai estuary, Johor; (ii) determine the effects of different concentrations of U. reticulata extract on the germination variables of S. lycopersicum seeds, Moneymaker variety and; (iii) compare the effectiveness of the U. reticulata extracts with other commercial biofertilizer and chemical fertilizer in terms of development and growth, yield, and yield quality of the tomato variety. Ulva reticulata samples were collected in January, March, April, and May of the year 2017, from Merambong shoal, Sungai Pulai estuary, Johor, and they were analysed for proximate compositions and nutrients content. Ulva reticulata samples in this study contain 85.37% – 88.27% moisture, 13.48 g per 100 g – 22.64 g per 100 g ash, and 20.03 g per 100 g – 22.78 g per 100 g crude protein. The seaweed contains low crude lipid, 0.75 g per 100 g – 0.76 g per 100 g and fiber, 1.65 g per 100 g – 1.93 g per 100 g, which makes them less suitable to be consumed as food. All nutrients showed significant variation and with no specific trend across the months. Total N, Ca, Mg, Cu, Zn, Mn, and Fe were higher in the U. reticulata which makes them a potential source of nutrients for crops. These findings revealed that the U. reticulata could be used as biofertilizer, and the samples collected in May 2017 was selected to be extracted and further used in this study. The U. reticulata samples were processed to produce its aqueous extracts from dried (A) and fresh (B) seaweeds at the concentrations of 5%, 10%, 20%, 30%, 40% and 50%. The extracts were tested to evaluate the germination of tomato seeds, where the concentration of 0% was used as control. There were ten germination variables evaluated, namely, germination percentage (GP), final germination percentage (FGP), mean germination time (MGT), germination index (GI), coefficient of velocity of germination (CVG), germination rate index (GRI), first day of germination (FDG), last day of germination (LDG), time spread of germination (TSG), and seed vigour index (SVI). Ulva reticulata extracts at lower concentrations (5% A, 5% B, and 10% B) enhanced tomato seeds germination, where significantly highest GP (98.3 – 100%), GI (233 – 250), and SVI (41.4 – 49.2), and significantly lowest MGT (4.5 days – 5.4 days), FDG (3 days), LDG (8.3 days – 10.7 days), and TSG (5.3 days – 7.7 days) were recorded. The results also indicated that application of 5% A, 5% B, or 10% B promoted up to 5 days faster to germinate completely as compared to control which took approximately 14 days and significantly higher seed vigourity as compared control as the presence of nutrients in the seaweed extract to enhance germination. Application of higher concentrations of fresh U. reticulata extract (> 20% B) inhibited tomato seeds germination due to contained higher in salinity. The effectiveness of the dried and fresh U. reticulata extracts at the concentrations of 5%, 10%, 20%, 30%, 40% and 50% were further tested on the tomato variety in the field for a period of 12 weeks (September 2017 to January 2018) in comparisons to commercial biofertilizer (Biofert) and chemical fertilizer (Chemfert) to assess development and growth, yield, and yield quality. Distilled water was used as a control. The treatments were applied weekly (100 mL) by soil drenching and foliar spray to tomato plants. The tomato plant’s height was significantly affected by the application of the treatments beginning week 3 to 6 after transplanted and reached a plateau at week 11 after transplanted. Treatment, 50% B, showed superior performance in terms of plant’s height, where the height recorded was 15.3 cm on week 3 and reached 49.52 cm on week 6. However, it recorded the lowest yield per plant (23.38 g plant-1) and lowest total yield (140.30 g). The use of other treatments showed fluctuation across the week. Tomato plants applied with Powder, 30% A, 30% B, and 40% B showed the earliest development of flower bud (week 2), early fruiting (week 5), and harvesting (week 10). Application of 40% A showed the highest total yield per plant (106.96 g plant- 1), which was 3 times more than control and 2.5 times more than plants treated with chemical fertilizer. Also, treatment 40% A yielded 75.69% of ripening fruits. Generally, the use of dried U. reticulata extract resulted in better total and ripen yield as compared to the fresh extracts, and increasing the concentration of the fresh extract >20% reduced the yield. No significant differences in fruit’s firmness, total soluble solids, and titratable acidity were found. The ascorbic acid, lycopene, and beta-carotene contents in the tomato fruits were affected by the treatments applied, However, no specific pattern was observed as the concentration of seaweed extracts was increased. The application of 40% A, produced tomato fruits with the highest quality in terms of ascorbic acid (27.88 mg/100 g) and lycopene contents (0.45 mg/100 g), where the lycopene content was 2 times more than Chemfert, and 1.4 times more than Biofert. Different concentrations of seaweed extract resulted on different characteristic of the tomato plant’s growth and yield and fruit quality. Therefore, either 5% A or 5% B was recommended to be applied to promote the tomato seeds germination, in addition to the application of 40% A in the field stage to promote better yield and yield quality. Seaweed extract contained abudance of nutrients to promote the growth, development and yield of tomato. The use of U. reticulata extract could be a better substitute for the use of chemical fertilizer or other commercial biofertilizers for more sustainable and eco-friendly production of tomatoes.

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