Growth, shoot production, and metabolite content of waterleaf (talinum triangulare (jacq.) willd) with repeated organic fertilization.

Abstract

Waterleaf (Talinum triangulare (Jacq.) Willd) can be consumed as vegetable by consuming its shoot. Waterleaf is known as functional vegetable because the shoot contains some bioactive compounds to maintain human health. The purpose of this research was to investigate the effect of organic fertilizer combination to growth, production and metabolite content of waterleaf i.e. vitamin C, flavonoid, and peroxidase (POD) activity in the first and second planting season and organic fertilizer residue with repeated harvesting. This research was conducted at Leuwikopo Darmaga Bogor and Plant Analysis and Chromatography Laboratory, Department of Agronomy and Horticulture, IPB in November 2012-May 2013. The organic fertilizers were cow manure (CM), rock phosphate (RP) and rice-hull ash (HA). The fertilizer was combined into four combinations, CM + RP, CM + HA, RP +HA, and CM +RP +HA; with one control (without fertilizer). Treatment was arranged with randomized completely block design with three replications. Two experiments were set in the second season, i.e. the effect of organic fertilizing in the second season and the effect of organic fertilizer residue. The result showed that organic fertilizer gave same effect on growth, shoot production and metabolite content of waterleaf. Vitamin C was positively correlated to flavonoid content while flavonoid and vitamin C content was negatively correlated to K. Low rain intensity in the second harvest increased POD activity while flavonoid content decreased that was caused by precursor competition in flavonoid and lignin biosynthesis. Lignin biosynthesis is catalyzed by POD enzyme. Application of organic fertilizer in the second season increased growth, production, and metabolite content of waterleaf shoot. Cow manure + rock phosphate + rice-hull ash treatment gave the highest increase of shoot production compared to control treatment. Organic fertilizer residue from first season gave the same effect on growth and shoot production compared to control treatment. There was no significant difference effect between residual effect and organic fertilizer added in the second season. Growth and shoot production in the second season was lower than first season that was caused by low of rain intensity that inhibited the growth of waterleaf. The same condition also occurred in waterleaf metabolite content. Vitamin C content decreased in the second season while flavonoid content increased.