Produksi dan kualitas kolesom dengan pemupukan organik dan inorganik

Abstract

Three consecutive field experiments had been conducted at the IPB experimental station (Bogor, Indonesia), in March-July 2011 to study the effect of two types of fertilizer on waterleaf [Talinum triangulare (Jacq.) Willd.] production and quality in wet (March-May 2011) and dry (May-July 2011) seasons; while laboratory analysis was conducted from April to December 2011. The first experiment was in wet season and consisted of two sets of treatment, namely different rates of organic [cow manure (ton/ha) + guano (kg/ha) + hull ash (ton/ha), i.e. 6.1 + 75.6 + 2.7, 9.2 + 151.2 + 4.1, 12.3 + 226.8 + 5.5, 15.4 + 302.4 + 6.8, and 18.4 + 378.0 + 8.2] and inorganic [urea (kg/ha) + SP-36 (kg/ha) + KCl (kg/ha), i.e. 50 + 20 + 50, 75 + 40 + 75, 100 + 60 + 100, 125 + 80 + 125, and 150 + 100 + 150] fertilizer. The second experiment was in dry season and consisted of two sets of treatment, namely different rates of organic and inorganic fertilizer (same as the first experiment). The third experiment was in dry season and consisted of four sets of treatment, namely different rates of organic (6.1 + 75.6 + 2.7, 12.3 + 226.8 + 5.5, and 18.4 + 378.0 + 8.2; the fertilizers and units were as above) and inorganic (50 + 20 + 50, 100 + 60 + 100, and 150 + 100 + 150; the fertilizers and units were as above) fertilizer, and organic and inorganic fertilizer residue (without fertilizer re-application). The experimental design for each set was randomized block design. Since fertilizer rates did not significantly affect the variables, means value of each set were compared by using t-student’s test. Generally, the result from these research suggested that (1) In wet season, waterleaf with organic fertilizer did not have any difference in shoot production; while in dry season, these treatments resulted in higher shoot production compared to those with inorganic fertilizer; (2) Waterleaf antioxidant capacity of organic and inorganic treatments were not significantly different in the same planting season; (3) The primary (vitamin C) and secondary (flavonoid) metabolites with antioxidant functions were higher in dry season compared to those in wet season; (4) Biosynthesis pathway of waterleaf phenolic compounds in wet season was different from that in dry season. It was suspected that phenolic compounds were synthesized predominantly via phenylpropanoid pathway in wet season and via acetate-malonate pathway in dry season; (5) Without organic or inorganic fertilizer re-application in the new planting season, yield of waterleaf shoot decreased approximately 26-50 % but did not degrade the quality.