Analysis of physiology and yield of amaranth (Amaranthus tricolor L.) in several organic fertilizer dosages

Physiological characters reflecting processes of dry matter accumulating in plant, that will be harvested as yield crop growth rate (CGR), relative growth rate (RGR), and net assimilation rate (NAR) are physiological characters which are often be used to predict the plant production. This research aimed to study: (1) physiological characters different of three amaranth cultivars which were cultivated in several organic fertilizer dosages, (2) yield different of three amaranth cultivars which were cultivated in several organiic fertilizers dosages and (3) interaction between fertilizer dosage and cultivar in several organic fertilizer dosages. This research was conducted at experiment field of Soybean Research and Development Center (SRDC) UNSOED, Karangwangkal Village, Purwokerto Utara District, Banyumas Regency, from April to June 2003. The experimental research was Randomized Complete Block Design (RCBD) with factorial arrangement and three replications. Factors observed were: fertilizer dosage: P0 (without fertilizer), P1 (10 t/ha organic fertilizer), P2 (15 t/ha organic fertilizer), P3 (20 t/ha organic fertilizer), and cultivar: V1 (Cempaka 20), V2 (Amaranth alabama), and V3 (local red). Variable observed, were: plant height, fresh weight of plant, dry weight of plant, number of leaf per plant, leaf area per plant, crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), yield per effective plot (1 square m), and yield per hectare. Result of the research showed that: (1) physiological character (CGR, RGR, and NAR) of Cempaka 20 cultivar was higher than Amaranth alabama and Local red cultivars (2) mean yield of Cempaka 20 (2.833 kg/square m) cultivar was higher than Amaranth alabama (2.788 kg/square m) and Local red (2.684 kg/square m) cultivars, (3) there was interaction between organic fertilizer dosage and cultivar for plant height and fresh weight variables (each cultivar showed different respons to organic fertilizer dosage), and (4) the best organic fertilizer dosage applied was 20 t/ha for Cempaka 20, Amaranth alabama, and 15 t/ha for Local red cultivars.