Leaf area index, chlorophyll, photosynthesis rate of lettuce (Lactuca sativa L) under N-organic fertilizer

N-organics. Research was conducted at Faculty of Animal and Agricultural Sciences, Diponegoro University, Indonesia. The materials used were seeds of lettuce (Lettuce sativa L) on Oxisol soil types, with the total N content of 0.18%, P (18 mg. g⁻¹), K (23 mg. g⁻¹) and C (1.52%) were utilized. The organic fertilizers applied were cow-, sheep-, and guano manures, and compost and green manure (Leucaena leucocephala). The experimental design was a randomized block design with four replications and five treatments. The treatment dose of fertilizer applied is equivalent to 100 kg N/ha, namely: cow-manure; sheep-manure; guano manure; compost and green manure. Green manure, set into the ground is Leucaena leucocephala. The variables measured were the number of leaves, leaf area, leaf area index(LAI), the rate of photosynthesis, Chlorophyll total, anti-oxidant activity, fresh weight of lettuce per plot. The data obtained were analyzed using an ANOVA followed by the Duncan test. Guano fertilizer provided the most excellent effect on leaves, LAI, the rate of photosynthesis and biomass lettuce. Fertilizers derived from animal manure (guano, cattle, goats) gave a more excellent effect on the rate of photosynthesis of plants. Compost origin gave the lowest effect on leaf area, LAI, and the rate of photosynthesis. The number of leaves, total chlorophyll, and antioxidant content were not influenced by the different organic N fertilizers.