SUMMARY
Abstrak. Penelitian ini bertujuan untuk mengetahui distribusi enzim nitrat reduktase pada tanaman cabai merah (C. annum) yang dipengaruhi oleh berbagai faktor fisiologis. Percobaan ini menggunakan Rancangan Acak Lengkap dengan banyak faktor diantaranya: Faktor organ tanaman, umur tanaman, posisi daun dan pemupukan dengan nitrat. Berbagai organ tanaman cabai direndam dalam buffer fosfat pH 7,5 selama 20 menit. Setelah itu dilakukan penambahan susbtrat berupa 0,1M NaNO3 dan diinkubasi selama 60 menit. Sampel selanjutnya direndam dalam larutan Napthylediamine dan Sulfanilamide 1:1. Absorbansi sampel diukur dengan spektrofotometer pada panjang gelombang 540nm. Berdasarkan pengukuran absorbansi diperoleh hasil bahwa tanaman cabai usia dewasa memiliki aktivitas nitrat reduktse lebih tinggi dibandingkan dengan usia muda dan tua. Aktivitas nitrat reduktase pada organ daun lebih tinggi dibandingkan organ akar, batang dan buah. Sementara itu daun pada posisi pucuk memiliki aktivitas nitrat reduktase lebih tinggi dibandingkan dengan daun di posisi pangkal dan tengah. Pemupukan nitrat tidak memberikan pengaruh yang signifikan terhadap aktivitas nitrat reduktse pada tanaman cabai. Berdasarkan hal tersebut, dapat disimpulkan bahwa Capsicum annum usia dewasa memiliki aktivitas nitrat reduktase tertinggi dengan kecenderungan organ daun memiliki aktivitas nitrat reduktase terbesar dibandingkan organ lainnya terutama daun pada posisi pucuk. Penambahan susbtrat NaNO3 tidak memberikan pengaruh secara signifikan terhadap aktivitas nitrat reduktase. Distribution of Nitrate Reductase Enzymes in Red Chili (Capsicum annum) in Order to Support Sustainable Agroforestry Systems Abstract. This study aims to determine the distribution of the enzyme nitrate reductase in red chili plants (C. annum) which are influenced by various physiological factors. This experiment uses a completely randomized design with many factors including: Plant organ factors, plant age, leaf position and fertilization with nitrates. Various organs of chili plants are immersed in phosphate buffer pH 7.5 for 20 minutes. After that the addition of susbtrat in the form of 0.1 M NaNO3 and incubated for 60 minutes. The samples were then immersed in Napthylediamine and Sulfanilamide 1: 1 solutions. Sample absorbance was measured by a spectrophotometer at a wavelength of 540 nm. Based on absorbance measurements, the results showed that adult chili plants had higher nitrate reductase activity compared to young and old age. The activity of nitrate reductase in leaf organs is higher than that of root, stem and fruit organs. Meanwhile the leaves in the shoot position have higher nitrate reductase activity compared to the leaves in the base and middle positions. Nitrate fertilization did not have a significant effect on nitrate reductase activity in chili plants. Based on this, it can be concluded that the adult age Capsicum annum has the highest nitrate reductase activity with the tendency of leaf organs to have the greatest nitrate reductase activity compared to other organs, especially leaves in the shoot position. The addition of NaClO3 does not significantly influence the activity of nitrate reductase.