Karakter Fotosintesis Genotipe Tomat Senang Naungan pada Intensitas Cahaya Rendah (The Photosynthetic Characters of Loving-Shade Tomato Genotypes at Low Light Intensity) - Dwiwanti Sulistyowati; Muhammad Ahmad Chozin; Muhamad Syukur; Maya Melati; Dwi Guntoro (Indonesian Center for Horticulture Research and Development, 2016)
Salah satu upaya untuk meningkatkan produksi tanaman tomat di Indonesia adalah melalui sistem tanam tumpangsari atau agroforestri. Namun, dalam sistem tanam tumpangsari tanaman sela mengalami defisit cahaya karena ternaungi oleh tanaman lain. Defisit cahaya menyebabkan penurunan laju fotosintesis dan sintesis karbohidrat sehingga berpengaruh terhadap metabolisme. Beberapa jenis tanaman mampu beradaptasi terhadap defisit cahaya sehingga tumbuh di bawah kondisi naungan. Tujuan penelitian ini adalah mempelajari karakter fotosintesis genotipe tomat senang naungan pada intensitas cahaya rendah. Percobaan dilaksanakan di Kebun Percobaan Sekolah Tinggi Penyuluhan Pertanian (STPP) Bogor dari bulan Oktober 2014 sampai dengan Januari 2015. Percobaan menggunakan rancangan acak petak tersarang yang diulang tiga kali. Faktor pertama terdiri atas dua taraf naungan, yaitu tanpa naungan (0%) dan naungan 50%. Faktor kedua berupa tiga kelompok genotipe tomat terdiri atas senang naungan, toleran, dan peka. Pengamatan dilakukan terhadap komponen hasil berupa jumlah buah, bobot buah, dan produksi pertanaman. Peubah pengamatan fisiologi meliputi kandungan total klorofil, klorofil a, klorofil b, rasio klorofil a/b, antosianin, karoten, laju fotosintesis, konduktansi stomata, konsentrasi CO2 internal daun, kandungan pati, dan gula daun. Hasil penelitian menunjukkan bahwa genotipe tomat senang naungan jika berada pada kondisi ternaungi akan memiliki karakter fotosintesis berupa peningkatan kadar klorofil b lebih tinggi dibandingkan klorofil a, dan rasio klorofil a/b yang lebih rendah dibandingkan kelompok genotipe yang lain. Genotipe senang naungan memiliki konsentrasi CO2 internal daun lebih tinggi sehingga mampu mempertahankan laju fotosintesis tetap lebih tinggi walaupun terjadi penurunan konduktansi stomata. Adanya kandungan gula daun yang lebih tinggi, mengakibatkan produksi pertanaman genotipe senang naungan meningkat ketika ditanam di bawah naungan.KeywordsLycopersicon esculentum Mill.; Intensitas cahaya rendah; Karakter fotosintesis; Genotipe senang naunganAbstractEfforts have to be made to increase tomatoes production in Indonesia, one is through intercropping or agroforestry systems. In the intercropping system, however, there is a risk for plants to receive low light intensity. Low light intensity causes a decrease of photosynthesis rate and carbohydrate synthesis, so it will affect plant metabolic processes. Some types of plants are able to adapt to low light intensity, so they can grow well under shading conditions. The aim of this study was to investigate the photosynthetic characters of shade-loving tomato genotypes at low light intensity. The experiment was conducted in the experimental field of Bogor Agricultural Extension Institute, in Bogor, from October 2014 to January 2015. The experiment was arranged in nested randomized design with two factors and three replication. The first factor consisted of two levels of shading intensity, i.e. without shade (0%) and 50% shading and the second factor was three groups of tomato genotypes, i.e. shade-loving, shade-tolerant, and shade-sensitive genotypes. The crop yield components observed were fruit number, fruit weight, and yield per plant. Physiological variable measured were total of chlorophyll, chlorophyll a, chlorophyll b, ratio of chlorophyll a/b, anthocyanin, carotene, photosynthetic rate, stomatal conductance, leaf internal CO2 concentration, content of starch, and sugar leaves. The results showed that the photosynthesis characters of shade-loving genotypes indicated increasing content of chlorophyll b that was higher than that of chlorophyll a. It was resulting in decreasing ratio of chlorophyll a/b more than that of other genotypes. Shade-loving genotypes had higher internal leaf CO2 concentration, than the sensitive ones, so they can maintain the photosynthetic rate remained higher, despite their stomatal conductance were decreasing. The presence of leaf sugar content was relatively high, resulting in the production per plant of the shade-loving genotypes increased when grown in the shade conditions.