ABSTRAK Rindhy Qisthina. 2013. Pertumbuhan Flush dan Aktivitas Fotosintesis Bibit Durian (Durio zibethinus Murr) ‘Monthong’ yang Disemprot Boron. Dibimbing oleh Nursuhud dan Kusumiyati. Penelitian ini dilakukan untuk mengetahui pengaruh penyemprotan Boron dan konsentrasinya yang tepat terhadap pertumbuhan flush dan aktivitas fotosintesis bibit durian ‘Monthong’. Penelitian ini dilaksanakan di Kebun Percobaan, Fakultas Pertanian Universitas Padjadjaran pada bulan Mei 2012 hingga September 2012. Penelitian ini menggunakan metode deskriptif komparatif eksplanatif. Perlakuan dalam penelitian ini terdiri dari lima taraf konsentrasi Boron yang berasal dari asam borat (0, 500, 1000, 1500 dan 2000 ppm). Aplikasi Boron konsentrasi 500 ppm cenderung meningkatkan pertumbuhan flush dan aktifitas fotosintesis bibit durian Monthong. Aplikasi 500 ppm Boron pada bibit durian Monthong memberikan jumlah flush, jumlah daun per flush, jumlah daun per tanaman, luas daun per flush, luas daun per tanaman dan aktivitas fotosintesis tertinggi dibandingkan dengan aplikasi 1000 ppm, 1500 ppm, 2000 ppm dan tanpa Boron. Kata kunci : Boron, durian Monthong, flush, aktivitas fotosintesis ii ABSTRACT Rindhy Qisthina. 2013. Flush Growth and Photosynthesis Activity of Nursery Plants Durian (Durio zibethinus Murr.) ‘Monthong’ that Sprayed by Boron. Supervised by Nursuhud and Kusumiyati. This experiment aimed to determine the effect of Boron foliar spray and to obtain its exact concentration for flush growth and the photosynthesis activity of nursery plants durian ‘Monthong’. The experiment was conducted at Experimental Field, Agriculture Faculty, Padjadjaran University from May 2012 to September 2012. The experiment was arranged in descriptive comparative explanative method. Treatments of this experiment were Boron from boric acid (0, 500, 1000, 1500, and 2000 ppm). Boron 500 ppm on nursery plants of durian Monthong increases the flush growth and photosynthesis activity. Flush number, leaf number per flush, leaf number per plant, leaf area per flush, leaf area per plant, and photosynthesis activity score on nursery plants of durian Monthong that sprayed by 500 ppm Boron resulted higher value than 1000 ppm, 1500 ppm, 2000 ppm and 0 ppm Boron Key words : Boron, durian Monthong, flush, photosynthesis activity iii