Effect of water stress on the production and quality of Sonchus arvensis L.

anglais. Study on water stress in Sonchus arvensis L. was conducted to improve the quality and production of leaves. Pot experiment was conducted at green house Bogor Research Institute for Spice and Medicinal Crops from July to November 1996, with 7 kg latosol dry soil of Cimanggu Bogor per pot. Randomized block design with four replications were used. Eight treatments of water stress and casting were applied i.e.: (1) 100 percent field capacity (FC) no casting, (2) 100 percent FC + casting, (3) 80 percent FC + casting with water stress started at 30 days after planting (dap), (4) 60 percent FC + casting with water stress started at 30 dap, (5) 40 percent FC + casting with water stress started at 30 dap, (6) 80 percent FC + casting with water stress started at 30 dap, (7) 60 percent FC + casting with water stress started at 50 dap, (8) 40 percent FC + casting with water stress started at 50 dap. Results showed that chlorophyll content, leaf area, fresh and dry weight of leaves decreased at a water stress of 60 percent FC started at 30 dap. The higher the water stress, the lower the measurement of those parameters, but the higher the content of K and Na. The highest yield of fresh and dry leaves, respectively 53.22 and 4.58 g/plant was produced by the plants treated in 100 percent FC + casting. The plant treated in 40 percent FC started at 30 dap resulted in the highest quality of simplisia indicated by the highest content of K (8.2 percent) and Na (0.227 percent) with the treatment, Kand Na content increased by 13.6 and 95.7 respectively and the dry weight of simplisia decreased by 62.9 percent

inconnu. Penelitian cekaman air pada tanaman tempuyung bertujuan untuk meningkatkan mutu dan produksi telah dilakukan di rumah kaca Balittro Bogor dari bulan Juli sampai November 1996. Percobaan pot menggunakan tanah kering angin jenis Latosol Cimanggu Bogor, sebanyak 7 kg/pot dengan menggunakan rancangan acak kelompok empat ulangan. Sebanyak delapan perlakuan cekaman air dan kasting yaitu; (1) 100 persen kapasitas lapang (KL) tanpa kasting, (2) 100 persen KL + kasting, (3) 80 persen KL + kasting dengan cekaman air dimulai 30 hari setelah tanam (HST), (4) 60 persen KL + kasting dengan cekaman air dimulai 30 HST, (5) 40 persen KL + kasting dengan cekaman air dimulai 30 HST, (6) 80 persen KL + kasting dengan cekaman air dimulai 50 HST, (7) 60 persen KL + kasting dengan cekaman air dimulai 50 HST, (8) 40 persen KL + kasting dengan cekaman air dimulai 50 HST. Hasil penelitian menunjukkan bahwa kandungan khlorofil daun, luas daun, bobot segar dan kering daun menurun pada perlakuan cekaman air 60 persen diberikan 30 HST, semakin besar cekaman air semakin besar penurunannya, tetapi kadar K dan Na daun meningkat sehingga mutu daun semakin tinggi. Produksi simplisia tertinggi (bobot segar dan kering daun) masing-masing 53.22 dan 4.58 g/ tanaman pada perlakuan 100 persen KL + kasting. Mutu simplisia tertinggi berdasarkan kadar K (8.2 persen) dan Na (0.227 persen) pada cekaman air 40 persen KL dimulai pada 30 HST, masing-masing meningkat 13.6 persen dan 95.7 persen yang diikuti dengan penurunan bobot kering simplisia sebesar 62.9 persen