PENGARUH POPULASI TANAMAN TERHADAP SIFAT AGRONOMIS SERTA KADAR Cl DAUN TEMBAKAU VIRGINIA RAJANGAN PADA TANAH VERTISOLS DI BOJONEGORO

Percobaan lapang telah dilakukan pada tanah vetisol di Kebun Percobaan Pekuwon, Bojonegoro, dimulai Mei sampai September 1996, untuk mempelajari pengaruh populasi tanaman tembakau terhadap sifat agronomis dan kadar Cl daun tanaman tembakau Virginia yang diolah dengan cara dirajang. Tinggi tempat dari lahan percobaan 13 m dpi, dan dengan tipe iklim D. Tanah bertekstur liat dengan 80% liat, 15% debu dan 5% pasir, 0.62% C-organik, 0.10% N, dan pH 8.20. Percobaan disusun dalam ancangan acak kelompok dengan 4 ulangan. Perlakuan terdiri dari enam laraf populasi tanaman tembakau (12 000; 18 000; 24 000; 36 000; 48 000, dan 60 000 tanaman per ha atau setara dengan 144, 216, 288, 432, 576, dan 720 tanaman per petak). Ukuran petak 12 m x 10 m. Dalam percobaan ini akan dipelajari pula pengaruh bentuk hasil (rajangan dan krosok) terhadap kadar Cl daun. Sepuluh tanaman per petak diolah secara lue-cuing di dalam oven mini, untuk dianalisis kadar Cl daunnya. Varietas tembakau adalah DB 101. Hasil dan indeks tanaman masih terus meningkat sampai populasi tetinggi, sedangkan mutu dan rendemen tidak terpengaruh oleh peningkatan populasi. Peningkatan populasi sebaliknya menurunkan ukuran daun, bobot tiap daun, tinggi tanaman, lingkar batang, dan jumlah daun yang dapat dipanen. Berdasar hasil, mutu dan mudahnya pengelolaan di lapang populasi yang optimal adalah 24 000 tanaman per ha, untuk tembakau Virginia rajangan di Bojonegoro. Peningkatan populasi hanya berpengaruh pada kadar Cl daun atas saja. Sedangkan bentuk hasil tembakau ajangan dan krosok tidak berpengaruh pada kadar Cl daun.Kata kunci: Nicotiana tabacum, tembakau. tembakau Virginia rajangan, populasi tanaman, vertisols, sifat agronomis, kadar Cl, bentuk olahan ABSTRACT Effect of plant population on agronomic characteristics and leaf Cl content of sliced Virginia tobacco grown in vertisols of BojonegoroThe expeiment was conducted in vetisol soil of Bojonegoro in 1996 to study the effect of plant population on agronomic characteistics and Cl content of sliced tobacco leaves. The experiment was site located 13 m above sea level, with D climatic type. The soil characteristics were clay texture with 80% clay, 15% silt and 5% sand, 0.62% C-organic, 0.10 % N, and pH 8.2. The treatment consisted of six plant populations (12.000 up to 60.000 plants per ha equal with 144, 216, 288, 432, 576, and 720 plants per plot) was arranged in a randomized block design, with four replications. Plot size was 12 m x 10 m. Plant population per plo( based on the six treatment levels. For Cl content analysis, 10 plants plot was also taken to be processed with lue-curing method in mini oven. Tobacco variety was DB 101. Yield and crop index increased steadily as plant population increased up to the highest plant population. However the increase in plant population decreased the size, weight, number of leaves, and plant height. While grade index, percentage of dry to fresh leaf yield and Cl content of lower and middle leaves were not affected by the increase in plant population. Base on yield, quality, and easier management, the recommended plant population was 24 000 plant per ha. The increase in plant population only affected the Cl content of upper leaves. The form of sliced and lue-cured tobacco leaves did not affect the Cl content of (he leaves.Key words : Nicotiana tabacum, tobacco, sliced Virginia tobacco, plant population vetisols, agronomic characteristic, Cl contcnl, product form