PENDUGAAN AKSI GEN DAN DAYA WARIS KETAHANAN KAPAS TERHADAP Amrasca biguttula - MOCH. MACHFUD; E. SULISTYOWATI (Pusat Penelitian dan Pengembangan Perkebunan, 2009)
ABSTRAKAmrasca biguttula merupakan salah satu hama utama kapas yangmampu menurunkan hasil secara nyata. Penggunaan varietas tahan hamasecara genetik merupakan salah satu dari sekian metode pengendalianyang efektif untuk menurunkan kerusakan hama. Penelitian bertujuanuntuk mengetahui aktivitas kerja gen dan daya waris gen yang mengen-dalikan sifat ketahanan terhadap hama pengisap daun A. biguttula.Penelitian dilakukan di Karangploso, Kabupaten Malang, Jawa Timur daribulan Mei sampai Oktober 2006. Pengujian dilakukan terhadap 17genotipe yang terdiri dari (a) tiga varietas tetua jantan berbulu lebat yaituLRA 5166, SRT-1, dan Laxmi; (b) dua varietas tetua betina yangditingkatkan ketahanannya yaitu Kanesia-8 dan Kanesia-9; (c) enamgenotipe generasi F1 hasil persilangan tetua jantan dan betina tersebut diatas, dan d) enam genotipe generasi F2 yang merupakan keturunan darihasil persilangan F1. Percobaan disusun dalam rancangan acak kelompok(RAK), diulang 3 kali. Hasil penelitian menunjukkan bahwa tiga genotipeF1 dari pasangan persilangan Kanesia-8 x LRA 5166, Kanesia-9 x LRA5166, dan Kanesia-8 x Laxmi menunjukkan penampilan gen yangmengatur kelebatan bulu daun bersifat dominansi sebagian negatif.Sedangkan penampilan gen pada pasangan persilangan Kanesia-8 x SRT-1, Kanesia-9 x SRT-1, dan Kanesia-9 x Laxmi adalah dominansi sebagianpositif. Nilai heritabilitas dalam arti luas dari gen yang mengatur kelebatanbulu daun pada empat pasangan persilangan Kanesia-8 x SRT-1, Kanesia-9 x SRT-1, Kanesia-8 x Laxmi, dan Kanesia-9 x Laxmi adalah tinggi,sedangkan dua pasangan persilangan Kanesia-8 x LRA 5166 dan Kanesia-9 x LRA 5166 nilai heritabilitasnya sedang. Korelasi nyata terjadi antarajumlah bulu daun, populasi nimfa dan nilai JRI. Tingkat kehadiranpopulasi nimfa wereng dan nilai JRI sangat dipengaruhi oleh kerapatanbulu daun.Kata kunci : Gossypium hirsutum, Amrasca biguttula, kerapatan bulu,ketahanan, daya warisABSTRACTEstimation of Gene Action and Resistance Heritability ofCotton to Amrasca biguttulaAmrasca biguttula is one of main pests attacking cotton that causessignificant yield loss. The use of resistant varieties is genetically aneffective way to control the pest. An experiment was conducted to studythe activity and heritability of gene(s) responsible for controlling cropresistance to jassid, A. biguttula. The test involved 17 genotypes consistingof (a) three varieties with high trichome density as male parents i.e. LRA5166, SRT-1, and Laxmi; (b) two varieties to be improved their resistanceto jassid as female parents i.e. Kanesia-8 and Kanesia-9; (c) six genotypesof F1 generation resulted from crossing between male and female parents,and d) six genotypes of F2 generation resulted from selfing of genotypes.The test was arranged in randomized block design with three replications.Experimental result showed that the action of gene(s) responsible intrichome density or leaf pubescent of three F1 genotypes i.e. Kanesia-8 xLRA 5166, Kanesia-9 x LRA 5166, and Kanesia-8 x Laxmi were partlynegative dominance, whereas those of F1 genotypes of Kanesia-8 x SRT-1, Kanesia-9 x SRT-1, and Kanesia-9 x Laxmi were partly positivedominance. The heritability of that gene(s) in Kanesia-8 x SRT-1,Kanesia-9 x SRT-1, Kanesia-8 x Laxmi, and Kanesia-9 x Laxmicombinations were high, whereas those in Kanesia-8 x LRA 5166 andKanesia-9 x LRA 5166 combinations were medium. A significantcorrelation was observed between trichome density, nymph population,and JRI value, in which nymph population and JRI were significantlyinfluenced by trichome density.Key words : Gossypium hirsutum, Amrasca biguttula, gene action,heritability