ISSN 1411 – 0067 Jurnal Ilmu-Ilmu Pertanian Indonesia. Volume 8, No. 1, 2006, Hlm. 1 - 5 1 INHERITANCE OF TRAITS ASSOCIATED WITH DROUGHT RESISTANCE IN COWPEA PEWARISAN KARAKTER YANG TERKAIT DENGAN KETAHANAN TERHADAP KEKERINGAN PADA KACANG TUNGGAK M. Chozin 1 , J.O. Garner 2 , and C.E. Watson 2 1 Agicultural Faculty, University of Bengkulu 2 Department of Plant and Soil Sciences Mississippi State University mchozin@hotmail.com ABSTRACT The genetic of traits related to drought-resistance in cowpea was studied using generation mean analysis. The two contrasting drought-resistance genotypes were crossed to generate F1, F2, F3, BC1, BC2, BC1S1, and BC2S1populations which were imposed to a controlled water deficit conditions from flowering to early pod formation. The analyses were performed on stem diameter, delayed leaf senescence, and leaf temperature which were identified in earlier study as good discriminators in discerning genotypes for drought-resistance. The resistant genotype was characterized by higher delayed leaf senescence, larger stem diameter, and lower leaf temperature . The means indicated that delayed leaf senescence was controlled by partial dominant gene(s) dan segregated toward resistance. Heterotic effect toward susceptibility was found on stem diameter but recombination and segregation had seemed to bring about a reversed direction. Partial dominant gene(s) also played an important role in governing leaf temperature toward susceptibility. The Hayman’s generation mean analysis suggested that additive effect was important in controlling the three traits. The dominant and epistatic (additive-additive and additive dominant) effects were significant on stem diameter, whereas additive-dominant effect was the only additional effect for leaf temperature, beside the additive effect. Key words : cowpea, inheritance, d rought-resistance ABSTRAK Sifat genetik dari karakter yang terkait dengan resistensi terhadap kekeringan pada kacang tunggak dipelajari dengan analisis rataan generasi. Dua genotipe yang berbeda resistensinya disilangkan untuk menghasilkan populasi F1, F2, F3, BC1, BC2, BC1S1, dan BC2S1 yang kemudian dihadapkan pada kondisi kekurangan air pada fase pembungaan hingga awal pengisian polong. Analisis dilakukan pada karakter penundaan penuaan daun, diameter batang, dan suhu daun, yang sebelum diidentifakasi sebagai karakter yang dapat digunakan untuk membedakan genotipe resisten dan genotipe peka kekeringan. Genotipe resisten dicirikan dengan skor penunadaan penuaan daun yang lebih tinggi, diameter batang lebih besar, dan suhu daun lebih rendah dibanding genotipe peka. Nilai rataan menunjukkan bahwa penundaan penuaan daun dikendalikan oleh gen dominan parsial dan bersegregasi ke arah resisten. Efek heterotik ke arah peka dijumpai pada diameter batang tetapi cenderung berbalik ke arah resisten jika mengalami rekombinasi atau segregasi. Gen dominant parsial juga mempunyai peran penting dalam mengatur suhu daun ke arah peka. Analisis rataan generasi Hayman menunjukkan bahwa efek aditif mempunyai peran penting dalam mengendalikan ke tiga karakter. Efek dominan dan epistasis (aditif-aditif dan aditif-dominan) merupakan efek tambahan yang nyata pada diameter batang, sedangkan efek aditif-dominan merupakan satu- satunya efek tambahan pada suhu daun selain efek aditif. Kata kunci : kacang tunggak, pewarisan, resisten kekeringan