RESPON VARIETAS JAGUNG TERHADAP PUPUK NITROGEN DI LAHAN SAWAH DAN LAHAN KERING

ABSTRACT Responses of Maize Variety towards Nitrogen in Irrigated Lowland and Upland. Nitrogen is a very important nutrient for growth and yield of maize, while its availability in the soil is not sufficient for the crops. The experiment to evaluate the response of maize cultivars to nitrogen was carried out in lowland irrigated and upland soil in Bantaeng District, South Sulawesi, from May to December 2009. Experiments were arranged in factorial randomized block design with two factors and three replications. Factor I were nine maize ciltivars, and factor II were two levels of nitrogen fertilizer. The results showed that cob yields, 1000-seed weights, and height of cob were affected significantly by site x variety x nitrogen fertilizer interaction. Therefore, to obtain the optimum performance of the characters, the specific combination of treatments was needed. The response pattern of maize cultivars to nitrogen was not similar in lowland irrigated compared to upland soil. Cultivar “Local B Kuning” and “X01904” showed the higher positive response in lowland irrigated, while cultivar “X02804” had the smallest negative response in upland soil. Based on cob yield, cultivar Bima-1 and “X01904” could be suggested to develop in lowland irrigated, while Bima 1, X02904, and X03604 were better for upland soil conditions. Keywords: Maize, nitrogen, lowland irrigated, uplandABSTRAK Hara nitrogen merupakan hara makro yang penting bagi pertumbuhan dan hasil tanaman jagung, sementara itu ketersediaan di dalam tanah tidak cukup bagi tanaman. Kajian untuk mengetahui respon sembilan varietas jagung terhadap peningkatan dosis pupuk nitrogen telah dilakukan di lahan sawah dan lahan kering Kabupaten Bantaeng, Sulawesi Selatan pada bulan Mei-Desember 2009. Percobaan ditata dalam rancangan acak kelompok pola faktorial dua faktor dengan tiga ulangan. Faktor I adalah sembilan varietas jagung dan faktor II dua dosis pupuk Nitrogen (200 dan 400 kg N/ha). Ukuran petak 3 m x 5 m, jarak tanam 75 cm x 20 cm, 2 biji/lubang. Hasil penelitian menunjukkan bahwa bobot tongkol, bobot 1000 biji dan tinggi letak tongkol jagung dipengaruhi oleh interaksi tiga faktor (lokasi x varietas x pupuk), sehingga untuk mendapatkan keragaan yang optimal untuk karakter tersebut membutuhkan kombinasi perlakuan lokasi, varietas dan pupuk N tertentu (spesifik lokasi). Pola respon varietas jagung terhadap pupuk N di lahan sawah berbeda dengan pola respon varietas terhadap pupuk N di lahan kering, di mana respon positif varietas terhadap pupuk N ditemukan di lahan sawah, tetapi respon negatif terdapat di lahan kering. Respon positif terbaik terhadap pupuk N di lahan sawah terdapat pada varietas Lokal B kuning dan X01904, sementara respon negative terkecil di lahan kering terdapat pada varietas X02804. Berdasarkan bobot tongkol, varietas Bima 1 dan X01904 layak dikembangkan di lahan sawah Kabupaten Bantaeng, dan varietas Bima 1, X02904, dan X03604 cukup prospektif untuk lahan kering Kabupaten Bantaeng, Sulawesi Selatan. Kata kunci: Jagung, pupuk nitrogen, lahan sawah, lahan kerin