Seleksi galur mutan sorgum [Sorghum bicolor (L.) Moench] untuk produktivitas biji dan bioetanol tinggi di tanah masam melalui pendekatan participatory plant breeding

Abstract

Sorgum adalah salah satu tanaman unggul yang dapat dikembangkan sebagai bahan pangan maupun energi, karena kedua komoditi tersebut dapat diintegrasikan proses produksinya dalam satu dimensi waktu dan ruang. Sorgum sangat toleran terhadap kekeringan, dan sangat sesuai dikembangkan di lahan kering Indonesia. Masalahnya adalah lahan kering tersebut banyak didominasi tanah masam dengan toksisitas Al yang dapat menurunkan produktivitas tanaman. Program pemuliaan tanaman partisipatif dapat digunakan untuk mendapatkan tanaman yang adaptif di lahan marjinal dan dikehendaki oleh petani. Tujuan utama penelitian ini adalah mengembangkan varietas sorgum toleran tanah masam dengan produktivitas biji dan atau bioetanol tinggi. Tujuan khususnya adalah (1) memperoleh informasi tentang adaptasi tanaman sorgum di tanah masam dan mendapatkan galur mutan toleran tanah masam dengan produktivitas tinggi, (2) mendapatkan karakter seleksi galur mutan sorgum yang sesuai dengan preferensi petani, dan kesesuaian pilihan galur mutan sorgum antara petani dan peneliti, dan (3) mengidentifikasi galur mutan yang memiliki potensi hasil baik biji maupun bioetanol yang lebih tinggi dari varietas yang sudah dikembangkan. Seleksi galur mutan sorgum dengan keragaman genetik tinggi di tanah masam melalui pendekatan Participatory Plant Breeding adalah cara untuk menjawab tujuan tersebut. Keragaman genetik diperoleh melalui teknik mutasi fisika dengan radiasi sinar Gamma yang telah dilakukan Pusat Aplikasi Teknologi Isotop dan Radiasi, Badan Tenaga Nuklir Nasional. Program seleksi pada penelitian ini disusun dalam tiga percobaan, yaitu (1) evaluasi galur mutan sorgum di tanah masam, (2) participatory varietal selection, dan (3) uji daya hasil pendahuluan di tanah masam.

Sorghum is one of high value commodities for food and energy security, because two commodities could be cultivated integratedly in one time and space. Sorghum is drought tolerance plant and suitable to be developed in Indonesia dry lands. The major problem of dry land in Indonesia is predominance of acid soil with Al toxicity. Participatory plant breeding program could be introduced in marginal land to improve adoption of the selected lines. The objective of this research was to develop sorghum variety tolerant to acid soil with high productivity of grain and bioethanol through Participatory Plant Breeding approaches. This research consisted of three stages, i.e: (1) evaluation of sorghum mutant lines in acid soil, (2) participatory varietal selection of sorghum mutant lines in acid soil, and (3) preliminary yield trial of selected lines in acid soil. Evaluation of sorghum mutant lines in acid soil was conducted by screening 61 mutant lines developed through gamma irradiation. The selection was conducted in an augmented design in Central-Lampung. Fiveteen lines selected from the screening in acid soil was used in a participatory varietal selection conducted in four different regions in Lampung in mother and baby trials. The prelimenary yield trial was conducted in a randomized complete block design experiment with 24 sorghum lines in three replications in East-Lampung. The results from the screening in acid soil showed that sorghum mutant lines ZH30-29-07, ZH30-30- 07, and ZH30-35-07 were tolerant in acid soil with high grain productivity and mutant lines PSj-60-05, ZH30-35-07, ZH30-29-07, and PSj-96-05 showed high ethanol productivity. The result of the participatory varietal selection showed that there were differences in preference among farmers in one location or between locations to mutant line selection traits, which led to differences in selected lines. Farmers preferred traits were resistance to loging, short maturity, good performance and high panicle weight. Famers selected ZH30-29-07, ZH30-30- 07, and ZH30-35-07 which have resistance to loging and good performance and high panicle weight, and selected B-76 and B-92 mutant line for ideal plant height and short maturity. There were similarity in selected lines between reseachers and farmers in PVS. The similar selection were ZH30-29-07, ZH30- 30-07, dan ZH30-35-07. This result showed that farmers have indigenous knowledge could to used for plant beeding program. Sorghum mutant lines i.e GH-ZB43-07, PSj-95-05, ZH30-29-07, and ZH30-30-07 showed highest grain yield, and ZH30-35-07, BR-ZH30-06-07, and PSj-95-05 showed highest ethanol production in the yield trial compared to national varieties. Mutant line PSj-95- 05 was both highest in grain and ethanol production.