GATRA FISIOLOGIS DAN AGRONOMIS PADI DENGAN PENGAIRAN SISTEM GENANGAN DALAM PARIT DI INCEPTISOL

Ir. Syamsuddin, M.Sc., Prof. Dr. Ir. Didik Indradewa, Dip. Agr. St.,

2013 | Disertasi | S3 Agronomi

Sumber bahan pangan utama penduduk Indonesia dari padi sawah. Padi sawah merupakan pengguna air irigasi terbesar dan tergolong sangat boros. Ketersediaan sumberdaya air untuk irigasi semakin terbatas. Penelitian “Gatra fisiologis dan agronomis padi dengan pengairan sistem genangan dalam parit di Inceptisol dilaksanakan dalam 3 tahap percobaan. Percobaan pertama untuk mendapatkan kultivar yang tanggap terhadap pengairan sistem genangan dalam parit (SGDP) dan lebar bedengan optimun. Percobaan kedua untuk mendapatkan karakter fisiologis dan agronomis kultivar yang tanggap pengairan SGDP dan jarak tanam yang optimal. Percobaan ketiga untuk mendapatkan jeluk muka air genangan pada parit optimal pada setiap fase pertumbuhan, kebutuhan air irigasi serta efisiensinya. Penelitian berlokasi di Sidoarum, kecamatan Godean, kabupaten Sleman Yogyakarta. Pelaksanaan penelitian berlangsung pada April 2010 sampai bulan Maret 2012. Lokasi penelitian merupakan wilayah pengembangan padi sawah beririgasi teknis. Jenis tanah lahan penelitian adalah Inceptisol. Hasil penelitian menunjukkan bahwa dari penapisan 26 kultivar dan galur padi sawah, Cimelati merupakan kultivar yang sangat tanggap dan Sarinah merupakan kultivar yang agak tanggap. Potensi hasil kedua kultivar tersebut masing-masing 25,02 dan 21,46 g/rumpun. Lebar bedengan optimal adalah 4 m dengan parit pada kedua sisi bedengan. Karakter dan fisiologis agronomis kultivar tanggap yang meningkat secara nyata dengan pengairan SGDP dibandingkan cara sawah adalah ILD, Kadar klorofil (a, b, total), kadar prolin, LPT, berat kering tajuk, anakan maksimun, anakan produktif, dan biji per rumpun. Karakter yang menurun secara nyata adalah konduktivitas stomata, laju transpirasi, laju fotosintesis, LAB, LPR, lebar bukaan stomata, KAN, tinggi tanaman, persentase anakan produktif, panjang malai, jumlah biji per malai, persentase gabah isi, dan berat biji. Karakter yang tidak mengalami perubahan adalah sekapan cahaya, BDK, kehijauan daun, kerapatan stomata daun, kadar CO2 sel daun, suhu udara dipermukaan daun, suhu dan kelembapan daun, dan hasil gabah per rumpun. Karakter yang memberikan kontribusi terbesar terhadap berat kering adalah LPT yaitu sebesar 92,82%, kemudian diikuti oleh laju transpirasi sebesar 15,66%, kadar prolin sebesar 11,15%, dan kadar klorofil daun sebesar 9,66%. Jarak tanam yang optimal adalah 20 x 12,5 : 40 cm (legowo). Jeluk muka air 20 cm optimun untuk pertumbuhan fase vegetatif. Pada fase generatif diperlukan kadar lengas yang lebih tinggi dari kapasitas lapangan atau mendekati kadar lengas jenuh. Jeluk muka air genangan pada parit dari permukaan bedengan yang optimum adalah 0 cm saat pertumbuhan awal (0 - 21 hst) kemudian 20 cm saat fase vegetatif aktif (21 - 60 hst), 0 cm saat fase inisiasi malai (61 - 90 hst), dan 20 cm saat fase berbunga sampai pengisian biji pada malai telah penuh (91 - 110 hst) dengan hasil gabah 8,36 t/ha. Kebutuhan air irigasinya sebesar 6.371 m3/musim, reduksi air irigasi dari cara sawah sebesar 47,39%, produktivitas air irigasinya (PAI) sebesar 1,31 g gabah/kg air, efisiensi evapotranspirasinya sebesar 3,41 g gabah/kg air. Hasil gabah cara sawah sebesar 8,59 t/ha.

The main staple food source of Indonesia’s population is rice. Rice field require large amount of irrigation water. Rice is classified as plant with waste of water. The availability of water resource for irrigation has become limited. Research on “Physiological and Agronomical Aspects of Rice under Saturated Soil Culture Irrigation System at Inceptisol” was conducted in 3 stages of experiments. The first experiment was carried out to identified cultivar having good response to the satutrated soil culture (SSC) system and optimal bed width. The second experiment was to tudy the physiological and agronomical characters of cultivars having good response to SSC irrigation system and optimal planting distance. While for the third, the experiment was done to study water surface depth level in optimal furrow within each growth phase, irrigation water need, and its efficiency as well. The research was located at Sidoarum, district Godean, regency Sleman, Yogyakarta. It was held from April 2010 up to March 2012. Location of the study was region of rice field development with technical irrigation. The results showed that among 26 cultivars of rice, the “Cimelati” was the most responsive cultivar and the “Sarinah” has less responsive. Potential yield of Cimelati and Sarinah were 25,02 and 21,46 g/plant. The optimal beds width was 4 m with furrow in both bed sides. Physiological and agronomical characters of rice showed the increasing values by SSC irrigation system comparing to the rice field involved leaf area index (LAI), chlorophyll content (a, b, total), prolin content, crop growth rate (CGR), dry shoot weight, maximum seed, productive seed and grain per plant. The decreased characters values involved stomata conductivity, transpiration rate, photosynthesis rate, net assimilation rate (NAR), relative growth rate (RGR), stomata opening width, relative water content (RWC), plant height, productive tiller percentage, panicle length, number of grain per panicle, grain content percentage and grain weight. While for non-changes characters, they involved lighting capture, leaf weight specific, leaf greenness, leaf stomata density, CO2 content of leaf cells, air temperature in leaf surface, leaf temperature and humidity, and grains weight per plant. Characters with largest contribution to the dry weight was CGR, 92,82% followed by transpiration rate 15.66%, proline content 11.15%, and leaf chlorophyll 9.66%. The optimal planting distance was 20 x 12,5 : 40 cm (as legowo). The water surface depth of furrow based on beds surface optimum for vegetative growth phase. In the generative phase required moisture levels higher than or close to field capacity moisture saturation levels. The optimal water surface depth of furrow based on beds surface was 0 cm at initial stage of growth (0 - 21 days after planting), and then 20 cm at active vegetative phase (21 - 60 days after planting), 0 cm for panicle initiation phase (61 - 90 days after planting), and 20 cm for flowering phase till full grain content (91 - 110 days) with 8,36 t/ha for un-hulled rice production. The need of irrigation water was 6.371 m3/ha/season, irrigation water reduction based on rice field technique was 47.39%, productivity of irrigation water was 1.31 g grain/kg of water, evapo-transpiration efficiency 3.41 g grain/kg water. The yield of rice with rice field technique was 8.59 t/ha.

Kata Kunci : Genangan dalam parit, kultivar tanggap, karakter fisiologis dan agronomis fisiologis, lebar bedengan, jarak tanam, jeluk muka air, efisiensi irigasi, hasil gabah.