Gatra agronomis dan fisiologis pengaruh genangan dalam parit pada tanaman kedelai

INDRADEWA, Didik, Promotor Prof.Dr.Ir. Soemartono Sastrowinoto

2002 | Disertasi | S3 Ilmu Pertanian

Genangan dalam parit dibuktikan oleh banyak peneliti dapat meningkatkan hasil kedelai di lapangan sampai 20 % dengan jeluk muka air 15 cm. Dua percobaan pot, empat percobaan lapangan dan satu petak percontohan dilakukan dengan tuj uan untuk mendapatkan genangan dalam parit yang membuat lengas tanah optimum sehingga diperoleh hasil biji maksimum serta penjelasan mekanisme peningkatan hasil yang terjadi. Percobaan pot dilakukan di Kebun Percobaan Jurusan Budidaya Pertanian Fakultas Pertanian UGM Yogyakarta, percobaan lapangan dilakukan di Kabupaten Sleman dan Klaten serta petak percontohan di Kabupaten Klaten antara tahun 1990 dan 1999. Penelitian dilakukan untuk mempelajari pengaruh interaksi jeluk muka air dengan kultivar. genangan dalam parit bergilir dengan jenis tanah, pengaruh lebar petak dan fase pertumbuhan yang tanggap. Pengamatan dilakukan terhadap status air tanah dan tanaman, proses iisiologis. pertumbuhan , hasil dan komponen hasil. Hasil penelitian menunjukkan bahwa dengan genangan dalam parit lengas tersedia optimum sekitar kapasitas lapangan sehingga dapat memacu proses fisiologis, pertumbuhan dan hasil kedelai. Peningkatan hasil antara 70 dan 150 % dari pengairan luapan antara 1,12 dan 1,59 t ha-' menjadi 2,12 sampai 2,81 t ha" dengan genangan dalam parit. Kultivar Petek yang lebih tahan genangan, lebih tanggap terhadap genangan dalam parit dibanding kultivar Wilis. Jeluk muka air optimum untuk kultivar Petek 15 sampai 20 cm dan kultivar Wilis 20 sampai 25 cm. Dengan jeluk muka air 22,5 cm. lebar bedengan optimum genangan dalam parit di tanah Regosol antara 3 dan 4 m. Penerapan genangan dalam parit selarna musim kemarau hanya pada fase berbunga tidak menurunkan hasil secara nyata dibanding penerapan terus menerus. Pada musim hujan genangan dalam parit tidak meningkatkan hasil dan penerapan pada fase vegetatif memberi pengaruh paling buruk. Genangan dalam parit dapat diterapkan di tanah Regosol, tetapi tidak layak diterapkan di tanah Grumusol sesudah padi sawah. Genangan dalam parit bergilir tujuh hari sckali tidak dapat meningkatkan hasil kedelai, demikian juga penerapan genangan dalam parit pada tanaman yang tumbuh terlalu lebat

Saturated soil culture increases soybean seed yield in the field up to 20 % under depth of water 15 cm below soil surface. Two pot experiments, four field experiments and one demonstration plot were conducted to find out a saturated soil culture technique which was resulted in optimal soil moisture and maximal seed yield foI1owed by explanation mechanism of physiological processes occurred. The pot experiments were conducted at Research Station of Department of Agronomy, Faculty of Agriculture, GMU, Yogyakurta. Field experiments were conducted at Sleman and Klaten Regencies and demonstration plot was conducted at Klaten Regency from 1990 to 1999. The experiments were conducted to study interaction effects between depth of water surfaces with soybean cultivars. between alternate saturated soil culture with soil great groups, the effect of bed’s width and responsive growth stages. Observations were done on soil moistwe and plant water status. physiological proces, growth, yield and yield components of soybean. Result of the experiments showed that under saturated soil culture, soil moisture supplied at optimal condition around field capacity, resulted in higher physiological processes, growth and yield of soybean. The yield increase was around 70 up to 150 %>om 1.12-1.59 t ha-’ under flood irrigation up to 2.12-2.81 t ha” under saturated soil culture. Petek a more flooding tolerant cultivar had better response to saturated soil culture than Wilis a more tolerant to drier condition soybean cultivar. The optimal depth of water surface for cv. Petek was I5 to 20 cm and cv. Wilis 20 to 25 cm. With water table 22.5 cm below soil szsrface, the optimal width of bed in Regosol soil was 3 to 4 m. Application of saturated soil culture during dry season merely on flowering stage did not reduce seed yield significantly compared to the application continuously in all stages of growth. During rainy season saturated soil culture did not increase seed yield and application on vegetative stage gave the worst result. Saturated soil culture can be applied on Regosol soil but was not appropriate on Grumusol soil after rice. Alternate saturated soil culture did not increase soybean seed yield, as well as application of saturated soil culture on plant that grew vigorously

Kata Kunci : Tanaman Kedelai,Genangan Parit,Gatra Ergonomis dan Fisiologi