Pengaruh cekaman kekeringan terhadap pertumbuhan tanaman jarak pagar (Jantropha curcas L.) asal biji dan stek di lahan pasir pantai

RAHARJO, Krisantus Tri Pambudi, Prof. Dr. Ir. Didik Indradewa

2009 | Tesis | S2 Agronomi

kemarau dapat menyebabkan cekaman kekeringan pada tanaman tahunan. Kekeringan dapat menyebabkan pertumbuhan yang berbeda pada bahan tanam asal stek dan biji. Suatu percobaan lapangan dilaksanakan untuk mempelajari pengaruh cekaman kekeringan terhadap pertumbuhan jarak pagar asal biji dan stek di Kebun Percobaan Fakultas Pertanian Universitas Gadjah Mada, Yogyakarta yang berlokasi di Desa Keburuhan, Kabupaten Purworejo, Jawa Tengah dari bulan Maret sampai Oktober 2008. Percobaan menerapkan rancangan acak kelompok lengkap 2 faktor dengan tiga ulangan. Faktor pertama adalah tanaman asal biji dan stek, sedangkan faktor kedua yaitu tingkat penyiraman 100, 60 dan 10% volume yang digunakan untuk mencapai kapasitas lapangan. Hasil penelitian menunjukkan bahwa tanaman jarak asal biji lebih tahan kering dan tumbuh lebih baik, sebaran perkaran lebih dalam, kandungan air nisbi, potensial air jaringan, lebar bukaan stomata, laju transpirasi serta konduktansi stomata lebih tinggi, sedangkan kandungan prolin lebih rendah. Selanjutnya, menghasilkan laju asimilasi bersih, bobot kering total, diameter batang, serta luas daun lebih tinggi, sedangkan rasio akar/tajuk lebih rendah, dibanding tanaman asal stek

Water deficit often occurs at costal sandy land particularly in dry season. This condition may cause drought stress to perennial crops having different root distribution patterns due to different in source of seedling materials i.e. from cuttings and seeds. A field experiment was carried to study the effect of drought on growth of physic nut derived from cutting and seed propagations on the experimental station of the Faculty of Agricultures, Gadjah Mada University, located at Keburuhan, Purworejo district, Central of Java, from March until October 2008. The experiment used a randomized complete block design with two factors and three replications. The first factor was source of seedlings, derived from cutting and seed propagations, and the second factor was watering with volume of water 100, 60, and 10% water volume at field capacity. The result of experiment shows that the growth of plant derived from seed was resistance to drought stress and better than from cutting, root distributions deeper, relative water contents, plant water potential, stomatal closure, transpiration rate, was higher while proline contents was lower. Furthermore, nett assimilation rate, dry matter, stem diameter, leaf area was higher, while root/shoot ratio was lower than from cuttings.

Kata Kunci : Cekaman kekeringan,Stek,Biji,Sebaran perakaran,Jarak pagar, drought stress, cutting, seeds, root distribution, physic nut