Pengembangan kedelai hitam diarahkan ke dataran rendah dan dataran menengah. Kendala di dataran menengah antara lain berkaitan dengan suhu, tingkat kesuburan tanah rendah dan kersediaan air pengairan, tanaman dapat mengalami kelebihan air atau kekeringan. Penelitian ini bertujuan untuk mengetahui pengaruh GA3 dan pupuk P terhadap pertumbuhan dan hasil kedelai hitam dalam kondisi kekurangan dan kelebihan air di dataran rendah dan dataran menengah. Penelitian pot di rumah kaca dan penelitian lapangan di dataran rendah dilaksanakan di KP4 UGM di Kalitirto, Berbah, Sleman, Yogyakarta. Penelitian di dataran menengah di Pakembinangun, Pakem, Sleman, Yogakarta. Penelitian pot dilaksanakan mulai bulan Februari - Juli 2006. Penelitian lapangan di dataran rendah dan menengah dilaksanakan bersamaan mulai bulan Mei - Agustus 2007. Penelitian pot menggunakan Rancangan faktorial 3 x 3 x 3 x 2 yang disusun dalam Rancangan Acak Lengkap (Completely Randomized Design) dengan 3 ulangan. Faktor pertama adalah lengas tanah terdiri atas 3 aras: 1. lengas tanah 50% jenuh air dari kapasitas lapangan 2. lengas tanah kapasitas lapangan 3. lengas tanah 50% kering dari kapasitas lapangan. Faktor kedua adalah konsentrasi GA3 terdiri atas 3 konsentrasi: 1. GA3 0 ppm; 2. GA3 100 ppm; 3. GA3 200 ppm. Faktor ketiga adalah pupuk SP 36 terdiri atas 3 takaran: 1. SP 36 - 0 kg/ha; 2. SP 36 - 75 kg/ha; 3. SP 36 - 150 kg/ha. Faktor keempat adalah varietas kedelai terdiri 2 varietas: 1. kedelai hitam Mallika dan 2. kedelai kuning Baluran. Penelitian lapangan di dataran rendah dan menengah menggunakan kedelai hitam varietas Mallika dan Rancangan Faktorial 3 x 3 x 3 dengan 3 ulangan, disusun dalam Rancangan Acak Kelompok Lengkap. Faktor pertama adalah lengas tanah terdiri atas 3 aras: 1. lengas tanah 50% jenuh air dari kapasitas lapangan; 2. lengas tanah kapasitas lapangan; 3. lengas tanah kering 50% dari kapasitas lapangan. Faktor kedua adalah GA3 terdiri atas 3 konsentrasi: 1. GA3 0 ppm; 2. GA3 100 ppm; 3. GA3 200 ppmi. Faktor ketiga adalah pupuk SP 36 terdiri atas 3 takaran: 1. SP 36 - 0 kg/ha; 2. SP 36 - 75 kg/ha; 3. SP 36 - 150 kg/ha. Hasil penelitian menunjukkan bahwa penanaman kedelai hitam Mallika dengan GA3 100 ppm dan pupuk SP 36 - 75 kg/ha dalam kondisi kelebihan air di dataran rendah maupun menengah dapat meningkatkan anatomi, fisiologi, pertumbuhan dan hasil sebesar 25,91% dari 1,44 ton/ha menjadi 1,79 ton/ha dibandingkan dengan tanpa GA3 dan SP 36. Kedelai hitam yang ditanam dalam kondisi kekurangan air dengan GA3 100 ppm dan pupuk SP 36 - 75 kg/ha di dataran rendah maupun menengah dapat meningkatkan anatomi, fisiologi, pertumbuhan dan hasil sebesar 23,53% dari 1,39 ton/ha menjadi 1,65 ton/ha dibandingkan dengan tanpa GA3 dan SP 36

The soybean development is directed to the lowlands and medium lands, the main obstacle to the development of soybeans in medium lands related to, among others, the temperature, low soil fertility and limited availability of irrigation, plants may experience excess water or shortage of water . This study aims at determining the effect of GA3 and Fosfor fertilizers on growth and yield of black soybeans in the conditions of excess water or shortage of water in the lowlands and medium lands. The pot experiments in the green house and the field experiments in the low lands were conducted in Kalitirto, Berbah, Sleman, Yogyakarta, from February - July 2006. Field experiments in the medium lands were conducted in Pakembinangun, Pakem, Sleman, Yogyakarta. The pot experiment was conducted from February until July 2006. The field experiment was done from May until August 2007. The pot experiments using factorial design 3 x 3 x 3 x 2 which were arranged in the Completely Randomized Design with 3 replications. The first factor was the soil humidity which consisted of three levels, namely: 1. The ecxess water (50% of water lodging); 2. field capacity of soil moisture ; 3. Shortage of water (50% of water stress). The second factor was the concentration of GA3 which consisted of three levels, namely: 1. GA3 of 0 ppm; 2. GA3 of 100 ppm; 3. GA3 of 200 ppm. The third factor was the SP 36 fertilizer consisted of three levels, namely: 1. SP 36-0 kg/ha; 2. SP 36-75 kg/ha; 3. SP 36-150 kg/ha. The fourth factor was consisted of two soybean varieties, namely: 1. black soybean Mallika variety and 2. yellow soybean Baluran variety. The field experiment in the lowlands and medium lands using black soybean Mallika variety and Factorial Design 3 x 3 x 3 with 3 replications, arranged in the Randomized Complete Block Design. The first factor was the soil humidity which consisted of 3 levels: 1. The ecxess water (50% of water lodging); 2. field capacity of soil moisture ; 3. Shortage of water (50% of water stress). The second factor was the concentration of GA3 which consisted of three levels, namely: 1. GA3 of 0 ppm; 2. GA3 of 100 ppm; 3. GA3 of 200 ppm. The third factor was the SP-36 fertilizer consisted of 3 levels: 1. SP 36-0 kg/ha; 2. SP 36-75 kg/ha; 3. SP 36-150 kg/ha. The results of this experiments showed that Mallika black soybean planted in the lowlands and medium lands, on the excess water condition with 100 ppm GA3 and fertilizer SP 36 of 75 kg/ha increased the anatomis, fisiologis, growth and average yield by 25.91% from 1.44 tons/ha to 1.79 tons/ha compared with the one without GA3 and SP 36 fertilizer. The black soybeans which were planted in shortage of water conditions in the lowlands and medium lands, with 100 ppm GA3 and fertilizer SP 36 of 75 kg/ha increased the anatomis, fisiologis, growth and average yield by 23.53% from 1.39 tons/ha to 1.65 tons/ha, compared with no GA3 and SP 36 fertilizer

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