<![CDATA[SummaryAM fungal symbiosis increase the uptake of P in oil palm seedlings. However the optimum condition of symbiosis has to be determined to get higher benefit of AM fungal symbiosis. Optimization of the symbiosis Acaulospora tuberculata and Gigaspora margarita with oil palm seedling in acid soil was determined. An experiment was conducted in polybag sized 40 x 60 cm contained sterilized Cikopomayak soil. Three factors studied were AM fungal species (A. tuberculata, G. margarita), inoculant dose (0.0; 12.5; 25.0; and 37.5% w/w), and fertilizer rate (0; 25; 50; and 100% recommended dose) and each treatment replicated three times. The result showed that optimum growth reached on the inoculant addition of 36% (w/w) in the form of infected roots, hypha, and spores and fertilizer dose of 25% for A. tuberculata, while for G. margarita was 40% (w/w) inoculant and 26% fertilizer. Efectivity of fertilizer and P uptake of oil palm seedling were significantly increased with AM fungi inoculation. P uptake of oil palm seedling inoculated with A. tuberculata increase. RingkasanSimbiosis cendawan mikoriza arbuskula (CMA) dapat meningkatkan serapan P pada pembibitan kelapa sawit. Namun, untuk mendapatkan keuntungan simbiosis yang tinggi perlu diketahui kondisi optimum simbiosis. Simbiosis CMA dengan tanaman sangat dipengaruhi tingkat hara dan dosis inokulum. Percobaan dilakukan dalam polibag berukuran 40 x 60 cm berisi tanah Cikopomayak steril. Tiga faktor yang diuji ialah spesies CMA (A. tuberculata, G. margarita), dosis inokulum campuran (0,0; 12,5; 25,0; dan 37,5% b/b), dosis pupuk (0; 25; 50; dan 100% dosis rekomendasi) dan masing masing perlakuan diulang tiga kali. Hasil percobaan menunjukkan bahwa pertumbuhan optimum dicapai pada pemberian inokulum berupa akar terinfeksi, hifa, dan spora 36% (b/b) dan pupuk 25% untuk A. tuberculata, sedangkan untuk G. margarita ialah 40% (b/b) inokulum dan pupuk 26%. Keefektifan pupuk dan serapan P meningkat secara nyata dengan inokulasi CMA]]>
