Microbial Inoculation Improves Growth of Oil Palm Plants (Elaeis guineensis Jacq.)

Abstract

Introduction of diazotrophic rhizobacteria to oil palm tissues during the in vitro micropropagation process establishes an early associative interaction between the plant cells and bacteria. In the association, the diazotrophs provide the host plants with phytohormones and fixed nitrogen. This study was conducted to observe growth of bacterised tissue cultured oil palm plants under ex vitro conditions after 280 days of growth. Root dry weight, shoot dry weight, root volume, bacterial colonisation, leaf protein and chlorophyll content of the host plants were observed. The results revealed that the inocula successfully colonised roots of the host plants. Plants inoculated with Acetobacter diazotrophicus (R12) had more root dry weight and volume than plants inoculated with Azospirillum brasilense (Sp7). Leaf protein and chlorophyll content were higher in the bacterised plants compared to Control 2 plants (inoculated with killed Sp7). These results suggest that the diazotrophs successfully improved the growth of the host plant (oil palm) and minimised the amount of N fertiliser necessary for growth.

Pengenalan rhizobakteria diazotrofik kepada tisu kelapa sawit ketika proses mikropropagasi secara in vitro membolehkan wujud interaksi asosiatif awal di antara sel tumbuhan dan bakteria. Di dalam hubungan asosiatif ini, diazotrof membekalkan tumbuhan perumah dengan fitohormon dan nitrogen terikat. Kajian ini dijalankan untuk menilai pertumbuhan tisu kultur kelapa sawit yang sedia dikolonisasi oleh bakteria (bacterised) dalam keadaan ex vitro selepas 280 hari pertumbuhan. Berat kering akar, berat kering pucuk, isipadu akar, kolonisasi bakteria dan kandungan protein serta klorofil daun tumbuhan perumah telah diperhatikan. Keputusan menunjukkan bahawa inokula telah berjaya mengkolonisasi akar tumbuhan perumah tersebut. Tumbuhan yang telah diinokulasi dengan Acetobacter diazotrophicus (R12) mempunyai lebih berat kering akar dan isipadu berbanding tumbuhan diinokulasi oleh Azospirillum brasilense (Sp7). Kandungan protein dan klorofil daun adalah lebih tinggi bagi tumbuhan yang telah diinokulasi (bacterised) berbanding tumbuhan Kawalan 2 (diinokulasi dengan Sp7 mati). Keputusan ini mencadangkan bahawa diazotrof tersebut berjaya meningkatkan pertumbuhan perumah (kelapa sawit) dan mengurangkan jumlah baja N yang diperlukan untuk pertumbuhan.