PHYSIOLOGICAL AND BIOCHEMICAL RESPONSES INDUCED BY RHIZOBACTERIA IN OIL PALM SEEDLINGS SUBMITTED TO WATER DEFICIT (Atena Editora)

Abstract

The oil palm (Elaeis guineensis Jacq.) is an important oilseed crop for the whole world. However, water deficiency can directly affect the development of seedlings in nurseries. The use of plant growth-promoting rhizobacteria is a potential strategy to induce drought tolerance and reduce plant mortality in the field. The objective of the study was to evaluate the ability to maintain photosynthetic performance and relieve oxidative stress in oil palm seedlings inoculated with rhizobacteria and subjected to water deficit. The experiment was carried out in a greenhouse in a completely randomized design. The treatments consisted of 8 seedlings inoculated with Bacillus amyloliquefaciens (UFRAB01) and 8 non-inoculated seedlings (control) of oil palm evaluated at two times: before and after the imposition of water deficit. The inoculation increased height and diameter of the stem in relation to the control in irrigated seedlings and in water deficit. Leaf water potential was affected only by water deficit with an increase in modulus of 180%. Inoculation managed to maintain higher mean values of net photosynthesis and carboxylation efficiency compared to non-inoculated seedlings. In the condition of water deficit, the levels of MDA and activity of the CAT enzyme, however the activity of the APX enzyme increased in the inoculated seedlings. Therefore, the water deficit drastically reduced the photosynthetic performance of all oil palm seedlings, and the inoculation of UFRAB01 mitigated the damage to the photosynthetic apparatus to maintain the highest averages of net photosynthesis in relation to the non-inoculated seedlings. Under field conditions, UFRAB01 inoculation can induce greater tolerance to moderate drought and decrease seedling mortality.