Field Evaluation of Rhizobacterial Inoculants in Combination With Humic Substances To Improve Seed and Oil Yields of Safflower (Carthamus Tinctorius L.) Under Irrigated and Rainfed Conditions

Abstract

The present study was evaluated the application of humic acid (HA), which possess multifaceted biological action, and plant growth promoting rhizobacteria (PGPR) inoculation to improve the morphologic performance, yield and seed quality of safflower under different water regimes in the Eastern Anatolia region of Turkey. In a 2-year field trial, the two humic acid level (200 and 400 kg ha(-1)) and the two rhizobacterial strains (Bacillus megatorium M3 and Bacillus subtilis OSU142) in together with control treatments were evaluated under irrigated and rainfed conditions using randomized complete block design with a split-split plot arrangement. Bacterial strains and humic acid levels highly increased plant growth, seed and oil yields, and seed nutrient contents under irrigated and rainfed conditions. However, the combined application of the OSU142 strain with 400 kg HA hat resulted in the greatest enhancement of safflower growth and yield under irrigated conditions, and seed and oil yields increased by 101.8 and 127.6% with treatment of 400 HA + OSU14 respectively. Moreover, the integrated use of humic acids and PGPR inoculation relatively showed additive effect in the growth and yields of safflower under rainfed conditions, and increased by 186.5 with treatment of 400 HA + OSU142 and 257.1% with treatment of 400 HA + M respectively.