Effects of microbial fertilizers on the chlorophyll a fluorescence responses of tomato plants

Plant growth-promoting bacteria in rhizosphere improve plants’ growth in different ways. In this study, the effects of five growth promoting bacteria, in the form of three biofertilizers were investigated on the chlorophyll a fluorescence changes of tomato seedlings.

The experiments were conducted as factorial based on a completely     randomized design. The bacteria were Azotobacter chroococcum, Azospirillum lipoferum,  Bacillus lentus, Pseudomonas putida and Acidithiobacillus thiooxidans; and biofertilizers were nitroxin, biosporphosphate and biosulfur. Chlorophyll a fluorescence changes were recorded using a Handy PEA device and analyzed by the JIP-test method.

The results showed that the use of Azotobacter chroococcum and Azospirillum ipoferum caused L band formation about 15 microseconds after light exposure, which revealed an improvement in the grouping and connectivity of antenna chlorophylls with photosynthetic reaction centers. Besides, the formation of the K band about 0.3 milliseconds after light exposure showed that the performance of the water-splitting complex was increased under the influence of Azotobacter chroococcum and Azospirillum lipoferum. The increase in electron transfer efficiency and the rate of reduction of the end electron acceptors in photosystem I were confirmed by the formation of J, H, and G bands in the presence of plant growth-promoting bacteria. 

The results of this study proved that the best photosynthetic performance in tomato plants including electron transfer between carriers of the photosynthetic electron transport chain occurred in the nitroxin bio-fertilizer containing Azotobacter chroococcum and Azospirillum lipoferum.