Evaluation of Plant Growth Bacteria (PGPR) on Number of node Leaves and Capsules in Sesame Plant under Field Condition

Soil bacteria plays an important role in bio-geochemical cycles that cause soil ecosystem dynamics to return nutrients to life cycles. In recent days, these organisms can serve as complementary or, in some cases, alternative fertilizers, to maintain the sustainability of the agricultural ecosystem. On the other hand, the production of high-yielding cultivars has increased the consumption of agricultural inputs, especially fertilizers, which has caused a crisis of environmental pollution. Bacteria are soil microorganisms that are involved in the nutrient cycle of the soil, can improve plant growth, and are known as growth promoting bacteria (PGPRs). Approximately two to five percent of root-borne bacteria are in the group of growth-promoting bacteria. These bacteria improve plant growth in a variety of ways, including nitrogen fixation, synthesis and production of iron-complex ingsiderophore, production of plant hormones, production of antibiotics and fungicide compounds. Soil has a wide range of organic phosphate sources that must be converted to its inorganic form by enzymes such as phosphatase, phytase and phosphonostat, and bacteria in the Bacillus and Pseudomonas groups can be produced by the production of acid phosphatases that dissolve phosphates to help absorb them by plant. Another group of bacteria such as Azotobacter and Azospirillum have the ability to stabilize nitrogen. Sesame (Sesamum indicum L.) is one of the oldest oilseed plants and has been named as the queen of oilseed plants and compatible with arid and semi-arid regions. Lowing sesame yield per unit area necessity to exerted agronomic management practice. The number of capsules is the main components of yield that has highly correlated with it. The aim of this study was to investigate the effect of biofertilizers on number of capsules per node of leaves sesame plant under field conditions.

An experiment was conducted as factorial arrangement based on a randomized complete block design with three replications at Mashhad Agricultural and Natural Resources Research and Education Center during two growing seasons (2017-2018 and 2018-2019). The first factors were: seeds single capsule and multi-capsule seed types and second factors were four Biofertilizers: 1) Nitroxin® (containing Azotobacter and Azospirillum bacteria), 2) Biophosphorus® (containing phosphatase-solubilizing bacteria of genus Bacillus and Pseudomonas), 3) Equal mixture of Nitroxin and biophosphorus and 4) control. At planting time, seeds were inoculated with biological fertilizers by standard method, away from direct light and foliar spraying was done in 50% reproductive stage with the bio fertilizer treatments. The morphological traits (plant height, number and length of lateral branches, number and dry weight of leaves, number of nodes, number of capsules, number of single and multiple capsules nodes were measure per plant and biomass and seed yield were measured per unit area. Data was analyzed using MSTAT-C and means was comparison with LSR at the 5% probability level.

Application of biofertilizers increased plant height by 11 to 19.9 cm compared to no fertilizer treatment (89.1 cm). In the second year, the number of nodes was about 43% higher than the first year. Triple interaction treatments showed that in the second year and in single capsule seeds the application of nitroxin and biophosphorus fertilizer had the highest number of nodes (85.7) and the lowest amount of it was observed in single seed capsule plants in the first year. The highest number of single capsule nodes was obtain in the application of biofertilizer (nitroxin+ biophosphorus) in single capsule seeds. In the second year, the number of single capsule nodes in both seed types was more than 29 per plant. In the second year, the highest number of multi-capsule nodes was recorded from multi-capsule seeds with use of nitroxin and biophosphorus combination fertilizers. Interaction between treatments of seed type and biofertilizer results showed that plant was growth from multi-capsule seed had a positive reaction to biofertilizer so that in multiple seed type the number of capsule per plant was more than 57 in application of biofertilizer. Both in the first and second year, in the multiple seed capsule type, the use of biofertilizers produced more grain yield per square meter than other treatments.

The results of this study showed that consuming of biofertilizers together that containing Azotobacter, Azospirillum, Bacillus and Pseudomonas had a positive significant effect on the plant height, number of capsules per node leaf, biomass and number of capsule that lead to increase of seed yield in sesame plant. Therefore, it is recommended that seeds inoculate with these bacteria in sowing time and applying one foliar spraying in mid-flowering time lead to enhance sesame yield.