Reaction of yield and yield components of wheat to paclobutrazole and growth-promoting bacteria at different levels of irrigation

Water is one of the most important needs of plants and drought stress is one of the most important stresses for plant growth. Given the global water shortage, provide solutions to save water consumption in agriculture, such as choosing the appropriate irrigation method, irrigation time management, providing methods to reduce and control the negative effects of water shortage on plants and the use of more resistant varieties to water shortage and The use of different techniques to reduce the effects of water scarcity is important and should be a priority for research. Paclobutrazole is a group of plant growth regulators of triazole that prevents the production of a wide range of gibberellic acid and has many applications in agriculture. Paclobutrazole reduces the negative effects of abiotic stress on plant growth by regulating the levels of hormones, enzymatic and non-enzymatic antioxidants and osmolytes. A group of beneficial soil bacteria that increase plant growth are called plant growth promoting bacteria and are among the most important types of biofertilizers. PGPRs by lat out of volatile organic compounds (VOC) increase biomass, plant tolerance to abiotic stresses and disease resistance.

This research was conducted as a factorial split plot in the form of a randomized complete block design with three replications in Qom and Hamedan regions (Hamedan is a cold and mountainous region with mild summer and Qom is a dry and desert region with hot and dry summers). Experimental factors include irrigation regime with three levels 1- (irrigation at 40% of available plant moisture discharge during the growing season (optimal irrigation), 2- optimal irrigation up to pollination stage and irrigation at 60% of available plant moisture discharge until the end of the growing season 3- Irrigation in 40% of available plant moisture discharge up to pollination stage and cessation of irrigation until the end of growing season), foliar application of paclobutrazole at three levels (zero, 50 and 100 ppm in two stages of stem and spike) and invoice The third included five levels of growth-promoting bacteria (non-consumption, Mycobacterium, Azotobacter, Azospirillium, and a combination of three bacteria). Irrigation regimen factors and paclobutrazol in the main plots and growth-promoting bacteria in the subplots. The traits evaluated in this experiment included parameters related to leaf chlorophyll fluorescence and Rubisco activity.

The results showed that the interaction effect of irrigation regime on paclobutrazol was significant for biological yield and grain yield, so that at the third irrigation level, the use of paclobutrazol at a concentration of 100 ppm increased grain yield and biological yield. Also, according to the analysis of variance table, the interaction effect of irrigation regime in bacteria for biological yield and grain yield was significant, so that in the third level of irrigation regime, two levels of combination of three bacteria and Azotobacter with 19.05 and 17.95 tons, respectively. Hectares had the highest biological yield.

In general, the results showed that in more difficult conditions of irrigation regime, the use of paclobutrazol can cause less decline and improve grain yield and biological yield. It can also be inferred that the use of growth-promoting bacteria increases grain yield and biological yield and improves morphological traits, and the combination treatment of Mycobacterium, Azotobacter and Azospirillium had the highest yield.