Study the effect of plant growth biostimulants application on quantitative and qualitative characteristics of wheat in a calcareous soil (Case study in Khuzestan)

Despite the abundance of some nutrients in calcareous soils, the available form of these nutrients is less than the amount required for plant growth, and the deficiency of nutrients is one of limiting factor in the production of plants especially wheat in these soils. The application of plant growth biostimulants may improve the availability of nutrients in calcareous soils and consequently increase yield and grain quality of wheat. Therefore, this study was conducted to evaluate the effect of plant growth biostimulants on quantitative and qualitative characteristics of wheat in a calcareous soil.

This research was conducted in randomized complete design with seven treatments and three replications at Behbahan Agricultural Research Station in one year (2017-2018). Treatments included: control (application of chemical fertilizers according to soil test), free amino acid (L), fulvic acid, seaweed extract, humic acid, grain inoculation with Azotobacter and application of all studied biostimulants (except fulvic acid). Foliar application of amino ccid, fulvic acid and seaweed extract was done at a concentration of 0.5 % at two stages, tillering and heading. Humic acid was used as fertigation at 5 kg.ha-1 in the early stages of growth (prior to tillering). During experiment: plant height, number of spikes per m2, number of grain per spike, 1000- grain weight, grain yield, biomass, grain protein, phosphorus, potassium, copper, zinc, manganes and iron of grain were measured. Varince analysis were done by MSTATC statistical software and meanes were compared using Duncan,s Multiple Range Test at the 5% prpbability level.

The effect of biostimulants on grain yield was significant at the 1% prpbability level. A significant increase in grain yield observed in plants treated with biostimulants compared with control. The highest plant height (99 cm), number of spikes per m2 (633), number of grain per spike (43.33), 1000-grain weight (46.12 g) and grain yield (8617.71 kg.ha-1) were recorded in the combined treatment. The differences of grain yield among this treatment and other treatments were significant. Application of biostimulants significantly increased the grain protein percentage, the concentration of potassium, copper, zinc, manganes and iron of grain at the 1% prpbability level. These formulations had no significant effect on grain phosphorus. Application of combined biostimulants significantly increased the grain protein percentage, potassium, copper, zinc, manganes and iron of grain compared with control. Among growth biostimulants, the highest increase in the grain protein percentage and grain iron was achieved by amino acid while the highest increase in potassium, copper, zinc and manganese of grain was obtained by humic acid compared with control.

The combined use of plant growth biostimulants produced the best grain yield and quality in comparision to alone of these substances.Therefore, inoculation of wheat seeds with Azotobacter, use of humic acid as fertigation at in the early stages of growth and foliar application of amino ccid and seaweed extract at two stages of tillering and heading, are recommended. According to the results, among growth biostimulants, application of amino acid or humic acid is preferred.