Application of bacterial agents on sunflower

Abstract

The study was aimed to examine the effects of bacterial agents combined with two variants of mineral fertilization on the sunflower yield.

Materials and methods. The main field experiments were carried out in Department of Plant Production and Variety Investigations of the Plant Production Institute named after V.Ya. Yuriev of NAAS of Ukraine in 2016−2018.

The soil was deep granular slightly leached chernozem. It had the following agrochemical parameters: humus content (Tyurin’s method) 5.8%; pH 5.8; hydrolytic acidity 3.29 mg/eq per 100 g of soil. The nutrient reserves in the control (no fertilizer): nitrogen – 132 mg/kg; phosphorus – 104 mg/kg; potassium – 128 mg/kg. The nutrient amounts with mineral fertilizer (N₃₀P₃₀K₃₀): nitrogen – 130-140 mg/kg; phosphorus – 180−200 mg/kg; potassium – 170−190 mg/kg of soil.

Data were statistically processed by variance and correlation analyses.

Results and discussion. In2016-2018, sunflower plants grew and developed under very contrasting weather conditions compared to the multi-year averages. There was a water deficit during the critical periods (anthesis, seed setting and filling), especially at elevated air temperatures.

In the study, biofertilizer GroundFix + bacterial agent HelpRost turned out to be the most effective combination. When GroundFix was used at a dose of 5 L/ha without fertilizer, the yield increased by 0.33 t/ha compared to the control; when it was used with N₃₀P₃₀K₃₀ as basic fertilizer, the gain in the yield amounted to 0.36 t/ha. When the ‘GroundFix 5 L/ha + HelpRost’ combination was applied, the gain was 0.30 and 0.32 t/ha, respectively. The efficiency of HelpRost 3 L/ha in the “5−6 leaf pair” phase of the crop was -0.03 and -0.04 t/ha on the respective mineral fertilization. When the biofertilizer dose was increased to 8 L/ha, the yield was raised by 0.32 and 0.30 t/ha, respectively; when the increased dose was co-applied with HelpRost, the increment was 0.42 and 0.58 t/ha, respectively.

There was a strong positive effect of April temperatures on the yield, with correlation coefficient of 0.36− 0.72, and of June temperatures (r = 0.33−0.59), except for the ‘GroundFix 5 L/ha + HelpRost 3 L/ha’ combination on basic fertilization with N₃₀P₃₀K₃₀ (r = - 0.25 and r = - 0.07, respectively).

Conclusions. When GroundFix was used at a dose of 5 L/ha without fertilizer, the yield increment was 0.33 t/ha compared to the control; when GroundFix was used at the same dose with N₃₀P₃₀K_30, the increment amounted to 0.36 t/ha. By combining GroundFix 5 L/ha with HelpRost, we obtained the yield increments of 0.30 and 0.32 t/ha, respectively. Increasing the biofertilizer dose to 8 L/ha gave the yield gain of 0.32 and 0.30 t/ha, respectively. When the increased dose was co-applied with HelpRost, the gain was 0.42 and 0.58 t/ha, respectively.

There was a positive correlation (r = 0.37−1.00) between the yield and precipitation amount during the growing period. We noted a strong positive effect of April temperatures, with correlation coefficient of 0.36−0.72, and of June temperatures (r = 0.33−0.59).