Examining reaction of sunflower genotypes on planting time on chernozem soil

Abstract

We studied the effect of planting time on plant pathological factors, leaf area index and yield production by applying various fungicid treatments on two different sunflower genotypes in 2013.
 By delaying planting time, both the extent of Diaporthe, Alternaria and Phoma infections decreased. The differences between the volume of infections were significant in the case of the early and late sowing time results. The application of fungicide treatments induced a notable decrease in the extent of infections for all three pathogens examined. The LAI-values varied between 0.3 and 5.6 m2/m2 in 2013 depending on the hybrid, sowing time and treatment. Stocks planted at distinct times reached maximum leaf coverage at different times. The planting time and the fungicide treatment had a significant effect on the formation of the leaf area. In the case of average and late planting times, fungicide treatments elongated the preservation of the green leaf area.
 With respect to the yield amount, average planting time (27 April, 2013) turned out to be optimal in 2013 (control – NK Ferti: 4.621 kg ha-1, PR64H42: 4.196 kg ha-1; double-treated: NK Ferti: 5.282 kg ha-1, PR64H42: 5.090 kg ha-1). Fungicide treatments resulted in significant yield growth in all cases during our research.
 We applied Person correlation analysis to evaluate the hybrids’ sensibility to infections and our results varied in the case of Diaporthe and Phoma (r=-0.343*, -0.379**). Infections of the three pathogens were significantly reduced by delaying the planting time and applying fungicides. Late sown stocks preserved the green leaf area for a longer period. Besides, the application of the fungicide treatment and the hybrid itself also led to the preservation of the green leaf area. However, pathogens examined notably decreased the leaf area by the end of the growing year. The fungicide treatment had a remarkable effect on yield growth (r=0.603**). Furthermore, the presence of higher LAI-values in the period prior to August also induced higher yields.