Multifunctional biologics which combine microbial anti-fungal strains with chitosan improve soft wheat (triticum aestivum l.) yield and grain quality

Abstract

The developing of effective and high-tech preparations for microbiological plant protection is a crucial problem of agricultural biotechnology. In this paper, we revealed differences in the crop structure, grain introscopic characteristics and resistance of soft wheat plants to root rot when using novel multifunctional bioactive preparations. Our objective was to investigate effects of developed bioactive compositions based on microbial antagonists of plant pathogenic and chitosan complexes on spring soft wheat (Triticum aestivum L.) variety Leningradskaya 6. Plant protection against root rot, productivity and grain quality assessed by the methods of microfocus X-ray radiography and gas discharge visualization were estimated in two-year field tests (Leningrad Province, 2016-2017). The weather conditions during growing season of 2016 were more favorable for wheat plants compared to 2017 due to a slight temperature fluctuation and a significant amount of precipitation. The number of spikelets per spike, flag and pre-flag leaf area, the weight of spike and vegetative parts were the indicators for wheat productivity, germination energy, seedling length, dynamics of plant growth phase and height, the number, length and weight of roots. According to significant positive influence of the studied compositions on yield structure, the biopreparations rank as follows: in 2016 — Vita plan, Zh (ООО AgroBioTekhnologiya, Russia) > Vitaplan, Zh + Chitosan II (test preparation con taining 50 and 100 kDa chitosans with the addition of 0.1 % vanillin, FSBSI VIZR) > Gamair, SP (ООО AgroBioTekhnologiya, Russia) > Chitosan I (test preparation containing 50 and 100 kDa chitosans with the addition of 0.05 % salicylic acid, FSBSI VIZR) > Chitosan II; in 2017 — Vita plan, Zh > Vitaplan, SP > Vitaplan, Zh + Chitosan II > Gamair, SP > Chitosan II. In 2016, a combined use of Vitaplan, Zh and Chitosan II changed significantly not only the plant vegetative part weight, but also the spike weight, while separate use of Chitosan II significantly increased the vegetative biomass only. In 2017, the same combination of the biologicals made the flag leaf 86.84 % larger and the root weight 83.33 % higher compared to the control. In 2016, Chitosan I led to reliable 19.0 % increase (t = 3,0; р < 0.05) in potential grain yield compared to the control, however, there were no significant differences for Vitaplan, Zh, Chitosan II and their combination Vitaplan, Zh + Chitosan II. On the contrary, in 2017 Vitaplan, Zh + Chitosan II caused the maxi mum reliable (t = 7.2; p < 0.05) increase in yield (by 82.6 %). Vitaplan, Zh and Vitaplan, Zh + Chi 1024 tosan II possess maximum efficiency against Helminthosporium root rot. Due to Vitaplan, Zh + Chi tosan II, in 2016 root rot disease frequency was 80 % lower compared to the control, and in 2017 no symptoms were observed which may be due to less favorable weather conditions for root rot disease in 2017 compared to 2016. According to our findings, the potential grain yield in wheat correlates significantly and positively with grain X-radiographic projection area, integrated grain brightness and total intensity of the gas-discharge fluorescence. Chitosan I, Chitosan II and Vitaplan, F + Chitosan II have the greatest impact on grain structure and quality parameters assessed by X-ray and gas discharge visualization. Perhaps the effectiveness of the studied drugs depended on weather condi tions, but was generally positive in terms of the main assessed indicators. Thus, our data convincingly indicate the effectiveness of multifunctional biologics which combine microbial antagonists of fungal plant pathogens with chitosan, an activator of plant diseases resistance, to protect wheat against root rot, to increase grain yield with better quality.