Browsing by Subject "Silicon"

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Entwicklung innovativer Pflanzenschutzprodukte und -verfahren als umweltfreundliche Alternativen zur Bekämpfung von Mehltaupilzen : Bericht im Rahmen des Forschungsprojektes: „Silizium als Aktivator bei Kulturpflanzen“
(2019) Raupp, Manfred G.; Weinmann, Markus; Arbeitsgemeinschaft industrieller Forschungsvereinigungen „Otto von Guericke“ e. V. (AiF) Projekt GmbH, Berlin; Madora GmbH, Lörrach; Römheld, Volker; Neumann, Günter; Blaich, Rolf; Merkt, Nikolaus
Powdery mildews are among the most important diseases in many crop plants. In all sectors of crop production (agriculture, viticulture, horticulture and orchards) powdery mildew fungi can cause severe damage under field as well as greenhouse conditions. Although organic synthetic fungicides have been used to combat powdery mildews in conventional and integrated agriculture for decades, organic farming lacks effective alternatives to the ecologically questionable sulfur fungicides. Yet, also for integrated or conventional crop production, alternatives or supplements for a reduction and more effective use of synthetic fungicides would be desirable to optimize the production of high quality food with the help of environmentally friendly means. Objective of the present work was the development of innovative crop protection products and application strategies to combat powdery mildew fungi with respect to the knowledge on resistance-enhancing effects of an improved silicon (Si), manganese (Mn) and zinc (Zn) supply to the plants. Furthermore, various plant extracts have recently received renewed attention. Among other active natural agents, garlic (Allium sativum L.) is known for its fungitoxic effect and at the same time high Mn and Zn contents. With the present work, an overview of possible approaches to control powdery mildew in grapevine by use of Si, Mn, Zn and plant extracts from garlic has been elaborated in greenhouse experiments. In this regard, the physiological significance of Si, Mn and Zn for the expression and strengthening of plant own resistance mechanisms was distinguished from the effectiveness of spray applications for forming passive silicate crusts as mechanical infection barriers. The physiological Si status of the plants could be clearly improved only by soil rather than foliar application of silicates. Regarding the soil application of silicates, however, no practical applications are known, how silicon fertilizers can be distributed under field conditions in the soil and brought into the rhizosphere to continuously ensure high rates of Si uptake. There is also still considerable uncertainty whether the soil application of silicates in non-Si accumulators, such as grapevines, can result in sufficient Si uptake for an effective expression of resistance mechanisms. The most impressive effects in the control of powdery mildew were achieved with the spray application of potassium silicate in combination with wetting agents to form silicate crusts on the leaf surface. The positive influence of Mn and Zn on the effectiveness of spray applications of potassium silicate and the adequate compatibility of Mn and Zn chelates with potassium silicate suggest that the interactions between Si, Mn and Zn should be considered for further product development. The application of garlic extract did not result in sufficient efficiency, although protective and curative properties could be observed. Allicin, supposed to be the active ingredient of garlic extract, has a broad spectrum of antimicrobial activity and is one of the few agents for which no development of resistance has been found in microorganisms so far. Therefore, the interest in this agent for the development of biological plant protection products is expected to increase.
Silicon seed priming combined with foliar spray of sulfur regulates photosynthetic and antioxidant systems to confer drought tolerance in maize (Zea mays L.)
(2021) Farman, Muhammad; Nawaz, Fahim; Majeed, Sadia; Javeed, Hafiz Muhammad Rashad; Ahsan, Muhammad; Ahmad, Khawaja Shafique; Aurangzaib, Muhammad; Bukhari, Muhammad Adnan; Shehzad, Muhammad Asif; Hussain, Muhammad Baqir
The present study evaluated the effect of silicon (Si) seed priming and sulfur (S) foliar spray on drought tolerance of two contrasting maize hybrids viz. drought tolerant Hi-Corn 11 and susceptible P-1574. The maize seeds were primed with (3 mM Na2SiO3) or without Si (hydropriming) and later sown in pots filled with sandy loam soil. Drought stress (25–30% water holding capacity or WHC) was initiated at cob development stage (V5) for two weeks, whereas the well-watered plants were grown at 65–70% WHC. On appearance of drought symptoms, foliar spray of S was done using 0.5% and 1.0% (NH4)2SO4, whereas water spray was used as a control. The drought-stressed plants were grown for further two weeks at 25–30% WHC before the final harvest. The results showed a marked effect of Si seed priming and foliar S spray on biomass, physiological and enzymatic processes as well as macronutrient concentrations of maize. In comparison to control, the highest increase in leaf relative water content (25%), chlorophyll a content (56%), carotenoids (26%), photosynthetic rate (64%), stomatal conductance (56%) and intercellular CO2 concentration (48%) was observed by Si seed priming + S foliar spray (Si + S) under water deficit conditions. Also, Si + S application stimulated the activity of catalase (45%), guaiacol peroxidase (38%) and superoxide dismutase (55%), and improved NPK concentrations (40–63%) under water limitations. Our results suggest that Si seed priming + foliar spray of S is more effective than the individual application of these nutrients to enhance drought tolerance in maize.