Browsing by Author "Van der Linde, Jacques Henry"

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    Does zinc influence germination, vegetative growth or yield of wheat (triticum aestivum)?
    (Stellenbosch : Stellenbosch University, 2018-03) Van der Linde, Jacques Henry; Pieterse, P. J.; Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy.
    ENGLISH ABSTRACT: Nutrients are essential to all life on earth. Nutrients are divided into macro and micro-nutrients. Macro nutrients such as proteins and carbohydrates for example are needed by organisms in large quantities to remain healthy while micro nutrients such as vitamins and minerals for example are needed in very small quantities. A lack in sufficient uptake of either macro or micro nutrients by organisms can lead to serious health problems, due to the occurrence of nutrient deficiencies. Emphasis has been laid on the importance of zinc (Zn; a micro nutrient) as more than 50% of soils on which staple foods (e.g., wheat) are produced globally are considered as being Zn deficient. Various secondary advantages such as decreased emergence rate, increased disease resistance, better stand density and yield have been linked to an improvement in wheat vigour due to an increase in the Zn concentration [Zn], either in wheat seeds, in the soil or due to foliar applications of Zn. The main aim of the study was to determine what the causal effects of increased [Zn] are on these various parameters. The influence of seed [Zn], priming and foliar applications of Zn fertilisers were either studied in uncontrolled or controlled environmental conditions. Various stress aspects, including water stress, increased planting depth and weed competition were also incorporated into some of the controlled environmental experiments. It is noteworthy that no Zn deficient (< 22 mg kg-1) seeds were used during these experiments as none could be found. An increase in wheat seed [Zn] did have a significant positive influence (p < 0.05) on the germination percentage of wheat seeds during the germination experiment. Soil moisture and planting depth had a significant influence on seedling growth (p < 0.05). Seemingly, insufficient amounts of soil moisture led to decreased seedling growth while an increase in planting depth led to a decrease in seedling emergence. Wheat seed emergence was also significantly (p < 0.05) improved due to an increase in wheat seed [Zn]. Wheat seed germination and seedling growth was not influenced by the presence of ryegrass, but the presence of only one wheat plant had a significant influence on the dry mass (DM) production of ryegrass (p < 0.05). Wheat stem length and DM actually increased in one of the experiments as the number of wheat plants decreased and the number of ryegrass plants increased. This finding was corroborated by other similar studies and also by two of the controlled environmental condition experiments in this study. Seed [Zn] and different fertilizer treatments had an indifferent influence on plant growth and nutrient composition at all three localities where field trails were conducted. Results were inconclusive as to whether seed [Zn] did have a positive influence on growth and vigour of wheat, which may have been attributed to the absence of truly Zn deficient wheat seeds in this instance.