Effects of Silicon Application at Nano and Micro Scales on the Growth and Production of Potato Minitubers (Solanum tuberosum Var. Agria) under Three Soil Texture

Introduction: Many experiments have shown that Silicon (Si) can reduce the effect of both biotic and abiotic stresses in plants caused by plant diseases, pest damage, salinity, drought, heavy metal toxicity, nutrient imbalance, water logging, high radiation, high temperature, wounding, and freezing. It has been indicated that silicon has a beneficial role in plant nutrition such as enhancement in absorbing nitrogen, phosphor, potassium and zinc. Beneficial results of silicon application on plant growth and physiology made farmers and researches to use silicon as a fertilizer. Silicon fertilizers are applied as slag, compost, rice straw, calcium and sodium silicates in both foliar and soil applications. Potato is not considered as a Si-accumulating but studies have implied that Si supply may alleviate damaging effects that result from drought and also reduce stem lodging and increase tuber yield  increased leaf area, specific leaf area, and pigment concentration (chlorophyll a and carotenoids) as well as photosynthesis and transpiration rates of well watered potato plants. Materials and Methods: This experiment was conducted as factorial based on completely randomized design with three replications, in department of agronomy, Ferdowsi university of Mashhad, Iran, in 2015. In this research, the effects of four different silicon compounds (Nano-silica, sodium silicate, hydrophilic Bentonite (Nano-clay), and Bentonite), in two concentrations (1000 ppm and 2000 ppm) on the growth characteristics of potato Minitubers (Solanum tuberosum Var. Agria) plants and production under three different soil texture (clay loam, loam and sandy loam), were investigated. In order to determine the best treatment in each soil, variance analysis was done along with cluster analysis, stepwise multi regression analysis and path analysis, and the results of all analysis were compared. Resultsand Discussion: Due to the lack of development of plants in clay loam soil, the comparison between treatments was done only in loam soils and sandy loam soils. The results showed that despite the lack of leaf and stem development in silicon treated plants, the Minituber characteristics improved compared to the control, which resulted in an increase in the ratio of Minituber dry weight to shoot dry weight. based on plant performance, Cluster analysis for loam soil categorized silicate treatments in 3 groups: first (control, Bentonite (2000 ppm), Nano-silica (2000 ppm)), second (Nano-clay (1000 ppm), Bentonite (1000 ppm), Nano-silica (1000 ppm)) and third (Nano-clay (1000 ppm), Sodium Silicate (1000 ppm), Sodium Silicate (2000 ppm)). In loam sand soil this grouping was in four groups: first (control, Bentonite (1000 ppm), Nano-clay (1000 ppm)), second (Nano-clay (2000 ppm), Nano-silica (2000 ppm), Nano-silica (1000 ppm)), third (Bentonite (2000 ppm), Sodium Silicate (2000 ppm)) and forth (Sodium Silicate (1000 ppm)). Path analysis showed in loam soil three traits (leaf dry weight, total plant Minituber volume, total plant Minituber dry weight) have the most direct and indirect effect on Minituber fresh weight (as potato yield. In loam sand soil four traits (mean Minituber diameter, leaf area, total plant Minituber volume, total plant Minituber dry weight) were indicated to have the most direct and indirect effect on Minituber fresh weight (as potato yield). Conclusions: Investigating the effect of applying silicate treatments in different concentrations on Minituber wet weight (as Minituber yield) by cluster analysis and path analysis showed that in both soils, Bentonite (2000 ppm) had the most effect on traits responsible for Minituber wet weight changes.