Investigating the effect of silicon and potassium foliar spraying and additional soil application of potassium on quantitative and qualitative yield of sugar beet (Betavulgaris L.) under moisture stress conditions

Deficit water resources is one of limitations of sugar beet cultivation and the use of compounds that can be improved growth and sugar beet production is the most important research priorities. Potassium plays a main role against deficit water. Potassium has great effect on keeping down Osmotic potential of root cells. Its existence is critical for duration preservation and create the pressure on poke and adjustment water balance on plants. Existence of potassium has special importance in keeping water plant's tissue.. Silicon has the potential to be used in the production of floriculture crops to increase flower and stem size, accelerate flowering and improve resistance to stresses including drought. Silicon (Si) is a non-essential nutrient for most plants. However, in field crops it is known to affect plant growth and quality, photosynthesis, transpiration and enhance plant resistance to stresses such as drought. Si enhances physical and chemical defense power of plants. However, beneficial effects of Si are most obvious in high Si-accumulating plant species Si plays a significant role in modulating physiological and metabolic responses in plant. This study investigated into role of foliar spraying Silica and Potassium on the sugar beet (Beta vulgaris L.) under deficit Irrigation. In order to study the effects of foliar spraying silicon and Potassium on quantitve and qualitative yield of sugar beet under conditions of irrigation deficit, two experiments were conducted a split plot arrangement based on randomized complete block design with three replications in two regions of Mashhad and Fariman and analyzed as complex in 2016. Main plots were allocated to irrigation treatments including: 100, 75 and 50 percent of water requirement and sub plots were allocated to four fertilizer levels including: control, Potassium, Silicon, Potassium with Silicon. Promoter system (OS-1 model) for stomatal conductance and chlorophyllmetr system for chlorophyll index and Betalizer and Sugarmetr system were used to measuring qualitative traits. The results showed that interactions of fertilizer treatments on yield, root Potassium, stomatal conductance and chlorophyll index at 1% level and Sugar content, Extraction coefficient of sugar and Molasses sugar were significant at 5% level. The simple effects of fertilizer treatments were on Sodium and Amino nitrogen significant at 1% and 5%, respectively. In the case of water adequacy, Application of silica and potassium fertilizers had an increasing effect and increased the yield by 12.9% and in a mild stress condition (75% water requirement), increased by 21%, chlorophyll index and 37% stomatal conductance and 14.5% yield compared to the control. The application of silica and potassium fertilizers under severe drought stress (50% water requirement) did not affect quantitative yield. But reduced the molass sugar by 47%. The use of these two elements reduced the amount of sodium and nitrogen contaminants by 26% and 21.5%, respectively. The results showed that the correlation between the amount of potassium and silicon leaves and yield and Sugar content was positive. For best results, the minimum weights of potassium and silicon leaves should be 4.5 and 3.5 mg / kg, respectively. In general, the results showed that simultaneous use of silica and potassium fertilizers had an increasing effect and could improve the quality and quantity of beet in different irrigation regimes