Water deficit stress mitigation by foliar application of potassium silicate for sugar beet grown in a saline calcareous soil

Drought stress is a serious abiotic factor that limit yield and quality of many crops grown in newly reclaimed lands of Egypt. A field experiment in split-plot design was conducted to assess the usefulness of potassium silicate [K2SiO3 (K-silicate)] on alleviating drought stress on sugar beet grown in a calcareous soil. The main plots were assigned for three irrigation intervals as 8, 14 and 20 days, whereas the subplots were assigned for four K-silicate foliar spray concentrations (0, 500, 1000 and 2000 mg L-1 silicate). The results indicated that increasing the irrigation interval from 8 to 14 and 20 days caused a significant reduction in sugar beet yield. However, irrigation with interval 14 days and spraying K-silicate at concentrations of 1000 mg L-1 silicate gave root fresh yield of 51.65 Mg ha-1, compared with 38.81 mg L-1 obtained without spraying K-silicate. Likewise, spraying K-silicate in concentration of 1000 mg L-1 silicate increased N, P and K removal in shoot by 66.0, 15.5 and 134.2 kg ha-1 and in root by 152.0, 34.4 and 244.2 kg ha-1, respectively. These values were 64.6, 14.2 and 122.6 kg ha-1 in shoot and 128.4, 29.0 and 223.1 kg ha-1 in root without spraying K-silicate, respectively. Spraying K-silicate showed also the potential to increase fertilizer use efficiency, and hence can save fertilizers. For instance, increasing irrigation interval to 14 days without spraying K-silicate gave partial factor productivity (PFP) of N, P and K fertilizers to the levels of 647, 1252 and 1552 kg root kg-1 fertilizer, respectively. However, spraying K-silicate at concentration of 1000 mg L-1 silicate increased these values to 861, 1666 and 2066 kg root kg-1 fertilizer, respectively. In conclusion, this study suggests that spraying K-silicate has the potential to alleviate the negative effects of drought stress on sugar beet yield grown in calcareous soils.