Interactive effect of silicon and mycorrhizal inoculation on growth, yield and water productivity of rice under water-deficit stress

Drought is a major abiotic stress limiting growth and productivity of field and horticultural crops. Exogenous application of silicon (Si) and arbuscular mycorrhizal fungi (AMF) inoculation has the potential to alleviate the adverse effect of drought stress on plant. A factorial experiment consisting of four monosilicic acid (MSA) doses (0, 75, 150 and 300 kg ha(-1)), two levels of AMF inoculation (inoculation of AMF [+AMF] and without inoculation of AMF [-AMF]) and three soil moisture regimes (100%, 75% and 50% field capacity [FC]) was conducted to evaluate the effect of Si and AMF inoculation on growth, yield and water productivity of rice under water-deficit stress. The soil moisture regimes of 75% and 50% FC indicate a 25% and 50% depletion of the maximum amount of water held in the soil, respectively, whereas 100% FC refers to the maximum amount of water held in the soil after gravitational water drainage stops. An overall reduction in growth and yield of rice was observed with decreasing soil moisture regime; however, application of 300 kg MSA ha(-1) increased shoot dry matter by 28% compared with 0 kg MSA ha(-1) under limited soil moisture availability of 75% and 50% FC. Similarly, grain yield was increased by 37% and 39% at 300 kg MSA ha(-1) compared with the control in the -AMF and + AMF plants, respectively, under moderate soil moisture level of 75% FC. The corresponding increase at 50% FC was 52% and 55%, respectively. The present results demonstrated a synergistic effect of exogenous application of MSA at 300 kg ha(-1) (60 kg ha(-1) soluble Si) and AMF inoculation on rice under water-deficit stress.