Silicon improves rice nutrition and productivity under salinity

Abstract

Silicon (Si) is a beneficial nutrient for plant growth and productivity. Our investigation was conducted to study the influence of Si application for ameliorating the adverse effects of salinity on rice through sodium regulation in plant tissues. Three same textured soils (sandy clay loam) with different electrical conductivity (EC e : 2.85, 5.28 and 7.57 dS m-1) and pH (8.1, 8.6 and 8.9) were collected at 0-15 cm depth from the Bahauddin Zakariya University Agricultural Farm in Multan, Pakistan. The Si @ 50, 75 and 100 mg kg-1 as calcium silicate was applied to pots containing 10 kg sandy clay loam soil (sand 48%, silt 17%, clay 35%). A control without Si application was also maintained. The completely randomized design in 3 × 4 factorial experiment with three replications was established. Thirty days old, seedlings of Kernel Basmati rice were transplanted manually and standard cultural practices were followed. Results showed a significant (p<0.05) effect of soil salinity on rice growth and yield parameters. A reduction in grain, straw, leaf and root concentrations of Si, P and K/Na was observed under salinity; however, Si application at 100 mg kg-1 ameliorated the salinity stress and significantly increased the root/shoot dry weights, tiller numbers, grain numbers per spike, paddy yield, harvest index, and P and Si concentrations in root, straw, leaves and grains over control though similar to Si @ 75 mg kg-1 for shoot dry weight, number of tillers, harvest index, grain/root P concentration and leaf Si concentration. The Si application affected K/Na by increasing K uptake with an associated decrease in Na concentration in plant tissues. Thus, Si application at 100 or 75 mg kg-1 soil (200 or 150 kg ha-1) could be a useful strategy for rice production in salt-affected lands. Shoot dry weight, Number of tillers. Harvest index, Grain/root P conc., Leaf Si conc.

The Ability of Silicon Fertilisation to Alleviate Salinity Stress in Rice is Critically Dependent on Cultivar

“…Although some papers report a salinity-induced reduction in tissue Si (e.g. Ahmed et al 2019 ) many others show findings similar to ours, i.e. a substantial increase in Si (Mahdieh et al 2015 ; Abdel-Haliem et al 2017 ; Lekklar et al 2019 ).…”

“…A number of observations can be made on the outcomes of this experiment: first, there is little difference in the growth rate of cultivars under low vs high Si when salinity stress is absent, a phenomenon that has previously been reported (Yeo et al 1999 ; Lekklar et al 2019 ; Ahmed et al 2019 ; Yan et al 2021 ).…”

“…Ahmed et al ( 2019 ) found the beneficial effect of Si during salt stress in rice was similar for shoot dry weight and yield. We found that the impact of Si supplementation on mitigating salt stress was consistent across the two traits of biomass and yield for IR154, CSR28 and OM4900, but less so for IR64 (where yield rescue was only seen at EC = 4 dS m −1 while biomass rescue occurred at EC = 6 and 8 dS m −1 ), and not at all for IR74371, which showed biomass rescue but no effect of Si on yield.…”

“…Averaged across cultivars, growth rate reduction at low ambient Si was ~ 30%, whereas it was only ~ 15% at high ambient Si. Previous studies have focussed on overall biomass production rather than relative growth rates (RGR), but have nevertheless reported similar beneficial effects of Si (Flam-Shepherd et al 2018 ; Lekklar et al 2019 ; Ahmed et al 2019 ).…”

“…Salt induced depression of photosynthetic rates have also been shown to be partially reversed by Si (Farooq et al 2015 ). Overall, these effects of Si are associated with improved growth and yield during salt stress (Ahmed et al 2019 ).…”