Effects of silicate application on rice growth, yield and quality under nighttime warming in southern China

The main feature of climate warming is that nighttime warming is higher than the daytime warming. Nighttime warming reduced single rice production in southern China, while silicate application increased rice yield and stress resistance. It is still unclear regarding the effects of silicate application on growth, yield, and especially quality in rice under nighttime warming. We performed a field simulation experiment to investigate the effects of silicate application on tiller number, biomass, yield and quality of rice. Warming was set at two levels, ambient temperature (control, CK) and nighttime warming (NW). The open passive nighttime warming method was used, with rice canopy being covered with aluminum foil reflective film at night (19:00-6:00) to simulate nighttime warming. Silicate fertilizer (steel slag) was applied at two levels, i.e., Si₀(0 kg SiO₂·hm^-2) and Si₁(200 kg SiO₂·hm^-2). The results showed that, compared with the control (ambient temperature), average temperature at nighttime on rice canopy and at 5 cm soil layer increased by 0.51-0.58 ℃ and 0.28-0.41 ℃ during rice growing season, respectively. Nighttime warming decreased tiller number and chlorophyll content by 2.5%-15.9% and 0.2%-7.7%, respectively. In contrast, silicate application increased tiller number and chlorophyll content by 1.7%-16.2% and 1.6%-16.6%, respectively. Under nighttime warming, silicate application increased dry weight of shoot, total dry weight of the whole plant, and yield at grain filling-maturity stage by 64.1%, 55.3%, and 7.1%, respectively. Under nighttime warming, silicate application significantly increased milled rice rate, head rice rate, and total starch content by 2.3%, 2.5%, and 41.8%, respectively. Nighttime warming reduced rice yield by decreasing the number of effective panicles, seed setting rate, and 1000-grain weight, but increasing empty grains. Silicate application increased rice yield by increasing the number of effective panicles, filled grains per panicle, seed setting rate and 1000-grain weight, but reducing empty grains. In conclusion, silicate application could effectively alleviate the suppressive effects of nighttime warming on growth, yield, and quality of single rice in Southern China.