Silicon improves rice grain yield and photosynthesis specifically when supplied during the reproductive growth stage

Abstract

Silicon (Si) has been recognized as a beneficial element to improve rice (Oryza sativa L.) grain yield. Despite some evidence suggesting that this positive effect is observed when Si is supplied along the reproductive growth stage (from panicle initiation to heading), it remains unclear whether its supplementation during distinct growth phases can differentially impact physiological aspects of rice and its yield and the underlying mechanisms. Here, we investigated the effects of additions/removals of Si at different growth stages and their impacts on rice yield components, photosynthetic performance, and expression of genes (Lsi1, Lsi2 and Lsi6) involved in Si distribution within rice shoots. Positive effects of Si on rice production and photosynthesis were manifested when it was specifically supplied during the reproductive growth stage, as demonstrated by: (1) a high crop yield associated with higher grain number and higher 1000-grain weight, whereas the leaf area and whole-plant biomass remained unchanged; (2) an increased sink strength which, in turn, exerted a feed-forward effect on photosynthesis that was coupled with increases in both stomatal conductance and biochemical capacity to fix CO; (3) higher Si amounts in the developing panicles (and grain husks) in good agreement with a remarkable up-regulation of Lsi6 (and to a lesser extent Lsi1). We suggest that proper levels of Si in these reproductive structures seem to play an as yet unidentified role culminating with higher grain number and size.

Effects of Silicon and Zinc Nanoparticles on Growth, Yield, and Biochemical Characteristics of Rice

“…According to Yuva Raj and Subramanian, (2014), application of Zn as NP improved the rice growth because it released nutrients slowly and gradually during critical growth stages. Application of Si (2 mM) at the reproductive growth stage of rice caused a 45% increase in GY compared with no Si application (Lavinsky et al, 2016). Application of Si significantly increased rice GY by 89, 51, 33, and 32% at treatments of 1, 10, 50, and 100 μg L −1 Zn, respectively, compared with control or without application of Si (Mehrabanjoubani et al, 2015).…”

Induction of Barley Silicon Transporter HvLsi1 and HvLsi2, increased silicon concentration in the shoot and regulated Starch and ABA Homeostasis under Osmotic stress and Concomitant Potassium Deficiency

“…Down-regulation of HvLsi6 also was observed in barley by Si supply (Yamaji et al, 2012 ). The reported variation in the expression of Si transporters in different studies mentioned above might be due to species dependent response (Lavinsky et al, 2016 ) or different ways of Si or stress treatments. For instance, as described by Ma and Yamaji ( 2015 ), rice contains two Casparian strips and both OsLsi1 and OsLsi2 cooperate for Si uptake and transport between symplastic and apoplastic pathways, while barley and maize comprises of only one Casparian strip and Si is first taken up from external solution by HvLsi1 or ZmLsi1 and then released to the stele by HvLsi2 or ZmLsi2 .…”

Is silicon capable to affect the photosynthetic performance of green maize plants?

“…It is possible that the Si was not only deposited in the shoot cell wall of vegetative development (Ali et al, 2013), although, the maize plants have Si accumulation (Ma and Yamaji, 2015). Crop plants, for example, rice, show panicles increase to plants treated with Si and the supply of Si was beneficial to the commercial grain production (Lavinsky et al, 2016). These authors affirm that the Si plays a physiological function on photosynthesis, which is justified by the increase in stomatal conductance and ability to atmospheric CO 2 assimilation.…”