Silicon partially preserves the photosynthetic performance of rice plants infected byMonographella albescens

Abstract

Leaf scald, caused by Monographella albescens, is one of the major diseases in rice worldwide. This study investigated the effect of silicon (Si) on the photosynthetic gas exchange parameters [net CO 2 assimilation rate (A), stomatal conductance to water vapour (g s ), transpiration rate (E)] and internal CO 2 concentration (C i ), chlorophyll (Chl) fluorescence a parameters [minimal fluorescence (F 0 ), maximum fluorescence (F m ), maximum quantum yield of photosystem II (F v /F m )], photochemical quenching coefficient (q p ), effective quantum yield of PSII [Y(II)], quantum yield of regulated energy dissipation [Y(NPQ)] and quantum yield dissipation non-regulated [Y(NO)] and the concentrations of pigments in rice plants grown in nutrient solutions containing either 0 (−Si) or 2 mM Si (+Si) and non-inoculated or inoculated with M. albescens. Leaf scald severity decreased with higher foliar Si concentration. For the inoculated +Si plants, A, g s and E were significantly higher in comparison with the inoculated −Si plants, in which C i was significantly increased. Similarly, the concentrations of Chl a , Chl b , total Chl a+b and carotenoids were higher for the +Si plants in comparison with the −Si plants. Changes in the images of Chl a fluorescence were first observed precisely on the −Si plants leaves in comparison with the +Si plants. A decrease of q P and Y(II) in inoculated −Si plants, in comparison with the inoculated +Si plants, was accompanied by an increase in Y(NPQ) and Y(NO). Notably, the extent of the leaf areas was much more evident for Y(II) and q P in comparison with F 0 , F m and F v /F m , suggesting that Y(II) and q P were good predictors in detecting the early effects of leaf scald on the leaf photosynthesis. For the +Si non-inoculated plants, changes in Y(II) were associated with alterations in both Y(NPQ) and Y(NO) compared with non-inoculated −Si plants. In conclusion, the photosynthetic performance (as demonstrated by the gas exchange and Chl a fluorescence parameters) and the pigment pools of rice plants infected with M. albescens were preserved by Si supply and, therefore, provided an increase in rice resistance against leaf scald.

Long-term effects of straw and straw-derived biochar on soil aggregation and fungal community in a rice–wheat rotation system

“…Therefore, CO 2 emission variation in CS and CB needs further exploration. Gibberella and Monographella , which cause soil-borne diseases in crops (Tatagiba, DaMatta & Rodrigues, 2016; Wang et al, 2018; Yan et al, 2018), were lower in CS and CB in the 0–20 cm layer, with their levels in CB exhibiting significant differences relative to those in CF ( p < 0.05). These reduced pathogenic fungal contents might lessen the probability of morbidity.…”

Chlorophyll Fluorescence Imaging Uncovers Photosynthetic Fingerprint of Citrus Huanglongbing

“…The value of NPQ_Lss in HLB infected and nutrient deficient leaves might be related to the different degrees of tissue damage, which can also be reflected from the severity of the HLB and nutrient deficient symptoms. Reported studies have revealed that the increase of the NPQ_Lss depends on the stimulated electron flow as a protection mechanism ( Tatagiba et al, 2016 ). What’s more, it indicates the excess excitation energy dissipated as heat in order to reduce the photooxidative damage, which is also coupled to a gradual loss of chloroplastic pigments in response to the HLB infection and nutrient deficiency, eventually resulting in blotchy yellowing symptoms in leaves.…”

Peer Review #1 of "Long-term effects of straw and straw-derived biochar on soil aggregation and fungal community in a rice–wheat rotation system (v0.1)"

“…Therefore, CO 2 emission variation in CS and CB needs further exploration. Gibberella and Monographella, which cause soil-borne diseases in crops (Tatagiba et al 2016;Wang et al 2018;Yan et al 2018), were lower in CS and CB in the 0-20 cm layer, with their levels in CB exhibiting significant differences relative to those in CF (p < 0.05). These reduced pathogenic fungal contents might lessen the probability of morbidity.…”