Uniconazole and nitrogen fertilization trigger photosynthesis and chlorophyll fluorescence, and delay leaf senescence in maize at a high population density

Abstract

Ci-intercellular carbon dioxide concentration; E-transpiration rate; ETR-photosynthetic electron transport rate; F0-minimal fluorescence yield of the dark-adapted state; Fm-maximum fluorescence yield of the dark-adapted state; Fv-variable fluorescence; Fv/Fm-maximal quantum yield of PSII photochemistry; gs-stomatal conductance; MDA-malondialdehyde; PN-net photosynthetic rate; POD-peroxidase; qN-nonphotochemical quenching coefficient; qp-photochemical quenching coefficient; SOD-superoxide dismutase; ФPSII-effective quantum yield of PSII photochemistry.

Both uniconazole and 5-aminolevulinic acid increase maize (Zea mays L.) yield by changing its ear morphology and increasing photosynthetic efficiency and antioxidants in saline-alkali land

“…In this study, S3307 and ALA treatments also markedly slowed down the decline rate of PN, gs, and E and increased the Ci in maize leaves after silking stage, which plays a key role in maintaining stomatal opening, improving leaf carbon assimilation capacity and photosynthetic rate, helping to delay maize leaves senescence, therefore increasing the yield. The results are positive and in agreement with those studies of Ahmad et al (2021a), which found the same phenomena. As illustrated in this study, compared with that of the two regulators, the regulation effect of ALA treatment was better than that of S3307, but there was no significant difference between the two regulators.…”

“…influence photosynthetic efficiency via driving gas exchange and the ability of crops to absorb and utilize CO2 and thus reduce crop yield (Liu et al 2013, Wang et al 2017, Zhao et al 2019. Previous studies showed that PN in plant leaves decreased along with gs and E, but Ci increased gradually under stress (Ahmad et al 2021a, Wu et al 2021). After the silking stage, gs and E gradually decreased.…”

“…Experiment design: According to the screening tests of the applicable concentration of PGRs in our preliminary experiment, the optimum spraying concentration was 25 mg(S3307) L -1 (Ahmad et al 2021a) and 40 mg(ALA) L -1 (Beyzaei et al 2015), with tap water as the control (CK). Foliar spraying at the stage of nine expanded leaves (225 L ha -1 ) was carried out at about 17:00 h in the sunny and windless afternoon.…”

“…Leaf senescence is accompanied by decreasing chlorophyll (Chl) content, soluble sugar, and soluble protein, and increasing the MDA accumulation. Leaf senescence affects PSⅡ of maize and is mainly manifested in the obstruction of stomatal opening and closure, leading to a decreased net photosynthetic rate, transpiration rate, and stomatal conductance, but increases intercellular CO2 concentration (Ahmad et al 2021a). Due to the decrease in photosynthesis, maize cannot accumulate and transform organic matter normally, thereby decreasing the maize yield (Ren et al 2016.…”

Using Waste Sulfur from Biogas Production in Combination with Nitrogen Fertilization of Maize (Zea mays L.) by Foliar Application

“…It is clear that nitrogen significantly affects photosynthesis and chlorophyll fluorescence of the plant. This was demonstrated by the response of maize to nitrogen fertilization in a study by Ahmad et al [ 53 ], in which the effect of nitrogen application increased the electron transport rate, photochemical quenching coefficient, variable fluorescence, maximal quantum yield, and effective quantum yield of PSII photochemistry. A significant increase in Φ PSII values in three maize varieties due to a high nitrogen dose was demonstrated by Jin et al [ 52 ].…”