Quantum efficiency of photosystem II and production of orange under salt stress and nitrogen fertilization

Abstract

A B S T R A C TThis study aimed to evaluate the salt tolerance of 'Mimo do Céu' orange grafted onto three rootstocks using physiological parameters such as maximum quantum efficiency of photosystem II (PSII) and the production of fruits. It also evaluated the effectiveness of increased nitrogen (N) fertilization in reducing the effects of salt stress. Two concomitant experiments were carried out under controlled conditions, using drainage lysimeters. The Experiment I evaluated the effects of the application of five levels of saline water on three combinations of scion-rootstocks grafted with 'Mimo de Ceu' orange, in a randomized block design with three replicates in a 5 x 3 factorial scheme. The Experiment II evaluated the application of two N levels (100 and 200% of recommendation) in three scion-rootstock combinations irrigated with water of electrical conductivity of 3.0 dS m -1 , in a 3 x 2 factorial scheme, with three replicates. The maximum quantum efficiency of PSII was inhibited in citrus plants under salt stress. 'Mimo do Ceu' orange grafted onto 'Common' Rangpur lime has higher yield potential. The increase in N dose did not reduce the deleterious effects of water salinity on fruit production.Eficiência quântica do fotossistema II e produção de laranjeira sob estresse salino e adubação nitrogenada R E S U M O Objetivou-se, com este trabalho, avaliar a tolerância ao estresse salino da laranjeira 'Mimo do Céu' enxertada em três porta-enxertos utilizando como parâmetros fisiológicos, a eficiência quântica do fotossistema II e a produção de frutos. Também se avaliou a eficiência máxima do incremento da adubação nitrogenada na redução dos efeitos do estresse salino; para tanto foram realizados dois experimentos concomitantes em condições controladas e com auxílio de lisímetros de drenagem. No Experimento I foram estudados em blocos casualizados com três repetições, em esquema fatorial 5 x 3, cinco níveis de salinidade da água e três combinações de copa/porta-enxerto e no Experimento II estudou-se a aplicação de duas doses de N (100 e 200% da recomendação) em plantas das três combinações de copa/porta-enxerto irrigadas com águas de condutividade elétrica de 3,0 dS m -1 , em esquema fatorial 3 x 2 com três repetições. A eficiência máxima quântica do PSII foi inibida nas plantas cítricas com estresse salino; já o aumento do teor salino da água de irrigação reduz a produção de frutos e a laranjeira 'Mimo do Céu' enxertada no Limoeiro Cravo 'Comum' possui maior potencial produtivo. O aumento na fertilização nitrogenada não reduziu os efeitos da salinidade sobre a produção total de frutos.

Photochemical efficiency and growth of sugar apple under irrigation with saline water and foliar nitrogen

“…photochemical efficiency in energy transfer from P680 to the electron transport chain(Lin et al, 2013). A similar fluorescence increase trend due to N fertilisation was observed bySousa et al (2016) in orange (Citrus spp. ), whereas Figueiredo et al (2019) evaluated the chlorophyll efficiency in sugar apple seedlings 60 days after sowing and observed no significant influence of N fertilisation.…”

Influence of Citrate Nanoparticles on Photochemical Activity, Resistance to Pathogens and Productivity of Wheat

“…The results investigation of Peña-Olmos et al (2013) showed that toxicity caused by an excess of iron induced an increased level of stress in the broccoli plants, causing decreased of the value of photosystem II's (PSII) maximum quantum yield (Fv/Fm). The maximum quantum efficiency of photosystem II was inhibited in citrus plants under saline stress (Sousa J.R.M., et al, 2016). In investigations Jia M. et al ( 2019) were shown, that the Fv/Fm of wheat leaves was tended to increase with increasing N application.…”

Gas exchange, photosynthetic pigments, and photochemical efficiency of sesame under salt stress and phosphate fertilization

“…The Fv/Fm ratio showed a quadratic behavior, with a maximum point (0.802) reached at 88% of the recommended P rate, which represents an increase of 3.11% relative to that seen in plants subjected to 40% of the recommended rate (Figure 5D). There are reports that plants under no stress show quantum efficiency of photosystem II (Fv/Fm) in the range of 0.75 to 0.85 and that Fv/Fm values below or above this range reflect photoinhibitory damage to the reaction centers of photosystem II (Cruz, Cruz, Ferreira, Castro, & Almeida, 2014;Freire, Dias, Cavalcante, Fernandes, & Lima, 2014;Sousa et al, 2016;Guidi, Lo Piccolo, & Landi, 2019). Although the lowest value for Fv/Fm (0.776) was obtained in plants grown under 40% P 2 O 5 (Figure 5D), it must be considered that there was no photochemical damage, as it is within the range established by the abovementioned authors.…”