Correlation Among Phenotypic Parameters Related to the Growth and Photosynthesis of Strawberry (Fragaria × ananassa Duch.) Grown Under Various Light Intensity Conditions

Abstract

The objective of this study was to investigate characteristics of phenotypic parameters such as physiology, yield, and fruit quality responses of strawberry (Fragaria × ananassa Duch.) to various light intensity conditions (VLICs), and to determine the correlations among these phenotypic parameters. Strawberry plants were cultivated in a smart greenhouse separated into four areas, three of which were completely shaded by curtains from 20:00 until 10:00 (3 hS), 12:00 (5 hS), and 14:00 (7 hS), respectively. The fourth area was a non-shaded control treatment (0 hS). The ambient light intensities during the experimental period for the 0, 3, 5, and 7 hS treatments were 1,285, 1,139, 770, and 364 mol⋅m–2, respectively. Strawberry plants grown under low light intensity conditions experienced decreases in photosynthetic rate, stomatal conductance, and sugar accumulation compared to the 0 hS. Petiole generation and fruit yield were also sharply decreased in proportion to the degree of decrease in light intensity. In contrast, photosynthetic pigment content was shown to increase under low light conditions. Organic acid contents (excluding acetic acid) and leaflet size did not change significantly under low light conditions compared to the 0 hS. Changes to light intensity are considered to induce changes to the phenotypic characteristics of strawberry plants to favor growth using the energy and carbon skeletons obtained through respiration and photosynthesis. In the 7 hS treatment, where light intensity was drastically reduced, NPQ, qP, and RFd values as chlorophyll a fluorescence parameters were significantly lowered, which could indicate their measurement as an important technique to check the stress response of plants grown in low light conditions.

Shading Inhibits Sugar Accumulation in Leaf and Fruit of Jujube (Ziziphus jujuba Mill.)

“…Under shading conditions, plants might maintain the original photosynthetic rate by changing photosynthetic pigment contents and chl a/b ratio or adapt to low light by reducing the photosynthetic rate [3,28]. In this study, compared with no shading, the chlorophyll and carotenoid contents in shaded leaves increased significantly at the later stage, while the chl a/b ratio decreased, which was consistent with the reports of strawberry and rice [2,29]. The results indicated that shaded jujube leaves obtained higher light energy by increasing photosynthetic pigment contents and meanwhile improved photosynthetic phosphorylation activity by reducing the chl a/b ratio [30,31].…”

“…The decrease in sucrose content after shading was more obvious than for fructose and glucose, which was consistent with reports for nectarine and wax apple [36,37]. Results of strawberry [2], maize [34,38], and soybean [39] showed that, under low light conditions, the decrease in the photosynthetic rate of leaves led to a weakening of the carbon assimilation capacity, thus seriously affecting sugar synthesis [40]. Therefore, the suppression of sucrose synthesis caused by the decreased photosynthetic rate was the main reason underlying the inhibition of the sugar accumulation in jujube leaves under shade conditions; the reduced carbohydrate accumulation then repressed vegetative growth [37].…”

“…The decrease in sucrose cont after shading was more obvious than for fructose and glucose, which was consistent w reports for nectarine and wax apple [36,37]. Results of strawberry [2], maize [34,38], a The sucrose, fructose, and glucose contents in fruits were positively correlated with each other. Sucrose content was positively correlated with ZjSS2, ZjSPS1, ZjnINV1, ZjcINV3, and ZjHK3 expression but negatively correlated with ZjSPS4 expression.…”

“…The photosynthetic pigments content was determined by acetone extraction [2]. Fresh leaves (0.5 g) were ground with 5 mL acetone and extracted in the dark for 24 h at 4 • C. The absorbance at different wavelengths (663 nm, 645 nm, and 480 nm) was measured using a spectrophotometer (SUMMIT, China) to calculate chlorophyll a (chl a), chlorophyll b (chl b), total chlorophyll (total chl), and carotenoid content.…”

“…Light is one of the most important environmental factors affecting plant growth, nutrient absorption, yield, and quality of fruit [1]. Low light intensity is a crucial element restricting fruit production in some regions, being influenced by global climate change, geographical location, and cultivation facility [2,3]. Insufficient light could decrease fruit weight and yield [4], reduce fruit quality [5][6][7], and even promote abscission [8,9].…”