Eco-Physiological Screening of Different Tomato Genotypes in Response to High Temperatures: A Combined Field-to-Laboratory Approach

Abstract

High temperatures represent a limitation for growth and development of many crop species. Several studies have demonstrated that the yield reduction of tomato under high temperatures and drought is mainly due to a photosynthetic decline. In this paper, a set of 15 tomato genotypes were screened for tolerance to elevated temperatures by cultivating plants under plastic walk-in tunnels. To assess the potential tolerance of tomato genotypes to high temperatures, measurements of chlorophyll fluorescence, pigments content and leaf functional traits have been carried out together with the evaluation of the final yields. Based on the greenhouse trials, a group of eight putative heat-sensitive and heat-tolerant tomato genotypes was selected for laboratory experiments aimed at investigating the effects of short-term high temperatures treatments in controlled conditions. The chlorophyll fluorescence induction kinetics were recorded on detached leaves treated for 60 min at 35 • C or at 45 • C. The last treatment significantly affected the photosystem II (PSII) photochemical efficiency (namely maximum PSII quantum efficiency, F v /F m, and quantum yield of PSII electron transport, Φ PSII ) and the non-photochemical quenching (NPQ) in the majority of genotypes. The short-term heat shock treatments also led to significant differences in the shape of the slow Kautsky kinetics and its significant time points (chlorophyll fluorescence levels minimum O, peak P, semi-steady state S, maximum M, terminal steady state T) compared to the control, demonstrating heat shock-induced changes in PSII functionality. Genotypes potentially tolerant to high temperatures have been identified. Our findings support the idea that chlorophyll fluorescence parameters (i.e., Φ PSII or NPQ) and some leaf functional traits may be used as a tool to detect high temperatures-tolerant tomato cultivars.Plants 2020, 9, 508 2 of 16 and quality [5,6]. Tomato (Solanum lycopersicum), being an excellent source of health-promoting compounds, is one of the most important crops cultivated worldwide and its heat sensitivity varies among different genotypes [4,7,8]. Generally, the optimal temperature range for photosynthesis is considered to be between 25 • C and 30 • C [6]. The rising of average temperatures due to the ongoing climate change will cause extensive productivity losses in Mediterranean areas, where tomato is traditionally cultivated [9][10][11]. In this framework, it becomes important to perform studies that are able to identify the most promising genotypes able to face heat stress.The relationship between gas exchange and crop yield has been largely studied in tomato, suggesting leaf transpiration as the most reliable indicator for yield prediction under drought [12]. However, beside gas exchange, other photosynthesis related parameters [13] should be taken into account to build a "eco-physiological identity card" for different genotypes.Chlorophyll fluorescence represents a good tool to rapidly and accurately detect plant health status, the occurrence of...

Evaluation of anatomical and physiological traits of Solanum pennellii Cor. associated with plant yield in tomato plants under water-limited conditions

“… 11 , and Egea et al . 28 , 30 recorded inferior g s values for S. pennellii under drought-stress conditions. As LA 716 showed high g s in the control treatment, statistically identical to g s values recorded for M82 ( p < 0.05), low g s values observed for LA 716 in the stress treatment are likely associated with stomatal closure rather than low stomatal density as suggested by Kebede et al .…”

“…At midday evaluation, g s mean value for S. lycopersicum was 4.6 times higher than that found for S. pennellii in the control treatment and 5.8 times higher in the stress treatment. www.nature.com/scientificreports/ Similarly, Torrecillas et al 9 , Rocha et al 11 , and Egea et al 28,30 recorded inferior g s values for S. pennellii under drought-stress conditions. As LA 716 showed high g s in the control treatment, statistically identical to g s values recorded for M82 (p < 0.05), low g s values observed for LA 716 in the stress treatment are likely associated with stomatal closure rather than low stomatal density as suggested by Kebede et al 14 and Egea et al 30 .…”

“…Here, we investigated the anatomical and physiological behavior of S. pennellii accession LA 716, four ILs (derived from LA 716 × M82 cross) previously selected as drought-sensitive (IL 2-5 and IL 7-1) and drought resistant (IL 3-5 and IL 10-1) www.nature.com/scientificreports/ and the cultivar M82 under two water regimes (50 and 100% ASW) in order to understand their importance to tomato breeding for drought resistance. Abiotic stresses are known for affecting since leaf functional traits and pigments of tomato plants until decreasing crop performance 28,29 . In this study, we also detected changes in leaf anatomy and gas exchange parameters when plants were subjected to limited water conditions, with contrasting behavior observed between the cultivated and the wild tomato species.…”

“…Abiotic stresses are known for affecting since leaf functional traits and pigments of tomato plants until decreasing crop performance 28 , 29 . In this study, we also detected changes in leaf anatomy and gas exchange parameters when plants were subjected to limited water conditions, with contrasting behavior observed between the cultivated and the wild tomato species.…”

Biochemical, Physiological, and Productive Response of Greenhouse Vegetables to Suboptimal Growth Environment Induced by Insect Nets

“…Plants exposed to high thermal stress activate their adaptive response by modifying their morpho-physiological, biochemical, and molecular properties [15,18]. Such stress alters photosynthetic and respiratory processes [19][20][21], impairs flowering and fructification [22,23], reduces enzymatic and chloroplastic activity [24,25], and promotes reactive oxygen species (ROSs) accumulation [26]. As illustrated by Hasanuzzaman et al [16], high temperatures activate the transcription of heat stress-responsive genes, resulting in the synthesis of signaling molecules; osmoprotectants; nonenzymatic antioxidant compounds such as ascorbate (AsA), glutathione (GHS), tocopherol, and carotene; and enzymatic antioxidant compounds such as catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD), peroxidase (POX), and glutathione reductase (GR).…”