Associations between first true leaf physiology and seedling vigor in cotton under different field conditions

Abstract

Rapid development of the first true leaf has been suggested as a key driver of seedling vigor in cotton, yet studies demonstrating an association between first true leaf physiological processes and early season cotton growth are limited. It was hypothesized that both first true leaf area (FTLA) and photosynthetic rates would be positively associated with cotton (Gossypium hirsutum and G. barbadense) seedling vigor, and that photosynthetic component processes would differ in their contribution to net photosynthesis (An) of the first true leaf. To test these hypotheses, three different cotton cultivars were planted in the 2017 and 2018 seasons on three selected dates each year to generate broad differences in seedling vigor. Growth analysis was conducted to assess seedling vigor at 3 and 5 wk after planting, and a combination of dark‐ and light‐adapted gas exchange and fluorescence measurements were performed on the first true leaf, concurrent with growth assessments. Seedling vigor was much more strongly associated with FTLA than An on a per unit leaf area basis, suggesting that FTLA was a stronger indicator of seedling vigor. Correlation analysis between An and a number of component processes derived from combined gas exchange and fluorescence measurements indicated that An was strongly correlated with electron transport rates and stomatal conductance. However, we suggest that most of the variability we observed in An of the first true leaf was primarily driven by nonstomatal factors, since no significant correlations between An and chloroplast CO2 concentration or substomatal CO2 concentration was apparent.

Considerations for Stand Establishment and Early Seedling Growth in Cotton

“…Small-plot studies conducted in Georgia also showed that largerseeded cultivars tended to have greater seedling vigor, especially when planted early in the season under sub-optimal temperature conditions (Virk et al, 2019(Virk et al, , 2020b. Other than cultivar, seed physical and chemical traits are also governed by environmental conditions (temperature, humidity) during seed development and storage.…”

Root system growth and anatomy of cotton seedlings under suboptimal temperature

“…Extensive research has been conducted on the factors affecting seedling vigour in cotton, and it is clear that cultivar and growth temperature are among the most important determinants of early‐season growth [Liu et al., 2015; Snider et al., 2014; Snider et al., 2016; Snider et al., 2018; Virk et al., 2019, 2020]. However, other than a few recently published works [Liu et al., 2019; St Aime et al., 2021; Singh et al., 2018], studies that have evaluated vigour as a function of root system development are limited.…”

“…vigour can be affected by cotton cultivar [Snider et al, 2014;Snider et al, 2016;Virk et al, 2019;Virk et al, 2020] and environmental constraints such as suboptimal temperatures that occur at or soon after planting (Snider et al, 2018).…”

“…Seedling vigour can be affected by cultivar within a given crop species and is an important consideration for seedling development and establishment. For example, previous research has documented a positive association between seed characteristics (including seed mass, calorie content and oil content) and early-season vigour under a range of field conditions (Liu et al, 2015;Pahlavani et al, 2008;Snider et al, 2014;Snider & Oosterhuis, 2015;Virk et al, 2019Virk et al, , 2020. While most of these studies focused on shoot growth, more recent work conducted by Liu et al (2019) Vigour can be assessed using a number of different growth parameters, but many studies (except for the few noted above) have focused on shoot growth parameters rather than roots.…”

Effect of Cotton Leafroll Dwarf Virus on Physiological Processes and Yield of Individual Cotton Plants

“…Table 1 shows weather conditions prevailing during seven day period proceeding the date of physiological measurements. Chlorophyll fluorescence assessments were also conducted at the same time using the methods and calculations discussed extensively elsewhere (Earl and Ennahli, 2004;Chastain et al, 2016;Meeks et al, 2019;Virk et al, 2020b). The primary fluorescence parameters of interest included actual quantum yield of photosystem II (Φ PSII ) and rate of electron flux through photosystem II (ETR).…”