Leaf rolling dynamics for atmospheric moisture harvesting in wheat plant as an adaptation to arid environments

Abstract

Plant species surviving in the arid regions have developed novel leaf features to harvest atmospheric water. Before the collected water evaporates, it is absorbed and transported for storage within the tissues and move toward the root zone through the unique chemistry of leaf structures. Deep insights into such features reveal that similarities can be found in the wheat plant. Therefore, this study aimed to evaluate the leaf rolling dynamics among wheat genotypes and their relationships with moisture harvesting and its movement on the leaf surface. For this purpose, genotypes were characterized for leaf rolling at three distinct growth stages (tillering, booting, and spike emergence). The contact angle of leaf surface dynamics (adaxial and abaxial), water budget, and morphophysiological traits of genotypes were measured. The results indicate that leaf rolling varies from inward to twisting type among genotypes and positively affected the water use efficiency and soil moisture difference at all growth stages under normal and drought conditions. Results of wetting property (hydrophilic < 90°) of the leaf surface were positively associated with the atmospheric water collection (4-7 ml). The lower values of contact angle hysteresis (12-19°) also support this mechanism. Thus, genotypes with leaf rolling dynamics (inward rolled and twisted) and surface wettability is an efficient fog harvesting system in wheat for interception and utilization of fog water in drought-prone areas. These results can be exploited to develop self-irrigated and drought-tolerant crops.

Keywords: Abaxial; Adaxial; Atmospheric water; Contact angle; Drought; Dynamics; Hydrophilic; Root zone; Wheat.

Fig. 1

Wheat plant harvesting mechanism; a plant growing under fog events, b a leaf with fine droplets, c side view of a leaf showing attachment of droplets, d stem flow toward the base, and e moisture at the base of the plant

Fig. 2

Water budget of selected 15 wheat genotypes in natural fog events and under field conditions. Results are presented as mean ± SEM

Fig. 3

The static contact angle of leaf dynamics (adaxial and abaxial) of 15 wheat genotypes. Results are presented as mean ± SEM

Fig. 4

Correlation plot of leaf rolling (LR), leaf erectness (LE), water budget (WB), physiological parameters viz photosynthesis (P), transpiration (T) and water use efficiency (WUE), and contact angle (CA (adaxial) and (abaxial)) of 15 wheat genotypes. The blue shade shows a positive correlation, and the pink shade shows a negative correlation. The size of the circle shows how traits are associated with each other

Fig. 5

Biplot analysis of leaf traits viz leaf rolling (LR), leaf erectness (LE), physiological parameter viz photosynthesis (P), transpiration (T), and water use efficiency (WUE) of selected 15 wheat genotypes at tillering (a), booting (b), and spike emergence (c) stage grown under normal (N) and drought (D) field conditions. Circle explains the theoretical maximum extent of the arrows, added by the default confidence interval of 68%. Arrows show the correlation among the traits for their respective environment

Fig. 6

Biplot analysis of yield traits viz flag leaf area (FLA), peduncle length (PL), ear length (EL), plant height (PH), days to heading (DH), days to maturity (DM), ear weight/spike (EW), seed weight/spike (SW), spikelets/spike (S), no. of seed/ear (SE), and grain yield/plot (Y) of selected 15 wheat genotypes grown under normal (N) and drought (D) field conditions. Circle explains the theoretical maximum extent of the arrows added by the default confidence interval of 68%. Arrows show the correlation among the traits for their respective environment

Fig. 7

Correlation plot of leaf traits viz leaf rolling (LR), leaf erectness (LE), moisture difference (MD), physiological parameters viz photosynthesis (P), transpiration (T) and water use efficiency (WUE), and yield parameters viz flag leaf area (FLA), peduncle length (PL), ear length (EL), plant height (PH), days to heading (DH), days to maturity (DM), ear weight/spike (EW), seed weight/spike (SW), spikelets/spike (S), no. of seed/spike (SE), and yield/plot (Y) of 15 wheat genotypes grown under normal (a) and drought (b) field conditions. The blue shade shows a positive correlation, and the pink shade shows a negative correlation. The size of the circle shows how traits are associated with each other. *Indicates significant (P < 0.05) and without sign (*) indicates nonsignificant (P ≥ 0.05)

Fig. 8

Heatmap of leaf traits viz leaf rolling (LR), leaf erectness (LE), moisture difference (MD), physiological parameters viz photosynthesis (P), transpiration (T) and water use efficiency (WUE), and yield parameters viz flag leaf area (FLA), peduncle length (PL), ear length (EL), plant height (PH), days to heading (DH), days to maturity (DM), ear weight/spike (EW), seed weight/spike (SW), spikelets/spike (SS), no. of seed/spike (SE), and yield/plot (Y) of 15 wheat genotypes grown under normal (N) and drought (D) field conditions