Characteristics of Leaf Stomata and Their Relationship with Photosynthesis in Saccharum officinarum Under Drought and Silicon Application

Abstract

Silicon (Si) plays an important role in the sustainable agriculture industry. The increasing demand for crop production with a significant reduction of synthetic chemical fertilizers and pesticide use is a big challenge nowadays. The use of Si has been proven to be an environmentally sound way of enhancing crop productivity by facilitating plant growth and development through either a direct or indirect mechanism, especially in tropical and subtropical regions. In particular, it has been investigated for its role in water stress management. The aim of the current experiment was to examine the protective role of Si in the photosynthetic capacity of different leaf segments and the ultrastructure of sugarcane ( Saccharum officinarm ) plants under water stress. Sugarcane cv. GT 42 plants were supplied with 0, 100, 300, and 500 mg L –1 Si and exposed for 60 days under each stress condition such as 100–95, 55–50, and 35–30% of field capacity. For the photosynthetic responses, each leaf was observed and separated into three equal parts (base, middle, and tip). We used intact leaves and were able to assess leaf photosynthetic responses. Under moderate and severe stress conditions, applied Si increased the photosynthesis (base, ∼16–143%; middle, 20–66%; and tip leaf part, 41–71%), transpiration rate (base, 15–97%; middle, 26–68%; and tip leaf part, 6–61%), and stomatal conductance (base, 26–137%; middle, 12–70%; and tip leaf part, 7–75%) in sugarcane plants. Ultrastructural examination of sugarcane leaves using scanning electron microscopy showed the remarkable effects on stomata ultrastructure. Silicon increased plant growth development, photosynthetic efficiency, and biomass/yield, and promoted better adaptation of stomata to drought. This study suggests that the application of Si may be used to increase the stress tolerance of sugarcane plants.

Predication of Photosynthetic Leaf Gas Exchange of Sugarcane (Saccharum spp) Leaves in Response to Leaf Positions to Foliar Spray of Potassium Salt of Active Phosphorus under Limited Water Irrigation

“… 6 , 12 , 54 Limited water irrigation levels could significantly downregulate sugarcane photosynthesis and productivity. 18 , 55 …”

“… 17 , 20 , 21 The closure of stomatal openings is an initial effect to limited irrigation and an efficient way to decrease the loss of water when stress is not too severe; however, it limits carbon dioxide diffusion in the plant leaves for photosynthetic capacity. 18 , 22 , 23 The requirement of water under field conditions has been a serious issue since most agricultural areas suffer from seasonal water stress conditions. 4 , 10 , 24 …”

Silicon Induced Drought Tolerance in Crop Plants: Physiological Adaptation Strategies

“…Improving the inorganic phosphorus content will promote the synthesis of ATP needed in the CO 2 assimilation cycle [48]. In photosynthetic reactions, more work is needed to disclose the significant of Si because very little is known on Si′s role in diurnal variations in plant photosynthetic efficiency [34].…”

“…Chen et al [28] indicated that Si-mediated enhancement of leaf gas exchange ability in Oryza sativa plants during water-stressed was correlated with stomatal and nonstomatal variables. Gong and Chen [33] and Verma et al [34] demonstrated the diurnal variations of photosynthetic traits in wheat and sugarcane plants subjected to water stressed conditions with loss in stomatal conductance. However, Si enhanced the photosynthetic efficiency during day time.…”

“…These observations suggested that stomatal and non-stomatal variables were associated in the maintenance of photosynthetic CO 2 assimilation by Si. Ming et al [34] and Verma et al [2] demonstrated that Oryza and Saccharum spp. both enhanced transpiration incase Si application safe and subjecting to drought stress.…”