Morphological Responses of Sugarcane to Long‐Term Flooding

Abstract

Sugarcane (Saccharum spp.) in south Florida is often subjected to flooding due to intense summer rainfall or tropical storms. While there has been considerable research on the response of sugarcane cultivars to high water tables, there is a lack of information on cultivar morphological adaptation to long-term flooding. An experiment was established in Belle Glade, FL to examine: (i) effects of a July-September flood on the morphological characters of cv. CP 80-1743 and CP 72-2086 and (ii) significant flood 3 cultivar interactions that could be used to screen sugarcane germplasm. Sugarcane leaf, stem, primary root, adventitious root, and aerenchyma development were measured in the plant cane (2003) and second ratoon crops (2005). Morphological changes in response to flooding were similar in both years, with flooding leading to a 38% reduction in leaf weight, 4 to 15 times greater adventitious root development, 108% greater aerenchyma pipe extension, and 115% greater aerenchyma pipe diameter. Both cultivars responded to flooding by producing aboveground adventitious roots at the expense of belowground primary root biomass. A significant cultivar 3 flood interaction on aerenchyma extension and diameter was noted. Under nonflooded conditions, CP 72-2086 produced constitutive aerenchyma more than halfway up the stalk, whereas CP 80-1743 produced aerenchyma only 10% up the stalk. Aerenchyma development up the stalk may be a useful screening tool to identify flood-tolerance in sugarcane cultivars.

Changes in photosynthesis, growth, and sugar content of commercial sugarcane cultivars and Erianthus under flood conditions

“…Plants exposed to 60 d of flooding showed a slightly decreased growth rate in all the sugarcane cultivars and Erianthus. This result was related to the findings of previous studies that flooding inhibited leaf expansion and decreased LA, LAI, and leaf weight (Gilbert et al, 2007;Gomathi et al, 2014;Jaiphong et al, 2016), whereas flooding for < 3 mo less damaged LAI (Gilbert et al, 2008). Flooding also decreased stem weight on 90 DAT, which is consistent with a previous finding that water logging over 15-60 d at the grand growth phase decreased yield by approximately 5-30% because of the lack of nutrition and water uptake (Gomathi et al, 2014), while 3 mo of flooding decreased the yield by 18-37% in plant cane and 61-63% in a second ratoon (Gilbert et al, 2008).…”

“…Sugarcane growth has been shown to be restricted via decrease in metabolic activity of roots because of hypoxia occurring during flood conditions (Gomathi et al, 2014). Plants adapt to flooding by developing adventitious roots with well-developed aerenchyma to assist the maintenance of root activity and the supply of required oxygen, and also contribute to higher dry matter accumulation (Drew, 1997;Gilbert et al, 2007;Gomathi et al, 2014;Jaiphong et al, 2016).…”

Effects of duration and combination of drought and flood conditions on leaf photosynthesis, growth and sugar content in sugarcane

“…It has previously been reported that flooding for 3 mo led to a 4-15 times increase in root development, a 108% greater aerenchyma pipe extension, and a 115% greater aerenchyma pipe diameter (Gilbert et al, 2007), while flooding for 120 d to a level 30 cm above the top of the soil led to sugarcane clone I 6-04 having the highest root dry weight at 28.3 g/plant (Begum et al, 2013). During floods, plants produce roots and exhibit ethylene-dependent death and lysis, which lead to the formation of continuous gas-filled channels (aerenchyma) that help the plants to maintain their root activity and supply the necessary oxygen (Drew, 1997).…”

“…Thus, the numerous roots that grow during floods are better adapted to these conditions than the original roots, containing well-developed aerenchyma (Laan et al, 1991). Since root elongation was closely related to the oxygen concentration in the root zone, the internal aeration of the plants may have been achieved by increasing the root porosity and developing aerenchyma, which may have helped the plants to continue to take up water and nutrients, and may have offset any losses associated with flooding (Begum et al, 2013;Gilbert et al, 2007;Gomathi et al, 2014). However, following drainage, it was found that some of the original roots were damaged, and the adventitious roots dried out and became non-functional.…”

“…It has been found that the application of periodic flooding every mo leads to a 50% reduction in the photosynthesis rate (Viator et al, 2012) and reduced plant growth as a result of a decrease in the metabolic activity of the roots due to hypoxia (Gomathi et al, 2014). However, the plants concurrently develop adventitious roots from the nodes above the soil (Begum et al, 2013) -and when the flood lasts for 3 mo, the sugarcane plants produce adventitious roots with well-developed aerenchyma, which may help plants to continue to take up water and nutrients (Gilbert et al, 2007(Gilbert et al, , 2008.…”