Sugarcane, a grass grown for its sweet stalks, naturally flowers as part of its reproductive phase. This flower signifies the plant’s shift from vegetative growth to reproduction. Understanding this biological event is important for sugarcane cultivation.
Appearance and Characteristics
The sugarcane flower, known as an “arrow” or “tassel,” is a large, plume-like structure extending from the top of the stalk. These inflorescences can reach up to 2 feet in length and vary in color, often appearing silvery-purple, cream-colored, or with a faint lavender hue.
Each tassel contains thousands of individual flowers arranged in a branched panicle at the stem tips. As panicles age, their color may turn whitish. The tassel’s appearance signals a key developmental stage for the plant.
The Flowering Process
Sugarcane flowering is influenced by several environmental factors. The main trigger for flowering is photoperiod, specifically a shortening of day length. Sugarcane is a short-day plant, requiring around 12.5 hours or less of daylight to begin flowering. This signals the plant to shift energy towards reproduction.
Temperature also plays a role in flowering. Optimum conditions include daytime temperatures around 28°C and nighttime temperatures near 23°C. Night temperatures below 18°C can prevent flowering. Adequate soil moisture promotes flowering. In the Northern Hemisphere, flowering typically initiates between July and August, emerging from September to November. In the Southern Hemisphere, initiation is from February to March, with emergence from April to July.
Impact on Sugar Yield
Sugarcane flowering has consequences for sugar production, as it diverts plant resources from sucrose storage. The plant mobilizes sucrose from stalks to develop flowers and seeds, reducing sucrose content. Juice purity can also decrease, affecting sugar extraction efficiency.
Flowering can cause pithiness, characterized by dry cavities within stalks with less juice. This impacts the cane’s final weight and extractable sugar. While some studies suggest a short-term sucrose yield increase if harvested soon after flowering, prolonged delays result in losses in cane tonnage and sugar quality.
Controlling Flowering in the Field
Managing sugarcane flowering is key to maximizing sugar yield in commercial fields. One strategy is selecting “shy-flowering” sugarcane varieties. Planting these varieties where later harvesting is planned mitigates yield losses. Manipulating planting times can also influence flowering, with autumn planting sometimes reducing its rate.
Water management is another control tool. Withholding irrigation during specific periods suppresses floral development. Applying chemical ripeners or growth regulators, like ethephon, also disrupts flowering, inhibiting flower formation and preventing energy diversion from stalks. Some growers use night light breaks to delay flowering. These practices aim to keep the plant focused on accumulating sugar in its stalks.