Response of Drip‐Irrigated Sugarcane to Drought Stress¹

Abstract

Though drip irrigation is used on more than half of the irrigated sugarcane (Saccharum spp. hybrid) in Hawaii, the effects of drought stress on the growth and yield of drip‐irrigated sugarcane has not been investigated extensively. This study reports the effects of a single period of drought stress on the growth and metabolism of cultivar H62‐4671 during vegetative growth in drip‐irrigated fields during the 1st year of a normal 2‐year crop in five fields at Kekaha Sugar Company, Kauai, Hawaii. The plants ranged from 5.4 to 9.8 months of age at the beginning of the experiment. Water depletion from the soil profile, leaf water potential (ψΙ), leaf solute potential (ψΠ), leaf pressure potential (ψρ), stalk elongation, plant sugar, K, and amino acid concentrations were monitored at 1200 to 1400 hour during a 5‐ or 6‐week period of drought stress. In three of four fields, soil water extraction was limited by low soil water content after cumulative profile water depletion of approximately 120 mm. Stalk elongation was strongly correlated to ψΙ and cumulative soil water depletion. Stalk elongation of plants in drought‐stressed plots was less than 80%' that of plants in well‐watered plots after only 50 mm of cumulative soil water depletion. During drought the concentrations of potassium and reducing sugars in the leaf blade increased, but the concentrations of sucrose and free amino acids changed little. None of these metabolites changed in the stem apex. The results indicate that a serious reduction in stalk elongation occurs prior to a reduction in the rate of soil water depletion, a change in the false‐color infrared signature of the canopy, or large changes in ψΙ, ψΠ, leaf and meristem sugar, K, and amino acid concentrations. The results emphasize the importance of maintaining normal imgation intervals with drip‐irrigated sugarcane cv. H62‐4671.

Climatic effects on sugarcane ripening under the influence of cultivars and crop age

“…Several authors have described the effects of water defi cits on processes such as leaf expansion and stalk elongation (Hill, 1966;Kingston and Ham, 1975;Jones, 1980;Koehler et al, 1982;Inman-Bamber and De Jager, 1988;Roberts et al, 1990;Nable et al, 1999), leaf senescence (Inman-Bamber and De Jager, 1988;Inman-Bamber, 1994), sucrose content, dry matter (Inman-Bamber and De Jager, 1988) and photosynthesis (Roberts et al, 1990). However, recent studies have shown that tillering and intense growth phases are the most critical to water defi cit, since the most of sugarcane biomass is produced during these periods (Ramesh and Mahadevaswamy, 2000;Inman-Bamber and Smith, 2005).…”

Sugarcane Yields and Yield‐Limiting Processes

“…In the Hawaiian cultivar H62-4671, relative SER (RSER, the ratio of SER of stressed to unstressed plants) reduced rapidly as L decreased below −0.6 MPa and was only 0.1 when L decreased below −1.3 MPa (Koehler et al 1982). As L can decrease to −1.0 MPa or less even in well-irrigated plants (Roberts et al 1990), it can be expected that water stress-induced reduction in SER will be difficult to avoid even with frequent irrigation.…”

Stress Physiology: Abiotic Stresses

“…The role of proline in osmoregulation and the contribution of osmoregulation to drought adaptation remain uncertain in sugarcane. Koehler et al (1982) showed a large increase in the concentration of potassium, reducing sugars, and organic acids occurred in the leaf blade during drought but the amount of free amino acids and sucrose remained unchanged. It appears that potassium is the dominant substance involved in osmoregulation in both stressed and nonstressed plants, contributing nearly 65 and 52% of , respectively.…”