Soil moisture tension effect on sugar cane growth and yield

An experimental plot was established in Campeche, México, to assess the effect of moisture tension on sugarcane growth and yield. Irrigation and water efficiencies were calculated as well as the cane and sucrose virtual water contents. Three levels of soil moisture tensions (−15 kPa in T1, −45 kPa in T2, −75 kPa in T3) were used to begin irrigation in treatments compared with a control without irrigation (T4), in an experimental randomized block design. Height and stem diameter were significantly higher (p ≤ 0.05) in T1, treatment where also significantly higher cane and sucrose yields were observed (134.7 and 19.9 t ha−1, respectively). No significant differences in industrially relevant variables for the quality of sugar cane juice were found, although in T3 the highest Brix degrees and sucrose content in juice were obtained. Also in this treatment the highest irrigation water use efficiency (IWUE) was found, with an average increase in cane weight of 405 kg mm−1. Overall, the IWUE and the total water use efficiencies were directly and inversely proportional to the soil moisture tension, respectively. Irrigation water applied varied from 14.0 to 19.56% of the total water depth received by the crop for treatments T3 and T2, respectively, and contributed to a gain in cane and sucrose yields of 179-252%, and from 181 to 242%, for T3 and T1 treatments, respectively. For total cane and sucrose virtual water values, a direct relationship with the soil moisture tension was found. The highest value in cane blue virtual water was found in T2 (0.0274 m3 kg−1) and the lower in T3 (0.0247 m3 kg−1). In contrast, higher values of cane green virtual water were found at higher soil moisture tensions (Control treatment, 0.271 m3 kg−1). Since the final sucrose yield was strongly linked to the cane yield, a very similar behavior as for cane blue and green virtual water values was observed for sucrose blue and green water contents.