Produtividade, eficiência de uso da água e qualidade tecnológica de cana‑de‑açúcar submetida a diferentes regimes hídricos

Abstract

Resumo -O objetivo deste trabalho foi avaliar a produtividade de colmos e de açúcar, a eficiência de uso da água e os atributos tecnológicos de cinco variedades de cana-de-açúcar de maturação precoce e seis de maturação média à tardia, submetidas ao regime de sequeiro (1.141,4 mm) e à irrigação plena (1.396,6 mm). Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições. A produtividade de colmos das variedades RB92579, RB72454 e SP81-3250 apresentou ganhos superiores a 180%, com uso da irrigação. A irrigação promoveu aumentos na produtividade de açúcar superiores a 200%, nas variedades RB92579 e RB943365. A irrigação plena proporcionou maior eficiência de uso da água, com produção média de 70,2 kg ha -1 mm -1 de colmos a mais em comparação ao regime de sequeiro. Com exceção das variedades RB72454, RB763710 e RB943365, não houve diferença nos atributos tecnológicos entre a irrigação plena e o regime de sequeiro. As variedades RB92579 e SP81-3250 de maturação média à tardia se destacam quanto à produtividade de colmos e de açúcar e à eficiência de uso da água, e são recomendadas para estudos de resposta à irrigação pela cana-de-açúcar.Termos para indexação: Saccharum, cana-planta, irrigação plena, sequeiro. Productivity, water use efficiency, and technological quality of sugarcane subjected to differents water regimesAbstract -The objective of this work was to assess stalk and sugar yield, water use efficiency, and technological attributes of five early maturing and six medium to late maturing sugarcane varieties with no irrigation (1,141.4 mm) and under full irrigation (1,396.6 mm). A randomized complete block design, with four replicates, was used. Stalk yield for varieties RB92579, RB72454, and SP81-3250 showed gains above 180% with irrigation. Irrigation increased sugar yield in more than 200% in the RB92579 and RB943365 varieties. Full irrigation provided greater water use efficiency, producing, in average, 70.2 kg ha -1 mm -1 more stalks than under no irrigation. Except for the varieties RB72454, RB763710, and RB943365, there were no differences regarding technological attributes between full irrigation and no irrigation. The medium to late maturing varieties RB92579 and SP81-3250 have higher stalk and sugar yield and better water use efficiency, and are recommended for studies on sugarcane response to irrigation.

Stalk yield of sugarcane cultivars under different water regimes by subsurface drip irrigation

“…In percent terms, the mean TWD applied in the WS regime (1,510 mm) was only 24.4% higher than that applied in the WD regime (1,213.7 mm). These TWD values were lower than those recommended for 12-month-old sugarcane (1,500 to 2,000 mm) (Silva et al, 2014), a reflex of the better water application efficiency of the subsurface drip irrigation (Oliveira et al, 2011).…”

“…The joint analysis of the TCH data revealed that there was no significant interaction (p > 0.05) between the periods, water regimes and cultivars, indicating that the interannual variability of the imposed WRs was not able to promote alteration in the productive performance of the evaluated cultivars (Gava et al, 2011;Oliveira et al, 2011). The TCH of the cultivars showed significant interaction (p < 0.05) of periods versus water regimes (Figure 2A), periods versus cultivars ( Figure 2B) and water regimes versus cultivars ( Figure 2C), a reflex of the different application of the WRs in each cropping season.…”

“…Oliveira et al (2011) also found superior performance of TCH for the cultivars RB92579 (255.6 Mg ha -1 ) and RB72454 (191.6 Mg ha -1 ), in cultivation under conventional big gun sprinkler irrigation (total water depth of 1,396.6 mm), plant-cane cycle and full irrigation, under the conditions of soil (dystrophic Yellow Argisol) and climate (rainy tropical) of Carpina-PE.…”

“…Studies conducted in different production environments have demonstrated increment in the stalk yield of sugarcane genotypes in response to irrigation (Carvalho et al, 2009;Gava et al, 2011;Oliveira et al, 2011;Macêdo et al, 2012;Silva et al, 2014). However, for the genotype-environment interaction, it is crucial to conduct tests aiming at the expression of the productive potential of the sugarcane cultivars in different water regimes and production environments (Silva et al, 2008).…”

Water productivity for sugar and biomass of sugarcane varieties

“…Unlike this experiment, Oliveira et al (2011) observed increasing WP values when the crop was fully irrigated. These authors investigated eleven different sugarcane varieties and observed a water-use efficiency of 7.01 kg m -3 in rainfed and of 14.03 kg m -3 irrigated plants.…”