Dias, Henrique Boriolo, Inman-Bamber, Geoff, Sentelhas, Paulo Cesar, Everingham, Yvette, Bermejo, Rodrigo, and Christodoulou, Diomedes (2021) High-yielding sugarcane in tropical Brazil - integrating field experimentation and modelling approach for assessing variety performances. Field Crops Research, 274. 108323.

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Abstract

Aiming to gain an understanding of how the genotype × environment × management (G×E×M) interaction influences the yield accumulation by elite sugarcane varieties in Brazil, a large dataset from field plot experiments carried out in two tropical sites (Guadalupe, 6.8 °S; São Romão, 16.4 °S) involving distinct planting dates, varieties and harvest ages, was analysed with statistical techniques and with the APSIM-Sugar model.

Radiation use efficiency (RUE) was determined via a series of regressions and employed in an analysis of variance to investigate site, seasonal, developmental, and varietal differences. Outstanding yields were achieved at both sites. RUE declined as the crop progressed, confirming previous observations on declining RUE with age, known as the reduced growth phenomenon (RGP). RUE was always greater at Guadalupe than São Romão, evidencing that Guadalupe is a more suitable environment for sugarcane production, favoured by higher air temperatures during crop establishment and canopy formation. Varietal differences in RUE appeared only after the early developmental stage, and the observed growth slowdown with age was consistent across the two experimental sites, indicating that RGP is a varietal trait that should be considered for high-yielding environments.

The process-based APSIM-Sugar model was set up with recently determined canopy traits and a new RGP feature based on leaf appearance. RGP parameters were obtained for each variety and site through calibration. The calibrated model was accurate to account for yield accumulation by the varieties in both experiments. The new parameters were evaluated with independent datasets from other local experiments at each tropical site as well as from published rainfed experiments in sub-tropical Southeast Brazil. Independent verification of the RGP traits added confidence in the new way of dealing with RGP based on leaf stage. The G×E×M interaction on yield accumulation can now be explored more confidently with APSIM-Sugar for the purpose of optimising the choice of varieties, planting dates and harvest ages for sugarcane industries in favourable irrigated lands in tropical Brazil.

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