Testing performance of tobacco varieties in water stress conditions
Increasing climate instability could lead to local agricultural constraints, presenting a risk for volumes and quality of tobacco supply. Selecting and breeding tobacco varieties for the ability to perform in unfavourable water conditions becomes a pressing need. Today, in addition to the compilation of crop performance over multiple years in relation to climatic data, there is a need for tools to select the best drought-accommodating germplasm in a consistent, reliable manner. We aimed at identifying and validating a tool for reliable tobacco performance testing under defined water stress conditions, and we scored a panel of eight commercial Virginia varieties for drought tolerance. Three different approaches were tested: 1) tailored classical greenhouse conditions, 2) PhenoFab digital phenotyping (Keygene, Wagenigen, NL), 3) Rainout system (LandLab, Quinto Vicentino, IT). The water regime was set to mimic drought episodes that can occur in specific areas. Depending on the system, different crop parameters were monitored, such as growth dynamics, final yield, and quality. The metrics and the absolute differences vary from one approach to the other. For instance, the PVH2254 variety displayed the highest Water Use Efficiency index in digital phenotyping, and the PVH2299 variety produced 11 % more cured biomass compared to the K326 variety in Rainout experiments. Interestingly, the ranking for drought tolerance in the different varieties within the different experiments is consistent. For instance, K346 was identified as the most sensitive to water stress conditions, and some tested hybrids showed higher drought tolerance than K326. As result of the study, we show that it is possible to obtain promising performance trends in the different selected test systems. Moving forward, these tools can provide information allowing a reasoned management of the environmental factors.