Utilization of tomato rootstock as a strategy to increase crop performance under suboptimal soil temperatures
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Authors
Bristow, Steven Tyler
Issue Date
2020
Type
Thesis
Language
Keywords
grafting , mineral nutrition , root anatomy , root hydraulic conductivity , Solanum lycopersicum , stomatal conductance
Alternative Title
Abstract
Suboptimal soil temperatures (SST) reduce root establishment, growth, nutrient and water uptake thus impeding shoot growth and delaying harvests. Growers in northern latitudes and higher elevations such as in northern Nevada can encounter adequate air temperatures during the day but production can still be challenged by SST (≤20 °C) for summer crops. To adapt and optimize warm-vegetable production early in the season, growers may be able to rely on improved performance by using chilling-tolerant rootstocks. However, information on which rootstocks and how they can improve performance does not exist. We evaluated four commercial tomato rootstocks (Estamino, Maxifort, RST-04-106T and Supernatural) grafted with a common scion and the non-grafted scion/cultivar (BHN-589) under prolonged chilling stress. Several root and shoot physiological traits were evaluated regarding plant performance, water and nutrient uptake. Exposure to SST reduced plant water uptake as indicated by reduced root hydraulic conductivity (Lp) and conductance, stomatal conductance (gs¬¬), and plant biomass. Reduced Lp was partially explained by increased cortex area of primary roots under SST. While all grafted phenotypes demonstrated higher gs than the non-grafted cultivar under optimal soil temperatures, only two grafted phenotypes maintained higher gs under SST. All phenotypes showed greater reductions in shoot biomass than root biomass resulting in increased root-to-shoot ratios. In the hoop houses, most grafted phenotypes increased early canopy cover, NDVI, shoot biomass, and fruit yield. We demonstrate that some commercial rootstocks possess traits that can improve plant functions and contribute towards earlier plant establishment and improved performance under the SST conditions present in northern Nevada.