Tomatoes are one of the most important crops in fresh market and processing industries. Due to fluctuating environment, plant diseases for instance, the production of tomatoes faces problems in both physiological growth and fruit morphology.
In our study, we found that management practices (e.g. grafting) and environmental variation (across locations) affected both tomato physiology and fruit morphology.
In the first study, grafting was found to affect biomass, leaf nutrient levels, and it also seemed to affect disease incidence, α-tomatine level and slightly impacted microbial community structure. Fresh and dry weight biomass of shoots of grafted plants tended to be less than ungrafted plants; however, differences were minimal in later phase of growth. Cross-grafted plants also had more leaf nutrient levels such as P, Ca and B in one or more rootstocks. α-tomatine, one disease resistance related compound in tomato leaves, also seemed to be higher in self-grafted plants. Although no significant differences were found, disease incidence of self-grafted plants tended to be less than the ungrafted plants. Grafting effects on tomato rhizosphere microbes and the contribution to disease resistance were also evaluated. Four 16S and three ITS TRFs (Terminal Restriction Fragments) were found significantly different in abundance between self-grafted and ungrafted plants. Two ITS TRFs were found significantly different in abundance between cross-grafted and ungrafted plants. In general, grafting affected tomato scion physiology and tended to reduced disease incidence, though this may be related to the small noted changes in microbial community structure.
Environment impact in tomato fruit shape was evaluated in the second study. Variations in shape characteristics of 48 cultivars grown in three different locations (i.e. OH, NC, and NY) were investigated. Both cultivar and growing environment affected the relative proportion of malformed (MAL) fruit number and weight that developed on the plants. Environment had a more profound effect on malformed than True-to-type fruits. Significant variation in the overall shape of True-to-type (TT) fruits due to the growing environment was found in 31% of the tested cultivars. The magnitude of these effects ranged from 9% to 59% for the attributes fruit shape index external II (FSI) and/or locule number (LN). Fruit shape genes typically had a more significant effect on the FSI of TT fruits than environment. Environment also had a significant impact on FSI and LN of the group with the ovate mutation. Besides FSI and LN, nine other fruit morphology attributes were sensitive to environment in different ways among various shape categories. These data demonstrated genotype, environment and their interaction greatly affected tomato fruit shape.
Unfavorable environment and disease problems are important in tomato production, either in tomato plant physiology or fruit shape. Study of grafting effects on physiology and associated microbial community provided an insight of investigation in tomato disease resistance and tomato physiology. A thorough investigation of genotype, environment and their interaction was also performed and sensitive tomato cultivars/groups to environment were proposed. These investigations in both management and environment provided a better understanding in tomato production improvement of development and disease resistance.