Crop quality is assessed using many objective and subjective criteria. With important exceptions, subjective metrics such as flavor, texture, and aroma tend to be secondary in scheduling harvest (compared to, for example, labor, weather conditions, and crop size, shape, color, and weight). However, sensory properties must meet or exceed accepted thresholds for marketing reasons. Therefore, a lot of attention has been directed to understanding how genetics (G) and environment (E) influence important “sensory”-oriented properties of vegetable crops. Outcomes of these investigations can have profound effects on growers and industries. They can also help explain GxE effects on various aspects of crop physiology.

°Brix values are used to express the level of soluble solids in a solution. Sugars, pectins, organic acids, and amino acids are the most prevalent soluble solids in the marketable unit of most vegetable crops. Sugars (especially sucrose) tend to be the most abundant soluble solid in these units and, therefore, they contribute greatly to vegetable °Brix values.

Given their relationship to gross carbon status and product flavor, °Brix values interest applied vegetable crop scientists and industry professionals. Moreover, °Brix can be measured reliably and inexpensively in field, greenhouse and lab settings and with fresh or preserved (e.g., frozen then thawed) samples. Research and industry teams worldwide continue to record °Brix values as a function of numerous genetic and environmental factors.

For example, Helyes and others at the Szent Istvan University and National Food Institute for Food Safety and Nutrition in Hungary concluded that °Brix values in tomato (variety Lemance F₁, an indeterminate round-type fresh market tomato) can be closely related to stage of maturity. The highest °Brix values were recorded at the deep red stage. The team also demonstrated that °Brix levels can be positively related to fruit carbohydrate and lycopene content, other important quality traits of tomato.

Dufault and colleagues at Clemson University set out to determine if melon planting seasons could be extended beyond accepted dates. Mindful that sweetness is an important component of melon quality and that °Brix values are associated with consumer perceptions of sweetness, the team measured °Brix in numerous fruit taken from plots representing a range of planting dates. They concluded that earlier, cooler planting dates can allow for a growing season resulting in melons with desirable °Brix values.

Also, working in Ohio, Bumgarner and Kleinhenz (unpublished) cooperated with eleven growers in measuring °Brix in twenty-four different crops throughout Spring-Fall in 2011. Wide variation in °Brix values within crops (across farms and harvests) further demonstrated that °Brix values respond to genetics and environment and that, with sufficient calibration, can be used to optimize GxE combinations within crops and farms.