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Extension Spotlight

Once they are eligible for harvest based on accepted criteria, many vegetables are picked as labor, weather, market and other conditions dictate.

Many criteria are used to determine if a crop is eligible for harvest and marketing. Size, shape, color, firmness and weight are among the most commonly used -- they are mostly objective, can be assessed quickly and reliably and they influence “eye appeal” during marketing and distribution. Many growers tend to use one or more of these objective criteria alone to determine if a crop is ready to harvest and market.

That said, other, more subjective criteria such as flavor and nutrient content may also be useful. Of these, components of flavor may be the most easily, inexpensively and reliably evaluated on farms using °Brix values.

°Brix is a unit 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 tend to be the most abundant soluble solid in these units; therefore, sugars tend to contribute most significantly to vegetable °Brix values.

The most abundant sugar in many crops is sucrose. It is in the class of sugars that can contribute to the level of sweetness that is perceived when a product is eaten. MANY compounds contribute to flavor so there is NO guarantee that higher °Brix readings will result in the product tasting sweeter. In fact, some Brassica crops tend to have much higher °Brix levels than other sweeter-tasting vegetables (the sweetness based on sugar content can be masked by other stronger-tasting compounds in the vegetable). Still, °Brix values have become a key bit of information for enterprising growers interested in knowing more about their crop: for example, how varieties and soil and crop management influence soluble solids levels in their crop and how sweet their crop may taste to consumers.

In fact, when obtained and applied correctly, °Brix values can aid in variety selection, harvest scheduling, and other aspects of crop production (e.g., irrigation, fertility, and post-harvest management). An overview of the use of °Brix is given in The Ohio State University Fact Sheet HYG-1650-12, Using °Brix as an Indicator of Vegetable Quality by Kleinhenz and Bumgarner. Other Fact Sheets in the same series provide an overview of the use of °Brix and describe how to collect and use °Brix values in specific crops. Two videos are also available as training tools: What is Brix anyway? and How to Take Brix Measurements. Reference values are available in government and scientific reports and other documents. These resources are a straightforward and comprehensive introduction to measuring and using °Brix values.

In Spring-Fall 2011, we cooperated with eleven growers throughout Ohio in measuring °Brix in twenty-four different crops. The numbers were surprising. °Brix values varied widely within crops (across farms and harvests), suggesting that this aspect of crop quality differs significantly for individual crops farm to farm and picking to picking. Based on the results of that and follow-up tests, we are confident that, with sufficient calibration, growers who routinely measure °Brix are more prepared to select varieties and production practices that result in crops with higher °Brix values.
 

 

Lab Happenings

 
The VPSL is currently focused on a range of research projects in the areas of quality, fertility management and vegetable grafting. It also continues to contribute to the domestication and commercialization of Taraxacum kok-saghyz (TKS), a plant known for its production of natural rubber and inulin, and to the development of superior potato varieties.
 
Brix is among the most commonly measured characteristics of fruits and vegetables. However, the optimal use of Brix values is rarely obvious. In 2012, the VPSL developed four fact sheets regarding Brix values (i.e., tips for obtaining and using them). It continues to study relationships between vegetable crop management and Brix, as one step in enhancing overall crop quality.  
 
A statewide effort to document the status of vegetable soils based on soil test results is underway. The VPSL is working with Ohio vegetable growers to compile a database of soil test results that will guide future research and extension activities. This work is supported in part by the Ohio Vegetable and Small Fruit Research and Development Program. Contact the VPSL for more information. Also ask about our participation in collaborative efforts to develop algae-based biofertilizers and to evaluate other commercial natural products reported to enhance vegetable crop growth and yield.
 
Grafting studies are underway in open field, high tunnel and controlled environment settings and in conventional and organic production systems. Studies involving tomato, pepper, watermelon and cantaloupe are located at the OARDC and on area farms. The goal of this work is to maximize the performance of grafted plants from preparation through harvest. This work is supported in part by the USDA-NIFA Specialty Crops Research Initiative. A new vegetable grafting listserve is now available. Click here to join.
 
North America has a huge and growing appetite for natural rubber and inulin. TKS has the potential to supply both feedstocks, limiting the amounts that are currently imported. Therefore, commercial production and processing of TKS in Ohio and large tracts of the northern U.S. would strengthen on- and off-farm business there. With its PENRA partners, the VPSL continues to develop TKS germplasm and to develop seeding methods that maximize TKS stand establishment. Seed harvest in 2013 is nearly complete and root harvest is approaching quickly. Where TKS is not yet a commercial crop, potato is an enormously important one throughout the Eastern U.S. The VPSL is cooperating with potato breeding programs in ME, NY, NC and the USDA in the evaluation of more than 100 varieties and pre-commercial lines.
 
Extension activities are also important to the VPSL. Recently, it has contributed to tours of commercial and research farms, delivered production workshops, addressed individual grower questions, participated in industry roundtables, initiated the development of fall-winter programs, and authored publications. If you have not yet seen version 2 of our grafting guide and would like a copy, click here.