Crop yield and price

Biologically, marketable yield is the product of the total plant mass produced and the fraction of plant mass which constitutes the marketable product. This fraction is called the harvest index. During production, plants may not produce as much as they could under the given physical conditions, because, for instance, insects feed on them or fungi reduce their photosynthetic area. The proportion of plant mass protected from getting lost can be considered the protection efficiency which, together with the potential plant mass, determines the total plant mass.

Since light is the energy source of plant growth and usually the main constraint to plant growth, potential plant mass can be described as the product of light intercepted by the plant and light use efficiency. It should be noted however that “more light = more yield” is not an accurate equation.

Prices for vegetables depend on various factors with season and quality of the produce being of foremost importance. We can break down “quality”  into “external quality” and “internal quality”, which are further subdivided into, for example, “look” smell” “taste” and “nutrients” or chemical residues. The various quality and yield traits may be inconsistent with each other. Taste may conflict with yield, external quality with chemical residues. More info about these in the toggle box.

Product quality, season and price

Produce quality is a complex trait depending on many individual plant properties as desired by the consumer or legal definitions. We can distinguish between external and internal quality:

  • External quality describes the shape, look, feel and smell of a fruit product, from simple “beauty” to special shapes and colors. Halloween pumpkins are not bought for their taste but only for their large size, orange color and thick fruit flesh. As such, spending energy on their taste is wasted. Decorative fruits fall into the same category, but most of the time the looks of a fruit are important purchasing criteria. Rich and strong colors which, importantly, need to be the right colors. Tomatoes are red, a cauliflower curd is supposed to be white, and cucumbers should be deep dark green.
  • The shape of a fruit is of great importance as well. Cucumbers, for example, are sold in most supermarkets around the world in large boxes, which are shipped to them from the warehouses where the cucumbers are packed. It is a necessity to fit as many fruits into a box as possible, in order to reduce transport costs. As such curved cucumbers are sorted out, with only the straight ones being shipped. For a deep insight into how the cucumber fruit shape is regulated on a biochemical level [click here](https://www.mdpi.com/2223-7747/9/6/772/htm#:~:text=Cucumber fruit develops from an,3%2C27%2C36].) [Liu et al., 2020]
  • Internal qualities are those that appear during eating or preparation of the produce. These range from taste and nutrients to more specialized qualities like seedless grapes.

Same with the time of sale. Prices are highest when there is high demand and little supply on the market, e.g. in early spring.. At the same time many products are only pushed to the market at a certain time because they cannot be sold around the year, like large orange pumpkins for Halloween. Also keep in mind that the expectation of high price periods might lead other growers to adopt the same strategy, driving prices down again, which has to be weighted in with the possibly higher production costs.