Chapter 2 Temperate fruits
by Eike Luedeling, Christine Schmitz, Eduardo Fernandez and Anton Milyaev
2.1 Materials
To prepare for class, please watch the following four videos:
- General concepts (password here)
- Nuts (password here)
- Stone fruits (password here)
- Pome fruits (password here)
As supplementary material, we also offer two videos on sweet cherry bloom and apple varieties recorded by our HortiWood team:
- Apple varieties (password here)
- Sweet cherry bloom (password here)
You need the module password from eCampus to access these files.
2.1.1 Questions
- In a few lines, describe the main difference between the fruit production systems for pome and stone fruits. Link the process occurring inside the fruit and the changes that farmers could see.
- What are the types of sunburn usually observed in apple orchards? How could farmers avoid this problem?
2.2 Instructions
We’ll be going for a walk with you. Depending on weather conditions, the ground may be wet or muddy, and it may be raining/snowing/windy etc. Make sure to dress appropriately!
2.3 Literature for discussion
This week we will discuss the following paper: Kofler et al., 2019. High crop load and low temperature delay the onset of bud initiation in apple. Scientific Reports 9, 17986. Read the paper and discuss the tools that are used to study the mechanism of flower bud induction in apple.
Why is the understanding of the flower induction mechanism of particular importance for temperate fruit production? Please be critical while reading the work and try to find the confirmation of each key point described in the text with the data that is shown in the paper.
2.4 Term paper topics
Integrating agrophotovoltaic systems into orchard management: Can fruit trees and solar power effectively coexist?
Agrophotovoltaics (APV) involves the dual use of agricultural land for both crop production and solar energy generation. In this term paper, you will explore whether fruit tree orchards (such as apples, peaches, or cherries) can successfully coexist with solar panels. Investigate the impact of shading on tree growth, flowering, fruit production, fruit quality, and on the occurrence of pests and diseases. How orchard management practices would need to adapt to optimize both solar and agricultural yields? Consider examples of existing APV projects in orchards and their economic and environmental outcomes. What are the potential advantages and disadvantages of integrating APV into commercial orchards?
Chilling requirements and global warming: Can we adjust photoperiod to compensate for winter chill in plants?
Global warming is reducing the accumulation of chilling temperatures necessary for temperate fruit trees to break dormancy and flower properly. In this paper, you will investigate whether manipulating the photoperiod during the winter months could compensate for a lack of chilling. Review the biological and physiological processes behind photoperiod and dormancy in plants (with focus on fruit trees). Present you literature research on how light manipulation (e.g., shortened or extended daylight exposure, certain light spectra, etc.) might affect dormancy and whether the photoperiod can help adjust, reduce or replace chilling needs.
Influences of spring frost protection on the environment
Frost protection measures are great for reducing yield losses caused by spring frosts. But how do they influence the environment, within the orchard, in the surrounding area? You could also include social influences. Select a few frost protection measures and collect information, e.g. from scientific and practical literature, to give an overview about the side effects of frost protection.
Apple fruit color
For red and bi-colored apple varieties, fruit color is a crucial factor for fruit quality class and marketing. But how do apples get their color? What are the possible reasons for insufficient fruit coloration? And how could farmers improve the fruit coloring? Give a very brief overview of process of fruit coloring and focus your literature research on reasons for missing color and measures to increase the share of red peel color.
Rest breaking strategies in temperate fruit trees
In many warm growing regions of temperate fruits, trees struggle to accumulate sufficient winter chill to break their dormancy. Climate change appears to be aggrevating this problem. Growers are therefore looking for, and in many cases already applying, strategies to artificially promote dormancy release. This term paper reviews the current state of knowledge on strategies for artificial rest-breaking and discusses the challenges and opportunities.