Broad adaptation of ”improved” varieties is a cornerstone of the Green Revolution. But what does it mean? That a crop variety can grow and is competitive in multiple environments? Or that there is a large homogeneous environment where a particular variety is competitive?
It refers to wide variety of crops which are able to tolerate and survive to various types if environment and be able to produce
I sugget to read the article from Ceccarelli 1989 on wide adaption in euphytica. Article Wide adaptation: How wide?
Let me try to answer by highlighting the two forms of adaption with an example:
When evaluating a set of candidate entries across multiple growing environments (i.e. specific agro-ecologies to that crop) differential responses are excepted. This is referred to as genotype x environment interaction. The trend and extent of this interaction has several implications to the grower and breeder including on selection and recommendation of best adapted variety and suitable production environment(s).
Broadly adapted variety shows better performance across contrasting growing environments or management conditions. Typically, when the environment improves, broadly adapted variety yields proportionally better and stable than others. Whereas a variety with specific adaptation yields relatively better under a specific set of environments only.
Modern varieties are often responsive to improved growing environments and management conditions and can have broad adaption or narrow adaption. Landrace varieties are not artificially bred which are low yielding and less responsive to improved growing environments compared with modern varieties. However, landraces are best adapted to harsh growing conditions and stresses (e.g. drought and heat stress and poor soils) and tolerant to inspect pests, diseases, and weeds. The choice of broadly adapted or narrowly adapted competitive variety is subject to genotype performance, the environment and their interaction.
For instance, see below an antibattery scheme showing mean yield response [tones/hectare] of 4 varieties (A to D) across five contrasting environments (E1 to E5).
Environment ----------------------------------------------------------- Variety E1 E2 E3 E4 E5 _________________________________________________ A 2 2 2 2 2 B 1 4 4 5 6 C 2 4 6 8 10 D 2 5 5 3 2 _________________________________________________ Several questions and answers can be drawn from the above scheme, for instance:
1. Which variety has broader adaptation? Why?
Variety C. Shows high performance across E1 to E5.
2. Which variety has narrow/specific adaptation? Why?
D. Performs relatively better in E2 and E3.
3. Which variety is most likely a landrace? Why?
A. Low yielding and not responsive to the change in environment.
Nice question. I think I chose the first one, "That a crop variety can grow and is competitive in multiple environments." A crop variety changed or improved its characteristics to grow and survive in wide-ranging environments.
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The Green Revolution, because it is intensive, faces, almost everywhere in the world, the limits of water and soil resources, particularly in arid countries. The Challenge is: A new green revolution is more necessary than ever, one that changes the water paradigm. See references within the project:
https://www.researchgate.net/project/The-Holistic-Water-Balance-Blue-Green-Virtual-Water
This issue is also discussed on:
https://www.researchgate.net/post/Water_Footprint_Water_Colors_Blue_Water_Green_Water_Grey_Water_Virtual_Water?_ec=topicPostOverviewAuthoredQuestions&_sg=iBqrYhMeOpt8xH6DTzC_RzqDIMc-ggyWauXMBUWJdhaVGYGv9nHpRG03phkYzMemGhELPunGcyfB8OlP
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