S173 Plants and People - Notes from Study Period 2 - Part 2 of 2

As promised, here's the second part to the study period 2 for this course.

We look at the beginning of food crops and the advent of farming. I won't cover that here as I have written about it before, if you wish, see here.

Crop Improvement
We then look at crop improvement and how by accident of design the early farmers managed to produce a selective breeding programme for the food crops that they were using. This has the following steps:

1. Collection of seed from the most productive and healthiest plants - which are at this stage; wild.
2. Sow this collected seed and over time cultivate the plants.
3. Harvest seed from the best performing cultivated plants.
4. Breed the best performing plants together - these are the plants that have the characteristics you're looking for, for example ease of harvest.

Other characteristics include:

• produce ideal amount of seeds.
• produce ideal size of seeds.
• produce an end produce that can be stored easily (for example over winter) or easily processed.
• ideal growth characteristics that make the plant manageable over its life history. An example being cultivating wheat to have shorter stems which allow for easier harvesting, among other things.
• ideal length of seed dormancy, for example you may want your seed to begin germinating immediately after the harshest weather has passed - rather than wait until the middle of summer, this also requires a high rate of germination.
•  increased resistance to plant pests and diseases.

Looking at the origin of the main food crops that we use leads us to Nikolai Vavilov, a botanist and geneticist. He came up with the idea that each cultivated plant came from a particular place. In this place the greatest variation of its wild relatives can be found. He called these places 'centres of diversity' and 'centres of origin'. For example, cabbage from the Mediterranean, apples from Turkey.

Staple Food Crops
We have staple food crops that provide the main food of a community, being cereals, sugar crops, fruit and veg, for example. We learn that grains, containing approx. 75% starch, 15% protein, 2% fat, along with vitamins such as B and E, should be eaten whole. As white flour is only made from the endosperm (as in the diagrams of part 1), but doesn't contain the fibre-rich bran of the grain's testa or the vitamin-rich germ of the embryo. In rice this is called 'polishing' and can lead to a disease in humans that can lead to death if it is the main food eaten - beriberi - as it lacks vitamin B1.

Non-staple Food Crops
We also grow crops to be used for their oil, for example, sunflower or oilseed rape. The oil can be used in food production or for industrial purposes.

We can derive many benefits from these crops, such as omega-3 fatty acids.

Feeding a growing population
Poor harvests, droughts, floods, and conflicts within a food producing region are all causes of hardships on populations that rely on these sources.

We learn that even with computer modelling, it is difficult to predict how issues, such as climate change, will affect crop production. It is suggested that rising sea levels, due to climate change, will result in 20% of the Nile Delta being lost - an enormous amount when considering that it currently produces 60% of the nation's food supply.

There are many research organisations looking into improved crop production, such as fertilisers, herbicides and pesticides. Along with greener options, such as green manure - growing a crop that is then ploughed back into the soil before the main crop is grown.

Plant Nutrition
There are micronutrients and macronutrients. With 10x the amount of macronutrients required compared to micronutrients.

There are three main macronutrients that plants require:
Nitrogen (N): strong plant foliage.
Phosphorus(P): Growth and development of roots and flowers.
Potassium(K): Overall plant health and fruit development.

I hope you find these notes helpful. See you at the end of Study Period 3!