I am a social scientist now working with potato growing farmers and while discussing with them on their perceived pros and cons of dehaulming, farmers reasoned that cutting the leaf away would expose the tuber (through sun-cracked land) to direct sunlight turning the tuber greenish/blackish, which they claim is not a good attribute in the market. So do you think the biomass can prevent exposure to sun light particularly in tropical areas, and what would be the scientific explanation to the greenness/ blackness? thanks a bunch!
The green colour on potatoes exposed to light comes from the chlorophyll they produce, additionally they produce the toxin Solanin, which can be harmful to humans. So you definitely do not want greening of potatoes, as their value declines. In Northern Europe, where I grew up, potatoes were sprayed with a herbicide every autum shortly before harvest. They do that to make harvesting easier. The growth is stopped when the leaves die, but the potoatoes are not exposed to light as the farmers grow them in dams and heap earth on them during the growth phase as well. Also, in Northern Europe the intensity of the sunlight is very not high in autum. So it really depends what other cultivation methods are employed and how moist it is so the soil does not crack (also no problem in most parts of Northern Europe).
thank you Freinderike. Another expert also mentioned about the Solanin effect which shows farmers observation is inline with what the science has to say. I will further dig in as to how experts, particularly working in the tropics, deal with this problem when they advice dehaulming as a useful (disease) management practice.
The main reason for the light intensity and exposure long time to light,
the best
Dr Ali
"Earthing up" the potatoes should also be possible in the Tropics, it can easily be done by hand if no machinery is available. You could also use mulching with organic matter. Even if dehaulming might reduce disease, it could also spread it, especially if the tubers are later used for seed potatoes. As you cut the leaves, the knive is not sterilised between plants and disease vectors can travel down the open wound into the tubers. While this would not make much difference, if the potato is harvested and consumed straight away, it coud impact seed stock negatively.
Friederike, than you so much im learning a lot from your insightful discussion
Ya absolutely... cutting of the leaf away would expose the tuber (through sun-cracked land) to direct sunlight and tuber can turn the greenish/blackish, is not a good attribute in the market. Green indicates an increase in the presence of glycoalkaloids, in potato, the substance "solanine". When the potato greens, solanine increases to potentially dangerous levels. Increased solanine levels are responsible for the bitter taste in potatoes after being cooked. and it may results sterlity in man.
Ya absolutely... cutting of the leaf away would expose the tuber (through sun-cracked land) to direct sunlight and tuber can turn the greenish/blackish, is not a good attribute in the market. Green indicates an increase in the presence of glycoalkaloids, in potato, the substance "solanine". When the potato greens, solanine increases to potentially dangerous levels. Increased solanine levels are responsible for the bitter taste in potatoes after being cooked. and it may results sterlity in man.
thank you Gajendra, your opinion is consistent with the rest of the experts
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