Thursday, March 15, 2012

Sweet Potato

 Fig.1     New sweet potato (Ipomea batatas) plant.

Nostalgic Introduction
If anyone would make a movie about my childhood days in the Philippines, sweet potato (Ipomea batatas) would show up over and over again in the background.  Sweet potato is a must-have crop. The roots are eaten as source of carbohydrates prepared as dessert or snack food.  Although it is nutritious and readily available, it does not have the reputation as a staple food unlike rice (Oryza sativa), corn (Zea mays) and cassava (Manihot esculenta).  As a root crop it has a low acceptance possibly due to its flatulent characteristic.   The young leaves, however, have a better reputation as green vegetable.  They are cooked in stews or prepared as wilted salad.  When wilted (not over-cooked) they taste like spinach.  Believe it or not, some varieties taste better than others.   The vines and the older leaves are used as feeds. 

Growing sweet potato is very easy.  In fact the American expression "Piece of cake", can be translated in Ilocano (my native dialect) as "Kasla agmula ti kamote" meaning "It's like planting sweet potato". There was a time when the roadsides in my barrio (village) were all planted with sweet potatoes.  They were beautiful.  Here on the temperate side of the globe, there is also an increasing popularity of the Ipomea (sweet potato) as an ornamental plant mainly for its foliage.

Fig. 2   Sprouts arising from stored sweet potato roots. (January 31, 2012)

Fig. 3 A clean cut on one side of sweet potato.

Regenerating Storage Organs
Now in my house, away from the barrio where I grew up, sweet potato only shows up on Thanksgiving and Christmas.  A month ago while cleaning my pantry, I was in luck!  I found two large sweet potatoes that were sprouting.  The immediate thought that came to mind was planting material.  They have been sitting there for at least two months.  Sweet potatoes, commonly known in the US as yams, are storage organs where food and moisture abound. Because of that, the cells within the root are kept alive and capable of regeneration - starting a new plant.  This is true for most of the food we eat that come in various forms of storage organs such as bulbs (onions - Allium cepa and garlic - Allium sativum); rhizome (ginger- Zingiber officinale); tubers (potatoes - Solanum tuberosum); and corm (taro - Colocasia esculenta).  All of these examples will regenerate when the right conditions are met.  In the home, the pantry seems favorable enough to initiate new growths on such vegetables.

Fig. 4 Wet paper towel encourages root growth on a sprouting sweet potato.

Conditioning the New Sprouts.
Plants grown in the dark, such as those shown on Fig. 2 are etiolated and lanky. This, however, can be improved by exposing them to diffused light.  What I did was cut one side of the root (Fig. 3) to provide a flat surface that would rest on the wet paper towel on a dish (Fig. 4).  It has been my experience that growth of adventitious roots is enhanced by moisture - so the paper towel was kept wet at all times. 

Fig. 5     One week of exposure to light resulted in healthy-looking sprouts.

Garden-worthy Plantlets.
After eight days of exposure to light, the sprouts showed a significant change in coloration (Fig. 5 and Fig. 2).   The young sprouts begin to produce chlorophyll giving the leaves a green color.  They have grown to be more stocky and strong.  The same principle applies to potato (Solanum tuberosum) seed tubers. When their sprouts are pale, give them some time to get exposed to diffused light before planting them.

The roots  (Fig.5) look like they are ready to meet the soil but I will have to keep them inside for a little bit longer until the temperatures get warm. 

 
The Role of Sweet Potato in Another Country
I invite you to watch this video to see how sweet potato is being used to end hunger in Mozambique.

8 comments:

Christine @ The Gardening Blog said...

Hi Helen - I have a couple of Ipomoea Batas I purchased recently =- the lime green coloured one. I absolutely LOVE it as a foliage plant in my garden, and its so easy!

dona said...

Very interesting Helen! Here in Italy we are no longer used to eat sweet potatoes. Altough my mum always told me that they were eatean during the II world war, when people had to struggle to survive.

Helen Lewis said...

Hi Christine -- Yes, the chartreuse sweet potato has bold and vibrant foliage that contrasts well with so many colors. They are great with addition to a border strip as well as in containers.

Helen Lewis said...

Hi Donna --
It's good to meet you as Donna. I've always known you as La Terrazza. :)

It's rather interesting to know that there is a country that does not eat sweet potato anymore. No wonder I have not encountered any Italian sweet potato dish yet.

Anyway, do you use the ornamental sweet potato in landscaping?

Curbstone Valley Farm said...

Helen, where do you source your sweet potatoes? Are you using store bought? Most here have been treated before arriving at the markets so they don't sprout, thereby increasing their storage life. I've given up trying to source organic slips too, they seem more rare than a goose that lays golden eggs, and most can't be shipped to CA. I'd love to grow some, if I can find some.

HELENE said...

Hi Helen, I am of Norwegian origin, but have lived in London for 13 years. I had never eaten sweet potatoes until I moved to UK, but now I buy them regularly, mostly making mash with herbs of them. They are readily available in any supermarket. Would love to grow them but my tiny garden has no room for vegetables. This is my first visit to your blog, will come back for a second helping some other time :-)

Helen Lewis said...

Hi Clare - I like your comparison of the rarity of organic slips with the goose that lays the golden egg with . :) I got my sweet potatoes from Raley's Grocery store. Given enough time in storage, they seem to sprout without any problem. The sprout inhibitor wears off after some time, I guess.

Helen Lewis said...

Hi Helene -- Thanks for visiting my blog. The desire to grow exotic plants is understandable but sometimes we just have to prioritize. I would think that gardening in England is fun. It is so dry where I live that everything is irrigated almost throughout the year.

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