Showing posts with label plants. Show all posts
Showing posts with label plants. Show all posts

Sunday, April 19, 2009

popcorn on the cob


It's a perfect time to start a science activity! Have you ever wondered where popcorn comes from, other than the back of your cupboard?
Try this:
1. Take some unpopped, popcorn kernels from a jar. Don't use the kind found in a microwave bag.
2. Fold a piece of paper towelling in half and place the kernels between the folds.
3. Lightly damped the towelling with water and put the towelling and popcorn kernels in a plastic zip lock bag. Seal the bag and leave in a warm place, like a window ledge.
4. When the kernels sprout, and tiny thread-like hairs appear in the bottom of the kernels, remove the kernels from the zip-lock bag.
5. Plant each sprouted kernel in a small pot and leave in a warm spot indoors until the plant is several inches high.
6. Transplant the popcorn plants into large pots or in a south facing spot in the garden. Watch over the summer as the plant grows and corn cobs appear on the plant.
7. Harvest the corn when the cobs are about 6 inches in length. The corn on the cob will look like popcorn and not sweet corn on the cob, the kind you boil and eat with butter.
8. You can pull off the husks (the covering from the corn) and have an adult microwave the popcorn right on the cob.

Wednesday, April 8, 2009

Chocolate Eggs under Threat from Witches Broom

This is a very timely article from the New Scientist web site. It was written by Debora Mackenzie. Besides, the title alone makes the article a must read!

Chocolate eggs under growing threat from witches' broom
07 April 2009 by Debora MacKenzie
Magazine issue 2703. Subscribe and get 4 free issues.
IT'S chocolate egg season again, and sales of the pagan and Christian symbols of rebirth are as strong as ever. But the hunt for Easter eggs may truly be on next year, because chocolate trees are in increasing trouble.
Chocolate is made from the fermented, roasted seeds of the cacao tree. The cacao swollen shoot virus (CSSV) can kill the trees, and threatens to slash this year's spring crop by a third in the world's biggest producer, Ivory Coast. Meanwhile a fungus called witches' broom is doing the same in Brazil. Now researchers are racing to sequence the cacao genome and find genes that can resist CSSV.
Cacao trees are native to the Amazon rainforest, but west Africa produces 70 per cent of the world's cocoa, virtually all on tiny, impoverished farms. In recent years, demand for chocolate has mushroomed. The farmers cannot afford expensive fertiliser so they boost production by planting more cacao trees over a greater area. That means cutting down other trees that normally grow between cacao crops, which also replicate their rainforest origins and give them the protective shade they prefer.
"Increasingly cacao is grown almost as a monoculture," says Paul Hadley of the University of Reading, UK. That promotes the spread of disease, as does the trend towards growing the trees in drier regions - water-stressed cacao trees are less able to fight off disease.
In recent years, CSSV has become an increasingly serious problem in Ivory Coast. The virus originated in native African trees, in which it is endemic, and is spread by common mealy bugs, so it can't be avoided. The only defence until now has been to destroy millions of infected cacao trees to create disease firewalls. Yaw Adu-Ampomah and colleagues at the Cacao Research Institute of Ghana (CRIG) have found cacao varieties in Africa that partially resist the killer virus, and they are trying to breed more resistant strains.
But progress is slow. New genetic stock brought over from South America must be quarantined for two years before going to Africa, and experimental crosses take three years to grow before researchers can test for CSSV resistance.
Ray Schnell and colleagues at the US Department of Agriculture lab in Miami, Florida, are trying to speed things up. "We're mapping genes for resistance to CSSV now," he says. "It will all be a lot easier in a few years when we've sequenced the cacao genome."
If they can link particular DNA sequences with CSSV resistance, they hope to use them to make a testing kit so researchers in Africa can screen experimental crosses and plant only resistant seedlings. The CRIG is already using such a test to combat a fungal cacao disease called black pod.