By Katia MoskvitchTechnology reporter, BBC NewsLovingly turning around a ripening guava, the farmer nods to her husband working nearby.

This elderly couple tending their plantation in Changhua County in southern Taiwan would probably not have looked much out of place decades ago.
But in reality, they are at the forefront of the island's agricultural revolution.
Like many fruit farmers here, Mr Zai-Lang Jiang and Mrs Xiao-Wen Yang have to battle one of guava's biggest enemies - fruit flies.
The larvae of these tiny insects infest ripe fruits, making them unsellable.
Most farmers use traps containing pheromones - chemicals that attract the flies - and then hand-count the dead insects every 10 days.
But Mrs Yang and Mr Jiang have something extra up their sleeve: artificial intelligence.
Laser beams Developed by scientists at National Taiwan University, a small box-like device uses infrared lasers that scan the farm. Every time a fly gets inside and breaks the beam, it gets counted.
The number is radioed to a monitoring station. When a trap counts more than 10 flies in 30 minutes, or when the forecast model predicts a rapid surge in the fly population, it triggers an alert and sends a text message with the warning to farmers' mobile phones.
The alerted farmers will then increase the number of fly traps, wrap up fruits, or - as last resort - use pesticide.
"We've achieved about 90% accuracy," says Dr Chen-Long Chuang, one of the scientists who developed the sensing and forecast technologies.
So far, only a handful of farmers around Taiwan are taking part in the trial, but the researchers aim to expand the project.
"Fruit flies are a common pest in places like California and Latin America, and you can use our device with any kind of fruit farm, it is not limited to guava," says Dr Chuang.
Intelligent traps are just one example of innovation which has been trickling into the agricultural sector of Taiwan, this island of just 23 million people, known as a high-tech manufacturing hub.
Agriculture contributes a mere 3% to the island's gross domestic product (GDP), with the rest coming primarily from exports - which explains why farming remains relatively low-tech and many Taiwanese rice farmers still wander barefoot through paddy rice fields.
High-tech orchids But this is slowly changing, says Bao-Ji Chen, Taiwan's minister of agriculture.
He believes the government encourages farmers to use new technologies, and the efforts are paying off. More farmers are turning to what is known as precision farming: determining the exact location where the seed is to be planted with the help of a satellite navigation system.
Keeping up with traditions is one thing, but increasing profits with the use of innovation is quite another, he says, sitting in a room decorated with beautiful orchids.
These flowers mean a lot to the economy of Taiwan - the island produces one third of the world's orchids.
Since 2005, it has been the world's largest orchid exporter, according to the Taiwan Floriculture Exports Association.
And it has achieved this with the help of technology.
Automated greenhouses, for example, have flower beds equipped with wireless sensors that help them "know" when orchids need to be watered and whether the temperature or illumination are right. If something is amiss, the system sends a text message to the farmer.
Right now there is only one such fully automated greenhouse, but Dr Joe-Air Jiang from the National Taiwan University says more and more farmers are now interested in using new technology.
Innovations include gene modification in fish farming to produce fluorescent aquarium fish, fully-computerised indoor farms that cultivate a highly-sought after mushroom, and new methods which help produce perfect "century eggs".
Black eggs A century egg is a delicacy that is usually produced in the south of Taiwan, and I visited a farm there to see how technology has transformed the traditional way of checking the eggshells.
Tap, tap, tap, and a farm worker gently knocks three eggs together.
If there is even the tiniest crack in the shell, she needs to hear it. If she misses it, harmful salmonella could infect the egg.
These eggs are called century eggs, or pidan - they may look ordinary, but underneath the shell there is no regular yolk and white.
Instead, the white is jelly-like and amber-brown and the yolk is smoky-black.
The eggs are not for the faint-hearted; the flavour of ammonia and sulphur was unlike anything I've ever tasted before.
In China and Taiwan, pidan are a delicacy, made by preserving duck or chicken eggs in a saline solution for about a month.
"Manually knocking the eggs together is the way [the quality test] is done traditionally," the farmer tells me.
However, on this farm the centuries-old traditional listening method has been replaced by technology, developed by Prof Ching-Wei Cheng from the National Chung Hsing University.
It's a machine with a conveyor belt and an endless stream of eggs on it.
On its journey, each egg passes through a special acoustic chamber where robotic fingers simulate human ones, delicately tapping the shell all around.
The sounds are then analysed to reveal even the tiniest flaw.
"Without our technology, cracks are easy to miss, and even the best farmer could not check more than about 6,000 eggs a day," says Prof Cheng.
"Our inspection system makes sure that cracks are checked with 98% accuracy, and at a rate of about 50,000 eggs in eight hours."
But despite all the innovation developed by Taiwan's scientists, the government still has an uphill battle to convince more people to actually start using it. After all, the majority of farmers on this tiny island are still using the methods of their great-grandfathers.

bbc.com