Thursday, July 31, 2008

Plants get sunburn, too

From TODAY, World
Wednesday July 30, 2008

FRESNO (California) — Just like how people damage their skin in the sun, produce can also get nasty burns. That’s why farmers are increasingly applying sunscreen to their crops to prevent skin blistering, heat stress and blemishes.

Sunspots on a Granny Smith apple can mean the difference between the lowest price for juice or the more lucrative fresh fruit market.

As for nuts, buyers last year paid on average 3 cents (5 cents) per 500g more for sunscreenprotected nuts than untreated ones, said grower Ed Lagrutta as he stood in the bed of his Chevy Silverado, inspecting a San Joaquin Valley walnut grove in its second year of sunscreen tests. With yields topping more than 900 kg per 4,000 square metres, it adds up, he said.

Climate change and drought in Australia and California’s Central Valley have meant challenging growing conditions for farmers that are affecting the quality, yields and price of produce.

Sunscreens alleviate at least one worry for farmers, who lose money with each fruit or vegetable that develops sun damage.

Plants react to sun stress like humans. They perspire, — a process called transpiration — which means the more temperatures rise, the more water they need. As drought grips several of the world’s key growing regions, scientists are looking at ways to conserve by helping plants use less.

Liquified clay has been used for years, but now a California company is finding positive results with an SPF 45 product made of multi-crystaline calcium carbonate crystals that are engineered to specifically deflect ultraviolet and infrared light from the plants and trees on which it is sprayed.

The product keeps out the bad light, but lets in the good photosynthesis rays that aid ripening. It has been tested in Australia and Chile, where UV rays affect production, and is in the second year of field tests in California.

Tests show that its immediate impact is increasing yields by diminishing stress and heat-related defects. It also can play a role in water and energy conservation by increasing a plant’s water efficiency. AP
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