January 6, 2011

Pumpin’ Up Pineapples!

Filed under: Adaptation, Agriculture, Plants

Winter is here for most Americans and doesn’t a trip to Hawaii sound perfect over the upcoming months? Sun, beaches, tropical drinks garnished with pineapple, pineapple at breakfast, pineapple on pizza, pineapple on hamburgers… pineapple here, there, and everywhere. Somehow a trip to Hawaii without pineapple just wouldn’t be a trip to Hawaii, would it?

Turns out a little extra carbon dioxide in the air will add to your experience as the extra CO2 boosts productivity of those perfect-with-anything pineapples from our Pacific paradise.

Pineapple is actually an exotic plant that operates in ways shared with very few other plants on the earth. Only two or three percent of plants on our planet are CAM plants that utilize Crassulacean acid metabolism (CAM) for growth. Interestingly, their biochemistry was not recognized as particularly different until 70 years ago. CAM plants are most common in arid environments where water comes at a premium. The most important benefit to the plant is the ability to leave most leaf stomata closed during the day. Being able to keep stomata closed during the hottest and driest part of the day reduces the loss of water through evapotranspiration, allowing CAM plants to grow in environments that would otherwise be far too dry. Most other plants, for example, lose 97% of the water they uptake through the roots to transpiration (mostly during the day)—a high cost avoided by CAM plants.

Most CAM plants look good in the desert (cacti, agaves), but it takes generations of living around them to figure out how they can become a significant part of our diet. Pineapples in Hawaii and cacti in Arizona seem worlds apart, but they share many of the same characteristics include thick skins, few leaves, and prickly defenses.

But unlike cacti and agaves, pineapples seem ready to eat and be part of our Hawaii vacation. Here are some facts about pineapples you might find interesting that we gleaned from around the web. The pineapple is native to Brazil and Paraguay. Columbus introduced them to Spain (he found them in the Caribbean); pineapples became popular among sailors as protection against scurvy. The Spanish introduced the first pineapples to Hawaii. The state is now one of the top pineapple producers in the world, producing one third of the world’s pineapple crop and 60 percent of the world’s canned pineapple. James Dole (a.k.a, the Pineapple King) started his first pineapple plantation in Wahiawa, Hawaii in 1900 and opened his first cannery in 1901. The Del Monte group got into the game shortly thereafter. Hawaii produces over 200,000 tons of pineapple each year, but the production is decreasing as pineapples are now being grown more cheaply in other parts of the world. Pineapples take 18 months to grow, and one cup of pineapple has about 135 calories and 33% of the RDA of Vitamin C.

With our thoughts drifting to Hawaii and our sudden interest in pineapple, we at World Climate Report wondered how pineapple will respond to higher levels of atmospheric carbon dioxide (CO2) and potentially higher temperatures. We quickly found our answer in the Journal of the American Society of Horticultural Science in an article written a few years back by three scientists with the University of ___.? This is a test … (a) Nebraska; (b) Manitoba; (c) Arizona; (d) Hawaii; (e) Maine? Answer is … (d) Hawaii! We suspect you got that one right on the first try? If not, start the essay over and try again.

The three scientists were with the Department of Agronomy and Soil Science in the Department of Botany at the University of Hawaii in Honolulu (how they get anything done in that location is a mystery). Zhu et al. grew 30 pineapple plants in open-top chambers with atmospheric CO2 levels maintained at 330 ppm and 730 ppm over a four month period. The plant dry mass was 146.0 grams per plant at 330 ppm and 180.1 grams at 730 ppm representing a 23.3 percent increase thanks to elevated CO2. The plant leaf area increased from 6,404 cm2 per plant to 6,746 cm2 per plant representing a mere 5.3 percent increase. Have you ever eaten the leaves of pineapple? The dry weight increase is not associated with the leaves but with the main body of the plant! The net assimilation rate (a measure of growth efficiency), the relative growth rate, the stem mass to total mass ratio, and the root mass to total mass ratio all increased in higher CO2 (basically, elevated CO2 produced better plants from top to bottom).

The authors conclude “Our results show that pineapple growth was enhanced after 4 months of exposure to elevated CO2, even with a high day temperature.” Going onward, they state “These data and those obtained previously in controlled environments indicate that even if global warming results in a significant temperature increase in the tropics, dry matter accumulation by pineapple should be significantly enhanced by elevated CO2.”

We have covered no end of agricultural plants, grasslands, and forests in so many essays in the past, and over and over, we show that scientists all over the planet are finding that elevated CO2 increases (a) the rate of photosynthesis, (b) the water-use efficiency, (c) overall yield, (d) quality of the yield, (e) resistance to drought, and (f) resistance to pests and other external stresses, including air pollution. But until this essay, we had never considered one of these odd CAM plants. But when we searched around to the answer, we immediately discovered that CAM plants, including pineapple, will share in the biological benefits that come with higher levels of atmospheric CO2.

We’ll raise a piña colada to that one!


Zhu, J., Bartholomew, D.P. and Goldstein, G. 1997. Effect of elevated carbon dioxide on the growth and physiological responses of pineapple, a species with crassulacean acid metabolism. Journal of the American Society of Horticultural Science, 122, 233-237.

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