By the time you read this, winter will be heading toward its end, either by crawling along slowly or by happily retreating so that the sun can finally make its triumphant return. That means it is almost time for another planting season – but for now, we are still often constrained by waiting for the seasons to change.
One group of scientists is currently working on a project that might give us humans an advantage over waiting for Mother Nature to make her move. Let’s look at plasmas – the “fourth state of matter,” the hot, ionized gases can also be found in lightning strikes, the hearts of stars and old neon signs.
In Saudi Arabia, a team of scientists at Jazan University are using space-age technology to induce the sprouting of “sleeping” grapevines. This could mean a way to extend the cultivation of crops that normally only thrive in temperate zones to warmer regions of the planet. Crops like grapes, peaches, berries and flower bulbs all go dormant during the winter, sleeping through the seasonal cold before they resume growing, flowering and fruiting again. In milder climates, plants often do not receive enough chilling time. Growth time is unsynchronized, with some plants budding weeks before others, and this can make it costlier for growers to provide proper care – especially when it comes to pest control, labor costs and lower yields. The scientists are using plasmas to “wake up” the grapevines that are sleeping longer than their peers.
The work of horticulturist Habib Khemira, plasma physicist Zaka-ul-Islam Mujahid and plant physiologist Taieb Tounekti may help to extend the cultivation of fruit crops and ornamental plants native to temperate climates to parts of the world where winters are milder, including the southern half of the U.S. It may also mitigate the problems posed by rising temperatures due to climate change. “Artificial methods to release dormancy are expected to become more important in the near future due to global warming,” said Mujahid.
Plants sense the cold of winter and keep track of freezing days. When enough of those cold days occur, the plants respond by increasing their metabolic processes which leads to bud break and shoot growth when the warmer days of spring arrive. When plants grow in regions with milder winters, however, they may not receive enough chilling to release their buds on time. One of the biggest challenges of modern farming is finding ways to push the maximum number of buds on plants to grow, to flower and to bear fruit all at the same time.
Plasma exposure causes an oxidative stress within the plant, the exact same signal from cold in the cells of dormant plants to which the buds respond by awakening. In treating grape buds with plasmas, the researchers discovered they could release the plant’s dormancy – much quicker than the weather can and more safely than spraying the crops with chemicals to induce the same reaction.
“Some of the results from our first successful experiment were phenomenal, and we could not believe it was true,” Mujahid said. Just a few minutes of plasma treatment on buds that never saw cold weather allowed the plants to achieve similar, if not better, bud break as control plants that experienced optimal cold conditions (60 days of exposure to temperatures about 40 degrees Fahrenheit) did. Note that although the method worked well in the laboratory, it still needs to be field tested.
Whether the plasma approach to treating dormant buds takes off depends on several things, including whether it would work effectively in the field as well as it did in the laboratory. It needs to be tested on crops other than grapes, and the cost of the equipment also needs to be taken into consideration.
“There is still a lot of work to test the effectiveness and feasibility,” Mujahid said. “We are in the process of figuring out the proper parameters to take it to the field but it could be in use within just a few years.”