Mountain Laurel just about to open on local trails - this was see on Pink Beds Train in Pisgah National Forest

Here, we have another guest article - this time by Amy Goldman, current special advisor to the SSE board.

______________

Desert Sweet Tomatoes: Jewels of the Negev

by Amy Goldman

I first became aware of the tomatoes called “Desert Sweet” (a brand name) several years ago while visiting relatives on a kibbutz(collective farm) in Israel. “Kibbutzniks” (local residents) extolled their virtues. Being a tomato aficionado I had to know more and sought out Yoel DeMalach, the man in charge of the nearby Ramat Negev Desert Agroresearch Center (RANDAC). Yoel has 40 years of experience in growing and breeding vegetables and field crops, specializing in onions, and has taught agriculture at Ben Gurion University in Beer Sheva. He has been intimately involved in the development of Desert Sweet tomatoes and along with his frequent collaborator Dov Pasternak of The Institute for Applied Research at Ben Gurion University, is well known for his research with brackish (slightly salty) water irrigation.

The most distinguishing characteristic of these tomatoes is that they are irrigated almost entirely with brackish water, yet paradoxically they are intensely sweet and delicious. Why use saline, rather than fresh water irrigation, and concomitantly, how does this account for a marked increase in glucose (sugar) content? For the answers to these questions let’s start with a little background information.

“Sweet” or fresh water is scarce in Israel and these water resources are being rapidly depleted. On the other hand the Negev desert, Israel’s arid southern region, has vast reserves of brackish water under is sand dunes. The water pumped from wells over 1000 feet below the desert is 400% more saline than the fresh water from the Sea of Galilee. The task of the RANDAC and other collaborators such as Ben Gurion University and The Volcani Agricultural Center has been to literally “make the desert bloom” using salty water and new approaches to agriculture, eg. xericulture, salinity-genetics. And this they have done to a significant degree, based upon experimentation performed over many years.

The tomato is regarded as a moderately salt-tolerant species and thus was a good candidate for research. In order to minimize damage to both soil and plant tissues caused by brackish water, modern drip-irrigation methods were developed. Changes in protocols were made to maximize results. For example, Israeli scientists found that tomatoes need to be germinated and grown in sweet water until the fourth leaf stage. Jointly with the Volcani Center extensive breeding and selection was, and continues to be done, to identify the most saline-resistant tomato cultivars.

A series of controlled experiments performed by teams of researchers have revealed a wealth of information, which, as an amateur gardener, I am neither entirely capable of understanding nor able to report here in full. Nevertheless, some of the most salient features of the research have involved manipulation of different levels of salinity, including rates and times of application, and of even “plant architecture” (pruning vines to two or three branches). The effects of changing these variables was then determined by looking at tomato yields, growth rates, acidity, electrical conductivity, total dissolved solids, sugar content, taste and fruit size under actual field, screen and hot-house conditions.

The results are in and they are fascinating. Irrigation with brackish water improves the quality of tomato fruit and makes it sweeter. Take this to mean better tasting fruit as judged by “blind” taste testers, sweeter fruits with higher concentrations of sugars, as measured objectively, and less fruit cracking.

Saline irrigation significantly reduces total yields of tomatoes but in some cases increases “marketable” yields of certain types such as cherry tomatoes. Fruit size is significantly decreased. The smaller fruit size accounts for yield decreases as the number of fruit produced is unaffected or actually increased. Irrigation with saline water also results in an increase in the percent of dry matter or total dissolved solids of the fruit. The decreased water content of the fruit presumably accounts for the decreased fruit size and increased percentage of dissolved solids and sugars.

By 1990 Israeli researchers were able to produce high quality fresh market tomatoes using saline irrigation. The “Desert Sweet” designation is actually a brand name applied to a number of tomato varieties bred at the Volcani Institute and grown and irrigated with brackish water in hothouses elsewhere in the Negev. The Desert Sweet project began in 1991 and now these tomatoes are exported and sold worldwide, but only I their glucose levels exceed 200 milligrams per kilogram. If they don’t pass this sugar test they stay in Israel where my mother-in-law can love and enjoy them.

If I’ve piqued your curiosity, and appetite, and you’d like to sample these tomatoes bred specifically for the specialty market, head straight to your nearest gourmet grocery and look in the fruit, not vegetable, section. If you’re in luck you may find Desert Sweets “On” or “Off the Vine” … tell’em Carolyn and Craig sent you. The seeds, on the other hand, are proprietary property and are not available commercially. However, if you live in a desert environment and have been searching for suitable tomato or tomatillo seeds to grow, write or call: Native Seeds/SEARCH, 2509 N. Campbell Ave., #325, Tucson, AZ 85719; phone (602) 327-9123.

Another group assisting the desert dwellers in The Arid Lands Development Foundation, a new non-profit foundation which has opened its doors for the express purpose of promoting dry lands agricultural research and raining projects worldwide, specifically as these have been developed at RANDAC. One of their first projects has involved helping the Hopi people of Arizona to develop and economic base in agriculture. The Foundation, with the assistance of Yoel DeMalach and Dov Pasternak, approached the USDA last year for funds to do an extensive feasibility study. Who knows? We may soon have Hopi-grown peppers and corn in the fruit section as well. For more information write or call: Mr. Sam Hoenig, Executive Director, The Arid Lands Development Foundation, 701 Beta Drive, Suite 27, Cleveland, OH 44143; phone (216) 461-8199.

______________

Lots has changed since Amy wrote this article, but it is great to have her contribution to our newsletter. Enjoy!