Growing Magazine - November, 2012

SOUTH FEATURES

Breeding Chile Plants for Mechanical Harvesting

By Nancy Riggs

Plant breeding is an intense process, and progress can be slow. Chile breeding has long been a significant undertaking at New Mexico State University. The New Mexican green chile has a long history, pioneered by Dr. Fabian Garcia, who began a chile improvement program at New Mexico State University (NMSU) in 1888 and officially released the New Mexico No. 9 in 1913.


Green chile varieties have now been narrowed down to 20 from 700 through extensive trials.
PHOTOS COURTESY OF STEPHANIE WALKER, NMSU.

Prior to Garcia's work, no genetic control was known to manage the heat of green chiles. Garcia's release was important because it introduced the New Mexico pod type, now also known as long green. 'Anaheim' and 'Big Jim' are cultivars of the New Mexico pod type. Though grown widely in California, the seed for 'Anaheim' originated in New Mexico. Chile has been a mainstay of New Mexico agriculture and represents about $325 million of the state's economy.

Chile industry professionals and the New Mexico Chile Association identified mechanical harvesting of chiles as a must in order for the New Mexico chile industry to survive. While most red chile is now mechanically harvested, green chile is harvested exclusively by hand. Many of the more tender green chile varieties currently available are subject to breakage with the use of mechanical harvesting, and destemming is also an issue. Encouraging results from NMSU variety development research indicate that a cultivar with features that make it friendly to mechanical harvesting may be on the horizon.

"We intensified efforts in 2008 on developing a green chile variety for mechanical harvesting as part of the systems approach to mechanical harvesting," said Dr. Stephanie Walker. NMSU, a land-grant college, has taken a lead role in developing a workable approach to mechanical harvesting, with breeding research a main component, continuing the long tradition of NMSU's contributions to the chile pepper industry. Walker, NMSU Extension vegetable specialist, completed graduate work at NMSU under Dr. Paul Bosland, known as the "chileman." Bosland was co-founder of NMSU's Chile Pepper Institute and co-chairman of the International Chile Pepper Conference, the world's largest conference devoted to chile peppers. Walker has conducted research in red chiles and is now focusing her studies on green chiles for mechanical harvesting.

Harvest labor costs for hand-harvested chiles in the U.S. are about 50 percent of production costs. Harvest costs decrease to about 10 percent of production costs with machine harvesting, according to the USDA Agricultural Research Service. "With the very short window for harvest, labor is required at precise times," Walker said. "Most New Mexico growers aren't able to use federal labor programs. The smaller growers can't offer work to the crews over the periods of time required."

NMSU is looking at mechanical harvesting needs through a systems approach. That approach includes development of an efficient destemmer. A model developed by NMSU is currently in field trials. Extensive trials with harvesting equipment continue, and trials of the Yung-Etgar machine with a double helix are encouraging. The Yung-Etgar machine is used extensively in red chile harvests in Israel, and produced less breakage and less harvested trash in the green chile harvest trials.

Breeding for mechanical harvesting

Walker has selected various plants that exhibit characteristics needed to work well with mechanical harvesting. As with all crops, quality is a primary concern. Breakage or field trash in the harvest reduces the value and can easily make the harvested crop unacceptable. While resistance to breakage is a key point, other elements come into play. "We have to look at the plant architecture, whether it is a concentrated plant set with most of the fruit on the inner part of the plant or more dispersed," Walker said. Plants with the fruit concentrated too much on the interior of the plant are more difficult for the mechanical harvester to harvest.


Stephanie Walker examines green chiles for important characteristics as they mature and turn red.

"Growers stagger plantings to assure that there's a continual supply of green chile for processing plants and fresh market throughout the season," she said. "It currently appears that mechanical harvest of green chile will consist of a once-over harvest, or only one harvesting pass. Therefore, one of our breeding objectives is development of plants that set and mature most of their fruit simultaneously."

Effective destemming of mechanically harvested green chile plants is a major challenge, because stems must be removed from most of the green chile fruit destined for processing. In hand harvesting, experienced pickers are able to pull the green chile from the plant while simultaneously popping off the stem.

"Ideally, a destemmer would pop the stem off in the same way, although a mechanical destemmer that cuts the stem off the chile fruit is also an option," Walker said.

"From a breeding perspective, we need the stem to be protruding, not recessed, regardless of whether the stem is popped out or cut with a blade or other means," she explained. A recessed stem would mean that a top portion of the green chile would have to be cut, thereby reducing the value of the green chile as a fresh market or whole frozen product.

Walker noted that consistently flat, two-locule green chile fruit are essential for effective mechanical destemming. "While environmental impacts can affect the locule formation, there is a genetic component as well, so this trait can be improved through breeding," she said.

"'NuMex Joe E. Parker', from NMSU, and 'Despanado', from Curry Seed & Chile Co., were the top performers in green chile mechanical harvest trials. We found less field loss and less harvested stems and branches with 'NuMex Joe E. Parker'," Walker said.

"'Sandia' was also used as a parent to work toward a large-pod, hot green chile for mechanical harvest. We developed over 700 inbred lines derived from plants selected from the field and strategically crossed in the greenhouse," explained Walker. "We evaluated the lines at both the Los Lunas research center and the Leyendecker Plant Science Research Center near Las Cruces to observe any potential environmental impacts.

"We invited field managers who have a great deal of expertise in chiles to look at the diverse breeding lines. Lines were selected based on overall fruit load, plant habit and fruit characteristics. From the 700 lines evaluated, 60 lines were selected for further analysis. The 60 lines were harvested and evaluated for plant and fruit dimensions, overall yield and fruit quality," she continued. "Following data analysis, the 20 top breeding lines were selected for seed increase. Now we have 20 exceptional lines to advance for replicated trials in three locations." Trials will be located in two commercial growers' fields and at NMSU's Leyendecker Plant Science Research Center.

A quarter century of progress continues

Traditionally, strong emphasis in green chile research has been on developing varieties with consistent heat, or spiciness. That element of green chiles has contributed to its increasing popularity for commercial use. While green chile heat could vary with each dish, which local customers expected, commercial food processors and chain restaurants demanded consistency.


A protruding stem, rather than a recessed stem, is one of the important characteristics to facilitate efficient mechanical destemming.

With NMSU's 1976 release of 'NuMex Big Jim', a large, flavorful green chile, that consistency became available and green chile interest increased. Green chiles are popular fresh market items, and locally they are roasted, peeled and frozen. Processors sell green chiles as canned, chopped chile, and they are used to produce salsas and sauces. Recently, roasted, peeled chiles have gained popularity in Internet sales, offering customers that fresh chile option.

With satisfactory progress in harvesting equipment, destemming prototype machines in commercial trials, and promising results in variety development, mechanical harvesting may be just over the horizon. A private group is working on developing a destemmer that operates differently, and as with previous mechanizations, private development will continue to expand and develop products in response to university research.

Partnerships will continue to offer growers more opportunities to remain competitive in an increasingly difficult environment and provide consumers with quality products.

Nancy Riggs is a freelance writer. She resides in Mount Zion, Ill.