Given the success of protective crop nets to fight harsh weather in Germany, Italy and Spain, Dr. Richard Bastías is promoting the technique to lend a helping hand to Chilean agriculture.

The trend of using crop nets arose in Europe between 2008 and 2009 to address the effects of climate change and prevent cold-weather damage.

While finishing his doctorate in Italy, Universidad de Concepción's Dr. Bastías first witnessed the applicability of both anti-hail nets and colored nets that filter light to prevent sun damage to fruits such as apples and peaches.

"Lately, fruit is facing a lot of risk from sleet. There are zones in Germany, northern Italy and Spain that have had a lot hail storms in apple plantations. Because of this, most new apple orchards are covered in nets. In other words, it's not worth it to invest in an orchard that's not covered in nets," he said.

The researcher brought the technique specifically to Chile's VII (Maule) region and began testing this year. His main goal starting off was to find the impact the nets had on sun damage.

"There are new plantations where they are considering the implementation of structures to hang mesh for sun control. For more sensitive varieties like Fuji and Pink Lady, 40 to 50% of production can be lost without fruit protection," he explained.

"In addition, new varieties we've introduced are very sensitive to radiative and thermal stress. They show a lot of postharvest disorders associated with extreme temperatures. Because of this, there is considerable interest in planting toward the south."

Due to climate change, Chilean production zones have been moving further south. A few years back, the Metropolitan and VI (O'Higgins) regions led production. Now the VII (Maule) region has taken the top spot with trends heading toward the VIII (Bío Bío) and IX (Araucanía) regions even further south.

According to Dr. Bastías, 65% of apple plantation growth has occurred in Bío Bío and the Araucanía.

"One would expect that by moving plantations further south, sun damage would be lower due to colder conditions. But reality has shown that it has not gone down. Today's plantations burn with the same intensity because temperatures have been rising in summer," he said.

"In Angol, for example, we have recorded up to 37°C (98.6°F). So with these thermal conditions and radiation, Chile always exceeds normal conditions found elsewhere. The fruit still burns."

Experimentation and expected results

Dr. Bastías commented that work began with traditional nets. Now research has extended into colored nets, which allows for the modification of the plants' physiological aspects and stimulation of certain light components.

A common misconception is that the nets are only used to control light intensity. The microclimate and water management are also impacted, however.

"Today our project focuses on colored nets and we are already moving on to the next step. It's not sufficient to just cover the orchard. You have to resolve certain questions like how to water and critical environmental aspects that determine quality potential under the nets," he explained.

"We're seeing how colored nets designed with differential light spectra allow you to modify physiological aspects."

Each color has its own function. Dr. Bastías is specifically working with red and pearl mesh.

"This particular light compostition influences specific plant processes and they are measured for photoreceptors that regulate aspects of agronomic interest, such as vegetative growth and coloring. In photosynthesis, all of this has an impact on potential plant production and obviously fruit quality," he said.

"We are committed to having better output, acheiving better plant growth control and improving fruit quality."

The Universidad de Concepción is developing an agreement with exporter Unifrutti, which has apple plantations in the O'Higgins, Maule and Bío Bío regions. The company works primarily with Gala, Fuji and Pink Lady varieties.

www.freshfruitportal.com