The promise of multiple rootstock technology

The root system is the basic foundation of plants. The roots function as anchorage and the lateral roots with root hairs absorb water and nutrients as well as, oxygen for respiration. Multiple rootstocks or multi-root system is the growing of plants with two or more rootstocks as shown in the accompanying picture. Fruit-exporting counties – Taiwan, Thailand and Australia – are practicing this technique.

This superior technology has so many advantages over the usual single rootstock system.Growth and development are accelerated making the tree more prolific as it overcomes the biennial (alternate) fruiting habit. Production can be enhanced by 300 percent.

Fruit trees like mango produces heavy fruiting only after every year and if forced to bear fruits by applying KNO3, the tree will have a short life span as what happened in Cebu, Zambales, Nueva Ecija and Pangasinan.

Better root anchorage enables the trees to resist strong winds and other adverse conditions. Moreover, more root system essential in taking in nutrients from fertilizers minimize fertilizer losses to evaporation and leaching.

Gestation period (fruiting) of the young trees is shortened by one half of the normal waiting time. Physiological maturity is also enhanced. A five-year old triple rootstocked tree is comparable to an 8 to 10 year old fruit-bearing tree. As the tree will bear fruit early, producing off-season quality fruits will command higher prices. The tree becomes non-seasonal due to its reinforced nature.

Faster propagation or reproduction of desired variety with lesser mortality, more uniform growth and longer life span can be achieved, thereby, enhancing and prolonging productivity.

Imported varieties of seedlings like jackfruits and guapples will become resistant to phythopthora when double rootstocked with a native variety. It has been observed that latexless jackfruits and guapples and other imported varieties grown from seeds died of phytophtora after 4-6 years.

Pioneers And Propagators

In the Philippines, Engr. Telesforo L. Umali and his late brother National Scientist Dean Dioscoro L. Umali introduced double and triple stocked from Thailand, Taiwan and other fruit producing countries during the early 80’s. Engr. Umali’s triple rootstocked rambutan fruits as early as May and June where traditionally planted rambutan has only begun to flower .

Among the propagators of the technology is Bernardo Dizon who maintain a fruit tree plantation at the Ninoy Aquino Parks and Wildlife Nature Center at North Avenue, Diliman, Quezon City. Here he offers free seminars on fruit tree propagation in cooperation with Protected Areas and Wildlife Bureau (PAWB) of the Department of Environment and Natural Resources (DENR). The schedule of the seminars is Saturday, Sunday and Monday at the DENR-PAWB-Dizon Fruit Botanic Garden and Learning Center.

There are other practitioners of the multiple rootstock.

According to Mr. Rush of Clark Airbase in Pampanga, his father, a professor at the University of Michigan, USA had used the multiple rootstock system in his plantation of oranges and apples since the early 60’s. A Taiwanese friend of Mr. Ramon Cua introduced multiple rootstocking of calamansi and passion fruit in Cavite in the early 80’s.

Educational institutions also propagate multiple rootstocking technology. The Cavite State University in Indang, Cavite successfully showcased exotic fruit trees such as lychee, durian, rambutan, lanzones and many more. These trees are now producing fruits in commercial quantity.

Twenty five hectares of double and triple rootstocked mangoes are being maintained by the Ramon Magsaysay Technological University in San Marcelino, Zambales. Results show that the multiple rootstocked mangoes grows fast with well developed crown. Dizon also has 10-hectare double rootstocked Guimaras mango plantation at a nearby site. The mangoes grow well and after two years begun bearing fruits.

At CLSU-Dizon Fruit Research and Techno-Demo Center at the Central Luzon State University in Munoz, Nueva Ecija multiple rootstocked lychee, durian, rambutan, lanzones Magallanes Davao pomelo, oranges, Guimaras carabao and imported mangoes, as well as, other exotic fruit trees are thriving and fruiting well. In the farm of the late Jose Burgos, the 6-year old multiple rootstocked carabao mango and the 12-year old single rootstock now have the same size and crown.

It has been observed that triple rootstock mangoes and durian when applied with the right amount of fertilizer and proper irrigation will flower abundantly without smudging.

Procedure

All planted seedlings must be of the same size to avoid development of a dominant rootstock.

In case a rootstock is slightly bigger than the other two seedlings it must be placed on the lower portion while the smaller or slender ones should be at the uppermost part of the point of union.

Rootstocks must be as close as possible to form a vertically straight single trunk (see picture of lanzones).

The slice of the grafted seedlings must be one-third of the stem size, which should have a minimum length of one and one half to two inches. The slice of the rootstock must be longer by one half inch to one inch and the slice below must be of the same level with the grafted seedlings.

All wounds of the grafted seedlings must be attached with the corresponding wound of the rootstocks for proper fusion. It should be wrapped properly with an ordinary plastic straw. There must always be excess wound on the rootstock that shall produce callous impression to determine if the rootstock can be cut after two months.

Place a bionic straw tie at the rootstock above the bridge-graft or point of union to avoid cutting the scion or cultivar.

The top portion of the rootstock must be cut after two to three months from fusion. Allowing the rootstock’s top to grow along with the scion will stunt the growth and may even lead to the death of the variety.

Place the stake beside and tie the seedlings for training as one plant to avoid breaking during strong winds.

From three to four months from the date of multiple rootstocking, remove the straw to prevent choking or breaking the stem.

Always place the tie below the point of union to prevent splitting during the first six months.

Never allow the shoots to grow below the point of union.

With cloning and multiple rootstock technology and different weather condition in the country, it is now possible to have a year-round abundant supply of fruits for local consumption and exports that will make a substantial contribution to the GDP (gross domestic products).