Utilize Longan Diversity for Variety Improvement

 

Indonesia Longan | ICSFRI

Baiq Dina Mariana 
Indonesian Citrus And Subtropical Fruits Research Institute

Since the trend of low land longan at the beginning of the 2000s, many longan varieties have been introduced to Indonesia. First-generation of varieties introduced included Pingpong, Diamond River and Itoh and the last one introduced just few years back is Ruby which looks attractive due to its red fruit peel. However, of those varieties introduced, only a few have been developed in a various scale of plantation or cultivation area, namely Itoh and Kateki. These varieties have high quality of fruits characterized by appropriate fruit size, sweet taste, crunchy and thick flesh accompanied by small to medium seed size.

The number of longan varieties with their respective uniqueness and advantages actually provide an opportunity for breeding of new varieties. By mapping the advantages of each variety, farmers/growers or breeders could create their own varieties based on the idiotype preferred. The table below shows the characters of varieties which are commonly known to the public, including varieties that have not been released officially but already developed in the community, which can be used as a reference in selecting varieties to be used as a parent in the breeding program.

Tabel 1. Indonesia pingpong variety

Based on the table above, a scheme of breeding using simple hybridization then can be made. Common rule is that varieties that will be improved is used as a female parent. Reciprocal crossing could also be done for further enhance the diversity and also improve the chances of getting the desired varieties. The following table presents a selection of crossing schemes for obtaining varieties with certain characters.

Tabel 2. Pingpong crossing schemes for obtaining varieties with certain characters.

This simple crosses could be done by anyone without complicated techniques and tools. However, before hybridization one needs to know the flowering type since longan has at least two types of flower needed for successful hybridization. Male flower has a round but flatten top while the female one has a round shape but tapered top (see red circle in Figure 1).

Figure 1. Male (left) and female (right) longan flowers

              Tools needed are a pair of plant scissors, tweezers, and paper bag (can be made from (oil paper). Crosses should be done when the sunshine felt warm (after 8 o’clock in the morning) to stimulate the opening of flower. Female flowers are selected in the balloon phase (already expanding but not yet blooming). Anther from female flower must be disposed first. Flowers are crossed by putting the pollen from anther onto stigma. Longan flowers fall easily therefore crossing should be done carefully.  After crossing, flowers are covered with paper bags and given a label containing the date, and unique code representing the female and male parents. The cover can be opened a week after crossing. If the crossing is successful, the flowers will stick to the panicle, or fall otherwise.

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