Indices for varietal identification of mango (Mangifera indica L.)

The lack of a standard procedure for identifying mango varieties at the seedling stage has been a major problem faced by the Philippine mango industry. To address this problem, we developed procedures to identify the variety of mango seedlings, with emphasis on the Carabao mango variety, using objective and easy-to-use accurate indices or markers, involving physical characteristics of mango seedlings and chemical reactions of the mango leaf extract. Results showed that the Carabao variety had light green with light brown tinge and horizontal flushes while Pahutan variety had light green but downward flushes at one week after flushing. Pico mango had light brown to light violet flushes, while Katchamitha (Indian variety) had light to darker violet flushes. Their colors would become more intense but would eventually all turn to green after 3 or 4 wk. The shapes of Carabao, Pahutan and Pico leaves were observed to be narrowly trullate, while the Katchamitha leaves were narrowly rhombic. Leaf tip shape was observed to be narrowly accuminate for the Katchamitha, Pahutan and Pico varieties and abrupt accuminate leaf tip only for the Carabao variety. Differences in the leaf aroma were also observed and supported by the profiles of leaf volatiles using Gas Chromatography.-Mass Spectrometry (GC-MS). The leaf total phenolic extract of Pahutan had the most intense green color followed by Carabao, Pico and Katchamitha which showed a similar yellowish green color. These extracts, when reacted with acidified vanillin treated paper, gave light pink color for the Carabao variety, pink color for the Pico and Katchamitha varieties and light green color for Pahutan. Results indicate that the most practical method for identifying mango varieties especially for large numbers of seedlings is through the color and orientation of young leaves or flushes. This technique can also be applied in identifying mature mango trees.