A comparison of flooding tolerance of guava tree propagated from shoot layering and seedling

Guava orchards in Nakhon Prathom province, Thailand were damaged by severe flooding in 2011 resulting in the death of guava trees. Guava trees were susceptible to flooding conditions because most of them were usually propagated by shoot layering or shoot cutting. Using seedlings or suitable rootstocks could increase the flooding tolerance to the guava trees. However, there is no information about using guava seedling as a rootstock for flooding tolerance. The objectives of this study were to study and compare potential response parameters of flooding tolerance between guava trees cultivated from shoot layering and seedling. A 2x2 factorial experiment with two forms of propagation of 'Wan Pirun' guava trees combined with two levels of flooding treatment including submerged in water tanks (water level 10 cm above soil level) and no submerging for 8 weeks was done. The results showed that propagation method and flooding treatments had effect on shoot and root growth. Guava trees propagated by shoot layering showed the highest values of leaf, shoot, and root weights under non-submerged condition. Both seedling and shoot layering trees under flooding conditions showed the lowest value and presented leaf chlorosis and leaf falling. Bark cracking and adventitious root formation were found only in guava trees from seedlings after 5 weeks of flooding. However, guava seedling trees had a lower percentage of reduction in all parameters than the trees from shoot layering under flooding condition. In addition, a wilting score of the seedling trees was lower under flooding conditions. Leaf greenness of both seedling trees and shoot layering trees was not significantly different. Thus, the guava trees cultivated from seedlings were more tolerant than those from shoot layering under flooding conditions.