Relationship between rind hardness and rind tissue structure in watermelon

Abstract

This study was carried out to analyze the inheritance of watermelon rind hardness and the relationship between rind tissue structure and rind hardness for breeding crack resistant cultivars. For inheritance analysis, a crack-prone cultivar,'Beni Kodama', was hybridized with a crack resistant cultivar, 'Africa 22857' which was introduced from western Africa; their hybrid progenies were compared. 1. Hard rind cultivars and lines had thicker chlorenchyma cell layers and sclerenchyma cell layers, consisting of smaller, rounder compact cells in greater density than did the soft rind ones. We suppose that the rind tissue structure is correlated with the resistance to cracking following mechanical shocks. 2. Cell wall thickness is a relatively minor factor in rind hardness. 3. The rind hardness test of F1, F2 and BC1 progenies indicated that 'Africa 22857' has partially dominant genes for this characteristic. 4. Most characteristics associated with rind tissue structure are heritable because those in the F2 generation and back cross progenies are similar to that of 'Africa 22857'.