Morphological and anatomical characterization of colchicine induced polyploids in watermelon

Abstract This study aimed to elucidate the effective colchicine concentration induced polyploidization distinction based on morphological and anatomical features in watermelon. Watermelon seeds were soaked in different colchicine concentrations (0.05, 0.1, 0.5%) for several durations (24, 48, 72h) to induce polyploidization. Putative polyploids were evaluated regarding the morphological and anatomical traits compared to the diploid one (control). Colchicine @ 0.5% for 72h revealed the lowest germination percentage with high mortality in putative polyploids compared to diploids. Morphological traits revealed in vigorous growth in putative tetraploids with slower germination speed whereas the putative octoploid exerted suppressed growth compared to tetraploids and diploids. Besides, in respect of the reproductive biology, the petal number (6), pollen size and viability were remarkably higher in induced polyploids that confirmed the successful tetraploid induction by 0.5% colchicine treatment in seed for 72h. Similarly, the bigger stomatal size with lower density was also noticed in induced tetraploids compared to the diploid one using the same treatment after anatomical analyses. Meanwhile, PCA and correlation matrix illustrated that among the 20 variables polyploid induction efficiency% (PIE), leaf length (LL), guard cells distance (GCD), pollen viability% (PV) were recognized as the most effective morphological and anatomical indicators for successful polyploid induction confirmation with colchicine in watermelon. The present findings would be the basis for distinguishing colchicine induced polyploids as improved genetic resources to enhance the seedless triploid breeding in watermelon.