Watermelon Seedling Quality, Growth, and Development as Affected by Grafting and Chilling Exposure During Simulated Transportation

Grafted watermelon plants available in the United States are typically transported for a long distance from specialized nursery to production field. To investigate effects of chilling stress during transportation on early plant growth and development, grafted nongrafted ‘Tri-X-313’ seedless ( Citrullus lanatus ) seedlings were subjected low-temperature treatments applied over 72-hour period. The first experiment exposed 0, 6, 12, 24, or 48 hours 1 °C chilling, then moved 12 chamber remainder treatment second seven different combinations duration (0, 32, 41, 44, hours) create varied degree CDH at temperatures (between −0.4 1.2 °C). After 72 hours, transplanted pots filled with commercial substrate greenhouse evaluate floral development. Each had two repeats (spring summer) randomized complete block design (n = 10). Although greater exposure negatively affected visual quality photosynthetic capacity [measured by chlorophyll fluorescence parameter, variable fluorescence/maximum Fv/Fm )] both repeats, delay flowering after transplanting was significant spring only increased increasing (up 6 days exposure). Grafting found mitigate when same applied. When varied, damage leaves, decrease , delays female flower development best correlated base temperature 15 °C, 3 4 respectively. Our experiments further analyses literature data suggest that 50 70 [ BT °C] seems be critical threshold cause (3.5 1.3 plants). Therefore, if lower than expected seedlings, we mitigation measures taken so do not reach hours.