Pumpkin (Cucurbita moschata) has been increasingly used as bloomless rootstock for cucumber (Cucumis sativus), but it is sensitive to low-temperature, which is the major bottleneck for winter cultivation. Hence, to develop low-temperature tolerant rootstock varieties, it is needed to identify tolerant germplasm from a wide range of genetic resources. For this, we developed a selection criterion for a quick assessment of low-temperature tolerance in pumpkin germplasms from different geographical origins. We considered various indexes for the fast evaluation of low-temperature tolerance, including seedling developmental stage, type of seedling (excised or non-excised), growth space, etc. Under the testing condition (17℃/7℃, 8 hours light/16 hours dark, 150 μmol m^-2s^-1 light intensity), we found a correlation (r=0.71*) in root growth between 3 weeks-cultured excised seedlings and 6 weeks-cultured non-excised seedlings. Therefore, we extrapolate that excised cotyledonary stage seedling treated for 3 weeks is sufficient to differentiate the tolerant germplasms. Using this screening method, we identified the “S81015” could prevail low-temperature stress. Further, we tested grafting compatibility and growth of grafted cucumbers under the low-temperature condition to assess the effect of rootstock and identify low-temperature tolerant and grafting-compatible rootstock germplasm. Upon grafting, we found a high correlation (r=0.97**) between the root fresh weight of 6 weeks-cultured non-excised seedlings and the shoot fresh weight of the grafted cucumbers. In summary, we could identify the low-temperature tolerant pumpkin germplasms by screening at the early developmental stage. Further, as a rootstock, the tolerant pumpkins also fortified the low-temperature tolerance of grafted cucumbers.

Citations

Citations to this article as recorded by  

• Identification of a Novel Candidate Gene for Chilling Tolerance in Pumpkin (Cucurbita moschata) Using Whole-Genome Resequencing
  Hemasundar Alavilli, Jeong-Jin Lee, Chae-Rin You, Sang-Choon Lee, Kihwan Song
  Journal of Plant Biology.2023; 66(4): 317.     CrossRef