Response to Modified Mass Selection in White and Orange Fruit Skin Ornamental Pumpkin (<I>Cucurbita pepo</I> L.) Populations

Abstract

Two populations of white and orange skin ornamental pumpkins (Cucurbita pepo L.) were collected from a farmer’s field in Northern Thailand and then subjected to modified mass selection in three cycles, with the objective of increasing the number of fruits per plant and frequency of skin color in both populations. Progenies seed of base population (M₀) and three improved populations (M₁, M₂ and M₃) were evaluatedin separated experiments at the Agricultural Innovation Research, Integration, Demonstration, and Training Center, Faculty of Agriculture, Chiang Mai University, from November 2020 to January 2021. The experimental design followed a randomized complete block design. The results revealed that after undergoing three selection cycles (M₃), the white and orange fruit skin populations showed an increase in the number of fruits per plant compared to the initial population (M₀). The white fruit population exhibited an increase of 1.7 fruits per plant per selection cycle, resulting in a response rate of 88.6%. Similarly, the orange fruit population demonstrated an increase of 1.7 fruits per plant per selection cycle, with a response rate of 97.9%. Furthermore, the frequency of white fruit skin in the third selected cycle of the white fruit population increased by 33.3%, while the frequency of orange fruit skin in the selected orange fruit population increased by 27.0%. The two populations showed the similar trends of the correlation coefficient. This study highlights that mass selection can effectively enhance the number of fruit per plant and the frequency of white and orange fruit skin in ornamental pumpkin populations. The improved populations can serve as valuable genetic resources for future breeding endeavors.