Combining ability and heterosis for root structure and graft-related traits of interspecific Cucurbita rootstocks

Abstract

Interspeci c hybrid Cucurbita rootstocks (Cucurbita maxima × Cucurbita moschata) are the most widely used rootstocks for Cucurbitaceous vegetables in the world. In recent years, scientists have focused on understanding and exploiting root architectures as new opportunities for crop improvement. Selection of parents and hybrids based on combining ability test is an effective approach in interspeci c hybrid variety breeding. However, very little information is available on the combining ability tests for the rooting and graft-related traits in these rootstocks. Ondokuz Mayis University and Black Sea Agricultural Research Institute are conducting a program to breed Cucurbita rootstocks of Turkey for fteen years. In this study, seven C. maxima (BC 5 F 1 generation) lines as female parents and three C. moschata (S 6 generation) lines as male parents were used to obtain 21 crosses. Interspeci c hybrids and their parent rootstocks grafted onto watermelon were analyzed in terms of general combining ability (GCA), speci c combining ability (SCA), heritability, and heterosis for roots and graft-related traits including root volume (cm 3 ), root length (m), root dry weight (g), hairy root rate (%), average root diameter (mm), shoot dry weight (g), graft success rate (%), and hypocotyl thickness ratio (%) by using line × tester mating design. The quotient of GCA/SCA effects for all root and hypocotyl traits were higher than 1, suggesting the preponderance of additive over non-additive gene action in the expression of these traits, whereas graft success was controlled by additive and non-additive gene effects. It was determined that average root diameter had high heritability (63.85%) and the other traits had intermediate heritability ranging from 40.59% to 58.98%. Combining ability analyses indicated that FTS5, GH12, and GRD17 lines were promising parents with greater general combining ability. Three crosses, GRD17 × FTS5, B12 × FTS5, and BH5 × CHI2 showed superior mid-parent heterosis and signi cant SCA for most characters. Present ndings will provide signi cant contributions in understanding of inheritance and then achieving desirable improved rootstocks in C. maxima × C. moschata.

The selection of intra-inter specific Cucurbita rootstocks for grafted melon seedlings

“…1). were made according to the Karaağaç (2021). Cultural practices (irrigation, fertilization, etc.)…”

“…It has also been reported to be grafted onto luffa. (King et al, 2010;Balkaya, 2014;Karaağaç, 2021). Interspecific hybrid squash rootstocks, particularly those derived from a cross between C. maxima and C. moschata, have been extensively used in melon grafting in order to enhance their growth and yield.…”

“…As a result, this condition not only leads to increased yield but also aids in disease control (Lee, 1994;Balkaya, 2014;Karaağaç et al, 2018;Karaağaç, 2020). In recent years, researchers have directed their attention towards examining root system architectures as promising avenues for crop improvement (Sarıbaş et al, 2019;Karaağaç et al, 2020;Karaağaç, 2021). In rootstock breeding programs, one of the most challenging tasks is the specification of phenotypic variability in root characteristics.…”

“…By examining RSA, researchers can gain insights into the spatial and structural arrangement of roots, which plays a crucial role in determining how plants interact with their environment (Ye et al, 2018). Therefore, the examination of root system architecture (RSA) through selected lines holds great potential and utility (Sheshshayee et al, 2011;Saribaş et al, 2019;Karaağaç, 2021).…”

Estimation of Gene Effect and Combining Ability for Yield and Yield Components Using Line x Tester Analysis in Rice (Oryza sativa)

“…In plant breeding, general combining ability (GCA) and specific combining ability (SCA) are used to measure the effects of additive and non-additive genes on the inheritance of traits (Fasahat et al 2016). GCA is attributed to additive gene effects, while SCA is attributable to non-additive gene action, which may be due to dominance (Abera Muluneh et al 2020;Karaağaç 2021). Heterosis, also known as hybrid vigor, is the phenomenon in which the offspring of two genetically different parents exhibit superior traits compared to their parents.…”