Professor, Department of Genetics and Plant Breeding, Faculty of Agricultural Sciences, University of Agricultural Sciences and Natural Resources, Sari, Iran
Abstract: (393 Views)
Extended Abstract
Background: Canola (Brassica napus L.) has become the third most valuable edible oilseed crop worldwide after soybean and oil palm. Considering the importance of canola cultivation, it is important to identify genotypes with high yield potential to obtain superior crosses. Combining ability can determine the capacity of an individual toward the transmission of superior performance to offspring. Diallele analysis is used as a very powerful and efficient method to estimate genetic parameters, gene function, specific and general combinability, and determine the amount of heterosis. In this study, therefore, diallele crossing was used in eight spring and winter cultivars to estimate the combinability and heterosis of these cultivars in terms of phenological and morphological traits to identify promising parents and hybrids for future breeding programs.
Methods: Four spring canola cultivars (RGS, Asa, Baharan, and Dalgan) and four winter cultivars (Zarfam, Nima, SLM2246, and Okapi) were crossed as a one-way diallele design in 2022-2023. The hybrids of the first generation, along with eight parents (36 genotypes in total), were evaluated in a randomized complete block design with three replications in 2023-2024. The studied traits included the number of days to flowering, the number of days to maturity, plant height, length of the main branch, the number of sub-branches, the number of pods in the main branch, the number of pods in the sub-branch, pod length, the number of grains per pod, 1000-grain weight, and seed yield. Statistical calculations of the measured data were performed using DIALL (1.1) and SPSS (16) software.
Results: The results of diallele analysis in both general combinability (GCA) and specific combinability (SCA) were significantly different among the parents and hybrids for all the investigated traits; therefore, additive and non-additive components play a role in the inheritance of all traits. On the other hand, the estimates of GCA variances were higher than the SCA variance in all the studied traits, indicating that additive variance was more than the non-additive variance. Spring genotypes with negative and significant GCA for the number of days to flowering will be prioritized to reach early cultivars. Negative and significant results of SCA were observed in six crossings for this trait. Most crosses with negative and significant SCA had at least one parent with negative and significant GCA for this trait. In terms of plant height, RGS and Dalgan genotypes showed significant negative GCA. Six hybrids had negative and significant SCA for plant height; hence, they can be used to reduce height in breeding programs. There was a positive and significant GCA in increasing the number of pods in the main branch of the Baharan, Dalgan, and Asa genotypes and the number of pods in the sub-branch of the Nima, SLM046, and Okapi genotypes. Therefore, these genotypes will be prioritized to increase these traits. In addition, positive and negative SCA were observed in crosses for these traits. Asa, Baharan, and Zarfam genotypes with positive and significant GCA were recognized as the best combiners to increase the number of seeds in the pod. Seven hybrid compounds with positive and significant SCA were recognized as superior compounds for increasing this trait. Asa and Dalgan genotypes with significant positive GCA were considered among the desirable genotypes for increasing grain yield. SCA was observed positively and significantly in 11 crosses, which indicated the non-additive effect of genes to increase this trait. The degree of heterosis compared to the superior parent for the number of days to flowering trait in most of the crosses was significant in the negative direction. Varieties RGS×Okapi, Baharan × Okapi, and Asa × Okapi crosses with significant heterosis will be given priority in terms of early maturity. Considering the desirability of shortening in rapeseed, RGS × Asa and RGS × Zarfam crosses with significant negative heterosis are preferred for height reduction. The crosses SLM046 × Okapi and Asa × Zarfam showed the highest amount of heterosis in the number of pods in the main branch. The crosses Nima × Okapi, SLM046 × Okapi, and Baharan × Dalgan with the highest amount of heterosis will be prioritized to improve the number of pods in the branch. RGS × Okapi, Baharan × Dalgan, Asa × Okapi, and RGS × Zarfam crosses showed significant positive heterosis in terms of the number of seeds in the pod. In terms of grain yield, Dalgan × Okapi, Dalgan × SLM046, Zarfam × SLM046, Baharan × Zarfam, and Nima × Okapi crosses are preferred with the highest amount of heterosis.
Conclusion: The estimation of traits' combinability showed that RGS and Dalgan cultivars were the best general combiners to reduce the number of days to flowering, the number of days to maturity, and plant height. Therefore, these cultivars can be considered a source of desirable alleles to achieve early maturity. In addition, Asa and Baharan cultivars were recognized as the best combiners to increase yield and some related traits. Nima × Okapi, Dalgan × Okapi, RGS × Dalgan, and Asa × Okapi crosses were the best specific combiner hybrids for increasing yield and some related traits, while these crosses showed positive and high heterosis in seed yield. Therefore, their parents can be suggested for the production programs of new cultivars and improvement of canola genotypes for seed yield.
Background: Canola (Brassica napus L.) has become the third most valuable edible oilseed crop worldwide after soybean and oil palm. Considering the importance of canola cultivation, it is important to identify genotypes with high yield potential to obtain superior crosses. Combining ability can determine the capacity of an individual toward the transmission of superior performance to offspring. Diallele analysis is used as a very powerful and efficient method to estimate genetic parameters, gene function, specific and general combinability, and determine the amount of heterosis. In this study, therefore, diallele crossing was used in eight spring and winter cultivars to estimate the combinability and heterosis of these cultivars in terms of phenological and morphological traits to identify promising parents and hybrids for future breeding programs.
Methods: Four spring canola cultivars (RGS, Asa, Baharan, and Dalgan) and four winter cultivars (Zarfam, Nima, SLM2246, and Okapi) were crossed as a one-way diallele design in 2022-2023. The hybrids of the first generation, along with eight parents (36 genotypes in total), were evaluated in a randomized complete block design with three replications in 2023-2024. The studied traits included the number of days to flowering, the number of days to maturity, plant height, length of the main branch, the number of sub-branches, the number of pods in the main branch, the number of pods in the sub-branch, pod length, the number of grains per pod, 1000-grain weight, and seed yield. Statistical calculations of the measured data were performed using DIALL (1.1) and SPSS (16) software.
Results: The results of diallele analysis in both general combinability (GCA) and specific combinability (SCA) were significantly different among the parents and hybrids for all the investigated traits; therefore, additive and non-additive components play a role in the inheritance of all traits. On the other hand, the estimates of GCA variances were higher than the SCA variance in all the studied traits, indicating that additive variance was more than the non-additive variance. Spring genotypes with negative and significant GCA for the number of days to flowering will be prioritized to reach early cultivars. Negative and significant results of SCA were observed in six crossings for this trait. Most crosses with negative and significant SCA had at least one parent with negative and significant GCA for this trait. In terms of plant height, RGS and Dalgan genotypes showed significant negative GCA. Six hybrids had negative and significant SCA for plant height; hence, they can be used to reduce height in breeding programs. There was a positive and significant GCA in increasing the number of pods in the main branch of the Baharan, Dalgan, and Asa genotypes and the number of pods in the sub-branch of the Nima, SLM046, and Okapi genotypes. Therefore, these genotypes will be prioritized to increase these traits. In addition, positive and negative SCA were observed in crosses for these traits. Asa, Baharan, and Zarfam genotypes with positive and significant GCA were recognized as the best combiners to increase the number of seeds in the pod. Seven hybrid compounds with positive and significant SCA were recognized as superior compounds for increasing this trait. Asa and Dalgan genotypes with significant positive GCA were considered among the desirable genotypes for increasing grain yield. SCA was observed positively and significantly in 11 crosses, which indicated the non-additive effect of genes to increase this trait. The degree of heterosis compared to the superior parent for the number of days to flowering trait in most of the crosses was significant in the negative direction. Varieties RGS×Okapi, Baharan × Okapi, and Asa × Okapi crosses with significant heterosis will be given priority in terms of early maturity. Considering the desirability of shortening in rapeseed, RGS × Asa and RGS × Zarfam crosses with significant negative heterosis are preferred for height reduction. The crosses SLM046 × Okapi and Asa × Zarfam showed the highest amount of heterosis in the number of pods in the main branch. The crosses Nima × Okapi, SLM046 × Okapi, and Baharan × Dalgan with the highest amount of heterosis will be prioritized to improve the number of pods in the branch. RGS × Okapi, Baharan × Dalgan, Asa × Okapi, and RGS × Zarfam crosses showed significant positive heterosis in terms of the number of seeds in the pod. In terms of grain yield, Dalgan × Okapi, Dalgan × SLM046, Zarfam × SLM046, Baharan × Zarfam, and Nima × Okapi crosses are preferred with the highest amount of heterosis.
Conclusion: The estimation of traits' combinability showed that RGS and Dalgan cultivars were the best general combiners to reduce the number of days to flowering, the number of days to maturity, and plant height. Therefore, these cultivars can be considered a source of desirable alleles to achieve early maturity. In addition, Asa and Baharan cultivars were recognized as the best combiners to increase yield and some related traits. Nima × Okapi, Dalgan × Okapi, RGS × Dalgan, and Asa × Okapi crosses were the best specific combiner hybrids for increasing yield and some related traits, while these crosses showed positive and high heterosis in seed yield. Therefore, their parents can be suggested for the production programs of new cultivars and improvement of canola genotypes for seed yield.
Type of Study: Applicable |
Subject:
اصلاح نباتات، بیومتری
Received: 2024/12/21 | Accepted: 2025/01/26
Received: 2024/12/21 | Accepted: 2025/01/26
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