مطالعه ژنتيك تحمل به ريزش خورجين و صفات مرتبط در ژنوتيپ‌هاي كلزاي زمستانه با استفاده از روش تلاقي داي‌آلل

Study of Silique Shattering Tolerance Genetic and Related Traits in Winter Oilseed Rape Genotypes Using Diallel Cross Method

به منظور تجزيه ژنتيكي تحمل به ريزش خورجين در ژنوتيپ‌هاي كلزاي زمستانه، يازده ژنوتيپ ايراني و خارجي كلزا به‌صورت "داي آلل يك‌طرفه" با يكديگر تلاقي داده شدند. والدين به همراه نتاج F1 (جمعاً 66 تيمار) در قالب طرح بلوك‌هاي كامل تصادفي با سه تكرار در سال زراعي 97-1396 در مزرعه تحقيقاتي مؤسسه تحقيقات اصلاح و تهيه نهال و بذر كرج كشت و شاخص تحمل به ريزش خورجين و برخي از صفات مرتبط اندازه‌گيري شدند. تجزيه واريانس ژنوتيپ‌ها تنوع ژنتيكي بالايي را از لحاظ صفات مورد بررسي نشان داد. به همين ترتيب واريانس تركيب‌پذيري عمومي و خصوصي براي اكثر صفات ازجمله عملكرد دانه و همچنين شاخص تحمل به ريزش خورجين معني‌دار به‌دست‌آمد كه مبين سهم اثرات افزايشي و غالبيت ژني در كنترل ژنتيكي اين صفات بود. بنابراين به نظر مي‌رسد انتخاب دوره‌اي همراه با آزمون نتاج، روش اصلاحي مناسبي براي بهره‌گيري از هر دو جزء افزايشي و غيرافزايشي باشد. ميزان وراثت‌پذيري عمومي صفات بررسي‌شده در دامنه 87/93-81/78 درصد برآورد شد كه بيانگر سهم بالاي واريانس ژنتيكي در كنترل اين صفات بود. بررسي همبستگي صفات نشان داد كه همبستگي مثبت و معني‌داري بين صفت شاخص تحمل به ريزش خورجين با صفات عملكرد دانه (0/449=r) و ميزان روغن (0/313=r) وجود دارد. در مجموع والدين Zarfam و ES Artist با عملكرد مطلوب و شاخص تحمل به ريزش بالا به‌عنوان بهترين تركيب‌شونده‌هاي عمومي و دورگ‌هاي Okapi × Zarfam،Nafis × ES Artist ، Ahmadi × Nafis، Ahmadi × ES Neptune،Zarfam× ES Neptune ،Nafis × ES Natalie، وNima × ES Natalie به‌عنوان بهترين تركيب‌شونده‌هاي خصوصي براي برداشت مكانيزه كلزا و بهبود صفت تحمل به ريزش خورجين توصيه مي‌گردد.

Background and Objectives Although the opening of the silique is a valuable mechanism for the distribution of seeds in nature, it is also a significant problem in oilseed rape cultivation. Seed shedding from siliques at and after maturity is commonly referred to as pod shatter, and it reduces the grain yield of oilseed rape (Brassica napus). This factor, also called dehiscence, can cause losses of up to 50% of potential grain yield if harvesting is delayed and in adverse weather conditions. As a general consideration, canola is susceptible to shattering, and there is little genetic diversity associated with silique shattering tolerance in its commercial lines hence, increasing shatter tolerance is an important breeding objective. Materials and Methods In the present study, eleven parents were used to generate 55 hybrids. The experiment was carried out as a complete randomized block design with three replications at the seed and plant improvement institute. Silique Shattering Tolerance Index (SSTI) using Random Impact Test (RIT) and other related traits were measured during 2018. Griffing's model I of method II was used for the analysis of variance and the estimation of genetic parameters. Correlation coefficients for the studied traits and other calculations were performed using the SPSS software and Excel program. Results Analysis of variance of genotypes showed high genetic diversity for the studied traits. Similarly, the general and specific combining ability variances were significant for most traits such as grain yield and the silique shattering tolerance index. This indicates the contribution of additive and non-additive effects in the genetic control of these traits. The general heritability of the studied traits was observed in the range of 78.81% to 93.87%. Correlation coefficients of traits showed a positive and significant correlation between silique shattering tolerance index with grain yield and oil content. Moreover, Zarfam and ES Artist with a good performance and silique shattering tolerance index are considered the best general combiners. Okapi×Zarfam, Nafis×ES Artist, Ahmadi×Nafis, Ahmadi×ES Neptune, Zarfam×ES Neptune, Nafis×ES Natalie, and Nima×ES Natalie are recommended as the best specific combinations for mechanized oilseed rape harvest and improvement of the shattering tolerance trait. Discussion Low specific heritability of grain yield can be due to the more outstanding contribution of non-additive effects than additive effects. Various research studied variable estimation for general and specific combining ability and other parameters due to the difference in genetic materials and different weather conditions.