روش‌هاي آماري چند متغيره جهت مطالعه روابط بين صفات گلرنگ در شرايط آبياري معمولي و تنش خشكي

The Multivariate Statistical Methods to Study the Relationships among Safflower Traits under Normal Irrigation and Drought Stress Conditions

در مطالعات بيولوژيك از متغيرهاي آماري مي‌توان جهت آزمون تفاوت‌ها و شباهت‌ها و ارزيابي صفات مرفو-فيزيولوژيك در يك جمعيت گياهي استفاده نمود. به ‌منظور بررسي روابط بين اجزاء عملكرد دانه هشت ژنوتيپ گلرنگ (Carthamus tinctorius L) در شرايط آبياري معمولي و تنش خشكي و تعيين ژنوتيپ‌هاي با عملكرد بالا، آزمايشي به‌صورت كرت‌هاي يك‌بار خرد‌شده در قالب طرح بلوك‌هاي كامل تصادفي با سه تكرار در مزرعه دانشگاه قزوين در سال زراعي 1395 اجرا شد. رژيم آبياري در دو سطح آبياري معمولي و تنش خشكي در 50 درصد گلدهي در كرت‌هاي اصلي و هشت ژنوتيپ گلرنگ در كرت‌هاي فرعي در نظر گرفته شدند. نتايج نشان داد كه همبستگي صفات ارتفاع، تعداد شاخه فرعي، تعداد غوزه در بوته، قطر ساقه، كلروفيل، وزن گل، عملكرد زيستي و شاخص برداشت با عملكرد دانه در هر دو شرايط آبياري معمولي و تنش خشكي مثبـت و معنـي‌دار بود. براساس نتايج رگرسيون گام به گام و تجزيه مسير، شاخص برداشت و عملكرد زيستي در هر دو شرايط آبياري معمولي و تنش خشكي بيشترين اثر را بر عملكرد دانه داشتند. به دليل همبستگي بسيار بالا بين ميزان عملكرد با صفات شاخص برداشت و عملكرد زيستي در شرايط تنش، انتخاب ارقامي با شاخص برداشت و عملكرد زيستي بالا مي‌تواند در حصول حداكثر عملكرد در شرايط تنش بسيار مؤثر باشد. تجزيه به ‌عامل‌هانشان داد در هر دو شرايط آبياري معمولي و تنش خشكي 4 عامل حدود 82 درصد تغييرات را توجيه نمودند. اين عامل‌ها در شرايط آبياري معمولي به‌ ترتيب عملكرد دانه، وزن و تعداد دانه، اندازه غوزه، آب برگ و در شرايط تنش خشكي بنيه گياه، عملكرد دانه، وزن و تعداد دانه، اندازه غوزه و آب برگ ناميده شدند. بر اساس عامل عملكرد دانه و ترسيم باي‌پلات ارقام فرامان، محلي اصفهان، سينا و محلي كوسه در هر دو شرايط آبياري معمولي و تنش خشكي عملكرد بالايي را ارائه نمودند.

Background and Objectives Drought stress is one of the most substantial environmental stresses affecting agricultural productivity around the world and may result in considerable yield reduction. The human population is expected to increase to over 8 billion by the year 2020. Therefore, providing adequate food and preventing crop yield reduction is essential. Plant breeding can solve this problem to some extent. Evaluating yield components and their inter-relationships as well as detecting suitable selection indices are very important in the safflower breeding program. The multivariate statistical analysis can provide more insights into the deep structure of data and traits’ relationships Materials and Methods In order to study the relationships between yield components of eight genotypes of safflowerunder normal irrigationand drought stress conditions and determine the high yield genotypes, a split-plot experiment was conducted in a randomized complete block design with three replications in the research field of Imam Khomeini International University, Qazvin. Irrigation regime included normal irrigation(irrigation after 60 mm evaporation from class A pan evaporation) and drought stress (watering until 50% flowering similar to normal irrigationand 50% flowering to maturity and irrigation after 100 mm evaporation from class A pan evaporation) were considered as main plots. Eight genotypes, including Kuseh Local, Sina, Isfahan Local, Mexican 88, Faraman, Soffeh, Goldasht, and Mexican 11 were used too. Results The analysis of the variance showed that the irrigation effect was significant for traits 1000 grain weight, flower weight, harvest index, and grain yield. There were significant differences among the genotypes for most of the measured traits, except boll diameter, boll number per plant, relative water content, and relative water loss. Plant height, shoot number, boll number, stem diameter, chlorophyll value, flower weight, biological yield, and harvest index positively correlated with the grain yield in both normal irrigation and drought stress conditions. Based on the results of stepwise regression and path analysis, biological yield and harvest index in both normal irrigation and drought stress conditions had the greatest effect on grain yield. Due to the high correlation between yield and harvest index and biological yield under stress conditions, the selection of varieties with high harvest index and biological yield can be very effective in achieving maximum yield under stress conditions. Factor analysis revealed that 4 factors accounted for approximately 82% variance changes in both normal irrigation and drought stress conditions. These factors were called yield, seed, boll size, and leaf water, respectively under normal irrigation, andplant vigor, yield, seed, boll size, and leaf water, respectively under drought stress conditions. Based on the seed yield factor and the biplot display, Faraman, Mahali Isfahan, Sina, and Mahali Kuseh were determined as high yield genotypes both in normal and drought stress conditions. Discussion Grain yield is a quantitative trait with a low broad sense heritability. Therefore, identifying the traits correlated with grain yield is a suitable strategy for the improvement and the indirect selection of grain yield. Stepwise regression and path analysis are efficient and useful statistical approaches for reaching the above aim. According to the results, the traits of the harvest index and biomass were recognized as the best suitable traits for indirect grain yield selection under normal and drought stress conditions.