Document Type : Research Paper - Plant Breeding
Authors
1 Seed and Plant Improvement Research Department, Safiabad Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Dezful, Iran
2 Professor., Seed and Plant Improvement Department, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
Abstract
Wheat (Triticum spp.) is one of the most important staple foods for the human diet worldwide. In 2022, wheat has been cultivated in 219.2 million ha worldwide with a total production of over 808.4 million tons. This makes it the third most important crop in terms of global production. Wheat is cultivated across a wide range of latitudes, from 67° North to 45° South including highly diverse environmental conditions. Wheat is a staple commodity for human feeding including Iranian society and that is why it located as the first priority in Iran’s agricultural development program. Self-sufficiency on wheat production in a few last decades has become a national goal in Iran and resulted successful outcomes. Breeders should determine biotic and abiotic stresses in target environment and minimize their negative effects on yield using different breeding approaches. Temperature is an important environmental factor that its irregular variation consequently effect on terminal yield. Heading date is still an important phonologic criterion in wheat breeding and genotypes comparison.
Materials and methods
Average of minimum and maximum temperature in two periods, from sowing to heading as well as Heading to physiological maturity, in six growing season from 2012-2013 to 2017-2018 were recorded and calculated to evaluate their effect on grain yield. In this study, the data of 14 international treasury and 12 national experiments of the warm southern climate (a total of 1226 genotypes) have been used between the crop years 1391-92 to 1396-97.. two stages before and after the appearance of the spike and The influence of thermal factors in each stage and their relationship with grain yield have been investigated. Considering that the date of physiological treatment was recorded for the first repetition, the data related to the first repetition of each vault and experiment were used in the evaluation phase after the appearance of the spike to calculate the correlation coefficients. The META-R software, which was designed in 2015 at the International Maize and Wheat Breeding Center (CIMMYT), was used to analyze the variance and calculate the genotypic and phenotypic correlation coefficients of the data of each experiment.
Results and Discussion
Thermal amplitude (T Max- T Min) is an environmental index to evaluate thermal effect on phonologic stages, growth and development and yield. Variation in minimum and maximum average of temperature from sowing to heading were 7.61 -18.96 0C in earliest and 7.62-21.46 0C in latest genotypes, respectively. From heading to Physiological maturity minimum and maximum average were between 11.1-15.74 and 24.51-31.39 0C, respectively. The correlation coefficients between grain filling period and thermal factors did not follow a stable trend. Correlation between yield and days to heading, average of minimum and maximum of temperature from sowing to heading period were not constantly significant, while significant correlation between yield and thermal amplitude in pre-heading stage was detected. Moreover, not stable correlation were found between yield and other variables in reproductive phase. In this study, the relationship between the yield and the length of the spike emergence period to the physiological maturity did not follow a constant and stable trend. Therefore, it is suggested to evaluate in a separate study the relationship between yield, grain filling speed and grain filling period with environmental factors and other biotic and abiotic stresses.
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