Abstract
THIS STudy was aimed to induce genetic variation toward drought tolerance after treatment with EMS as a mutagen to two maize inbred lines and their single hybrid. The experiment was carried out at Abo-Ghraib Research Station, Baghdad during the spring season of 2019. The experiment included three irrigation intervals 7, 9 and 11, four concentrations of EMS (0, 50, 60, and 70 mM) and three maize genotypes distributed in three replications using randomized complete block design (RCBD) with split-split plot arrangement which included three irrigation intervals 7, 9 and 11 days occupied the main plot, while the sub plots included three maize genotypes, and four EMS concentrations which were distributed in sub-sub plots. Results were revealed significant differences among EMS treatments and irrigation interval treatments. The inbred line 5 in control treatment showed a significant increase in days for both anthesis and silking (70.11 and 71.94) days, respectively. Plants of Nahrain hybrid also showed a super performance in plant height, leaf area, and number of rows ear-1, with a mean of 154.47cm, 746.31cm2 and 17.83 row ear-1, respectively. The irrigation intervals of 9 and 11 days were significantly decreased the mean performance of genotypes, compared to the shortest irrigation interval (7 days) which had highest mean in most traits. None treated plants (0 mM EMS) had a significant effect on the performance of most studied traits, except the anthesis and silking time, which gave the highest values under the concentration 60 mM with 69.11 and 70.48 days, respectively. Hybrid plants interacted significantly with the EMS concentration of 0 mM producing the maximal means of plant height and leaf area (169.56cm and 759.78cm2 respectively). On the other hand, the hybrid was significantly interacted with the shortest irrigation interval in the mean traits of plant's height and leaf area (163.50 cm and 757 cm2, respectively). The triple interaction between hybrids, shortest irrigation interval and EMS concentration of 60 mM had significantly increased leaf area reached 769.67cm2, meanwhile the triple interaction between hybrid plants, shortest irrigation interval, and the EMS concentration of 0 mM recorded the highest value of plant yield (199.67g). It can be concluded from the current study that the genotypes differed in their response to 9 and 11 days irrigation intervals, with a negative effect of the later interval on the vegetative and yield traits of maize compared with shorter irrigation interval.
Highlights
Agricultural activities depleted more than 70% of the global consumed water, and these requirements are increasing by 90% in the developing countries with a permanent water shortages [5]
ethyl methanesulphonate (EMS) is one of the most common chemical mutagens used for inducing genetic variation without causing large-scale chromosomal aberrations in which the progeny survival rate may decrease [22]
The the highest value was obtained at genotypes required 72.86 days to anthesis the concentration 70 mM EMS accompanied under the longer irrigation interval
Summary
Agricultural activities depleted more than 70% of the global consumed water, and these requirements are increasing by 90% in the developing countries with a permanent water shortages [5]. RESULTS AND DISCUSSION Anthesis (days): Results display in Table 1 indicate significant differences among the genotypes, irrigation intervals and EMS concentrations, as well as the interactions in the studied traits. The the highest value was obtained at genotypes required 72.86 days to anthesis the concentration 70 mM EMS accompanied under the longer irrigation interval. The significant effect of the irrigation intervals showed that plants of interaction of mutagen and irrigation intervals inbred line 5 under the irrigation interval of 9 had reflected on the used genotypes; the 18 days expressed the lowest days number inbred line reached 66 days under the EMS required for 50% anthesis (69.33 days), concentration of 60 mM and the 9 days exhibiting a significant differences among the irrigation interval, whereas, the interaction inbred line 18 which gave the highest mean of between the 70 mM of EMS and the longest. Results are in agreement with the results mM of EMS, while the inbred line 18 had the of recent studies [2] who reported that the highest mean (75.33 days) at the concentration number of days for anthesis depends on the of 70 mM to complete 50% anthesis. mutagenic concentration including EMS, in Genotypes were significantly affected by addition to the response of the genotypes
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