ارزیابی نمونه‌های ژنتیکی بومی ارزن معمولی(.Panicum miliaceum L) ایران در شرایط تنش شوری

This study was carried out to identify salinity tolerance in native common millet accessions of Iran. A set of 168 accessions of common millet (Panicum miliaceum L.) conserved in the National Plant Gen Bank of Iran were evaluated in 2020 growing season under salinity stress conditions (irrigation water with EC of 8 dS m^-1) in Agriculture and Natural Resources Research and Education Center of South Khorasan, Birjand, Iran. The superior 30 accessions of common millet toghether with Birjand landrace were selected for planting in 2022 grwoing season. The experimental design for evaluation of selected accessions was randomized complete block design with three replications and undertwo conditions (irrigation water with EC =3 ds m^-1 and EC = 8 ds m^-1). Analysis of variance, correlation, regression, K-means cluster analysis, factor analysis, and biplot were used for processing of data. Leaf water status (RWC, WSD, WCS, LTD) and tolerance and susceptible indices (STI, NP, TOL, HM, GMP, SSI, YI, YSD, STS) were calcualted and used in the analyses. Grain yield varied from 200 kg ha^-1 in accession 15-19 to 4600 kg ha^-1 in accession 15-192. Mean comparisons of leaf water status indices grouped the accessions alike grain yield. Biplot based on two first factors of factor analysis identified the best accessions with high mean grain and dry forage yields. Cluster analysis reveleaed the same results. Based on this findings, accessions 15-23, 15-49, 15-223, 15-192, Ferdous (91) and native Birjand accessions, which had high grain yield, also showed high relative water content (RWC) were identified as salinity stress tolernat. These accessions can be used for development of salinity toerant germplasm in the national common millet breeding program.
 
Keywords: Common millet, leaf water stutus, cluster analysis, dry forage yield, grain yield.
 
Introduction
There is a collection of common millet (Panicum miliaceum L.) accessions in Iran, which has been collected and conserved in the National Plant Gen Bank of Iran (Abbasi et al., 2024). The short life-cycle duration and C4 type photosynthesis system of common millet makes it suitable for be grown in the marginal lands. Considring climate change, decreasing in precipitation and its irrugalr distrubation, scarcity of irrigation water, and increasing temperatures in Iran, it necessiates to search for some suitable alternative crops adapted to developing environmental conditions in cropping systems. Millets including common millet are suitable candidates for cultivation in such conditions. Salinity tolerance in some common millet germplasm have been conducted in Iran. Kafi et al. (2009) showed that 21% decreasing in grain yield of common millet under 5.5 ds m^-1 salinity stress conditions. Alizadeh Bonab et al., (2007) reported that 100 mM NaCl significantly affected studied common millet germalsm, and shoot and root dry matter significantly decreased. However, complete set of common millet accessions colleaction of the National Plant Gen Bank of Iran has not been evaluated for salinity tolerance.
This study carried out to identify water salinity tolerance of complete set of common millet accessions of Iran for being used as parents for development of salinity tolerant germplasm in common millet breeding programs.
 
Materials and Methods
 A complet set of 168 common millet accessions of the National Plant Gen Bank of Iran were planted in a field experiment and irrigated with water with 8 ds m^-1 in Agricutural and Natural Resources Research and Education Center of South Khorasan, Birjand (E 58º 59', N 32º 52', with elevation of 1381 m above sea levle) using augmented design in 2021. Field soil texture was sandy-loam. Each accession was planted in two rows with two meters length and 50 cm row spacing. Agronomic and phenological traits were measured and recorded. Based on grain yield and some more traits (panicle length, panicle shape and lodging), 30 accessions were selected for being grown in 2022.
 In 2022 growing season, selected accessions were planted in two separate experiments (None-stress irrigated with 3 ds m^-1 and salinity stress irrigated with 8 ds m^-1 irrigation water) using randomized complete block design with three replications. Each accession was planted in two rows with two meters length and 50 cm row spacing.
Days to flowering and maturity, plant height, width and length of flag leaf, plant pubescence, panicle length, 100-grain weight, grain and forage yields were measured and recorded. Leaf water status, relative water content (%RWC), water content saturation (WCS), Water saturation deficiet (WSD%), Leaf tissue density (LTD) were estimated and used in the analyses following Smart and Bingham (1974).
Stress tolerance and susceptible indices (STI, NP, TOL, HM, GMP, SSI, YI, YSD, STS) were calculated based on grain yield and dry forage yield. Anaysis of variance, correlation, regression, K-means cluster analysis, factor analysis, and biplot were used for analysis of data. Excle and SPSS softwares were employed for statistiscal analyses.
 
Results and Discussion
In 2021 experiment, grain yield varied from 170 kg ha^-1 to 3920 kg ha^-1. The results of this experiment showed that there were high variation for tolerance to salinity among the common millet accessions. Based on grain yield and other agronomic traits 30 accessions were selected for second year experiment in 2022. In this experiment, grain yield varied from 300 kg ha^-1 in accessions 15-288 to more than 4600 kg ha^-1 in accession 15-192.
Mean comparisons of leaf water status indices grouped the accessions alike grain yield. Based on these traits, the accessions 15-49, Ukrainian, 15-223, Ferdous (91) and native Birjand, which had high grain yield, and also high relative water content (RWC) were identified as salinity tolerant. Correlation analysis showed significant correlation coefficiens between grain yield and dry forage yield (r = 0.729, p<0.01). This finding is in accordance with reported result by Yazdizadeh et al., (2020). There was significant correlation cofficients between salinity tolerance score and days to maturity.
 Biplot based on the two first factors of factor analysis identified the superior accessions, which had salinity tolerance and high grain and dry forage yields. When grain yield-RWC biplot or grain yield- salinity tolerance score biplot were drawn, the results were alike. Cluster analysis also showed similar results.
 In conclusion, accessions 15-49, 15-23, 15-223, Ferdous (91) and Birjand landrace were identified as salinity tolerant. These accessions can be used for development of salinity toerant germplasm in that national common millet breeding program.
 
References
Abbasi, M.R. Amirabadizadeh, H., Nakhaei, A., […], Beheshti, A., Pourpayghambar, M. and Mehrani, A. 2024. Seed collection and evaluation of Iranian millets genetic resources. Iranian Journal of Seed Sciences and Research, 11(1), pp.1-14 (in Persian). DOI: 10.22124/jms.2024.8035.
Alizadeh Bonab, G., Ghasemi, G.K. and Taghizadeh, S. 2007. Investigation of salinity and temperature effects on germination, seedling growth and ion relation of Panicum miliaceaum. Pazhouhesh va Sazandegi, 74, pp.115-122. (in Persian).
Kafi, M., Zamani, Gh. and Ghoraishi, S.Gh. 2009. Relative salt tolerance of south Khorasan millets. Desert, 14(1), 63-70.
Smart, R.E. and Bingham, G.E. 1974. Rapid estimates of relative water content. Plant physiology, 53(2), pp.258-260.
Yazdizadeh, M., Fahmideh, L., Mohammadi-Nejad, G., Solouki, M. and Nakhoda, B. 2020. Association analysis between agronomic traits and AFLP markers in a wide germplasm of proso millet (Panicum miliaceum L.) under normal and salinity stress conditions. BMC Plant Biology, 20(1), e427. DOI: 10.1186/s12870-020-02639-2