Investigating the effect of different planting methods and different levels of hormone distribution on Flag leaf anatomy of rice genotypes under salinity stress in northern Khuzestan

Increased drought to maintain the water potential in plant causes a reduction in diameter of Xylem vascular bundles (Majd et al., 2009). Xylem vascular bundles area decreases in different conditions leading to water stress in order to improve irrigation efficiency and to maintain plant water potential (Limouchi & Farahvash, 2014). Stresses can decrease vascular bundles area and diameter to improve water use efficiency and to reduce transpiration, while these traits are positively and significantly correlated to grain yield (Limouchi, et al., 2013). Water shortage for rice leads to a reduction in the value of anatomical traits effective in water retention and movement such as vascular bundles to maintain the amount of water in rice (Dawood, 2016). This study aimed to identify the tolerance and sensitivity mechanisms to drought in different irrigation intervals in order to increase grain yield by examining changes in anatomical characteristics of leaf stamen.

This study was performed by split-split plots using randomized complete block design with three replications in Khuzestan province with the aim of determining the best Planting pattern and Hormone Treatment of rice cultivation in two years (2018 and 2019). Three planting methods (planting drying, planting seedlings, planting direct or common), 16 different levels of auxin and salicylic acid hormones in the form of seed priming and different leaf spray treatments with 1 and 2 liters per hectare and different spraying times in the tillering stages and The appearance of panicle on different rice genotypes was investigated.

The combined analysis results showed that in addition to the interaction effect of planting method in hormone traits, the level of large vascular bundles in other cases, the main and interaction effects of traits, there is a significant difference in the level of probability of one percent. The highest level of vascular groups in seedling cultivation was obtained due to optimal management and priming with auxin and salicylic acid due to the greatest effect on the plant. Also, the level of these traits was lower in genotypes with higher resistance, which can be one of the main mechanisms of the plant in terms of increasing adaptability and maintaining more water potential within the plant under stress conditions. Finally, the highest levels of large and small vascular panicle with mean 12348 and 1928.792 micrometers were obtained in IR 80508-B-194-3-B genotypes and red spider in the said treatments, respectively. The surface of large vascular bundles had the highest positive and significant correlation (0.124**) with grain yield in terms of its high level in water and food transfer. The obtained results can be one of the main goals in breeding research and modification of cultivars with higher resistance to salinity conditions under the influence of different hormonal treatments and planting patterns.

The results of this study showed that an increase in Hormone and irrigation intervals and thus increased drought had reduced vascular bundles area, which can be a mechanism to maintain water and cells turgidity pressure.Keywords: salinity stress, Rice, Vascular, Planting pattern, Hormone, Priming, Leaf.References:Dawood, M.G. 2016. Influence of osmoregulators on plant tolerance to water stress. Scientia Agriculturae, 13 (1): 42-58. Limouchi, K. 2013. Effect of Different Planting Dates on the Anatomy of the Flag Leaf and Grain Yield of Rice Varieties in the Khuzestan Region, Iran. International Journal of Biology, 2 (2): 19-27. (in Persian with English abstract).Limouchi, K., and Farahvash, F. 2014. Effect of different planting dates on anatomy of the peduncle and grain yield of rice varieties in the north Khuzestan region. India Journal of Sciences Research and Technoloji, 2 (2): 99-103. (in Persian with English abstract).Majd, A., Jonobi, P., and Zanipour, M. 2009. Effects of drought stress on anatomical structure of the sunflower plant. Developmental Biology, 1 (4): 11-24.