Response of some rice varieties to different doses of X rays on the yield and its related characters

This experiment was carried out at the experimental farm of Sakha Agricultural Research Station, Kafr Elsheikh , Egypt during 2016 and 2017 seasons, the materials including six rice varieties treated with three doses of X rays. The experimental design was a split plot design, the main plots were devoted to doses of X-rays, while, sub plots were devoted to rice varieties with three replications, the date of sowing for M₁ was after seed treated during May 1^st 2016 and M2 was planted in 1 ^st May during 2017 season, the data were recorded on total duration, plant height and yield components. The results showed that all the studied characters affected by different doses of X rays and the dose (300 Kr) recorded the desirable values for most studied characters. Moreover, the variety Giza 171 was highly affected by the different doses of X rays, whereas, the high dose of X rays recorded the shortest plant height compared to Giza 159. Also, GZ6296 was highly affected by different doses of X rays especially for seed set % which referred to the genetic makeup (Indica / japonica) for this line indicating the occurrence of some rearrangement for the genetic background.  On the other side, M₂ generation recorded highest values for all the studied characters of all the treated varieties compared to M₁ generation, meaning that, during M₂ generation some different rearrangement was occurred on the molecular levels for the genetic structure of the rice varieties thus exchanging the gene expression for the morphological and yield characters. In M₁ generation over the all genotypes, irradiation doses significantly decrease most of the studied characters; in contrast, total duration and plant height were significantly increased by irradiation treatments in M₁ generation. In M₂ generation the irradiation doses significantly increased the mean value over all the genotypes for number of panicles/ plant, panicle length, panicle weight, seed set %, 1000 grain weight, grain yield / plant and harvest index %, vice versa for total duration and plant height decreased . Genotype x dose treatment interaction was significant for all the traits, these results suggested, that promising lines of the varieties Giza 171 and Giza 159, E. Yasmin could be used to improve some characters such as, short stature, early maturity and highly grain yield.