Studies On Growth And Development Of Barley Mutant TL43

Triumph is a major malting barley cultivar (cv.) in Europe for many years. This genotype, although characterized by superior malting quality and yield and high resistance to lodging and mildew, has the disadvantage of being very prone to dormancy, a characteristic that has been frequently inherited by its progeny. Molina-Cano et al. induced a mutant named TL43 in Triumph by N₃Na solution, which germinated readily 2 weeks after harvest, was classified as ABA-insensitive, since it could tolerate a ten-fold increase in ABA compared to its parent. Now there had many reports about the effect of allele mutation on grain and malt quality in TL43 but little about the resistance to environmental stress as well as its growth and development characteristics. In the present research, TL 43 and its parent Triumph were used to investigate their resistance to water stress during seedling, the effect of applying nitrogen fertilizer at booting on photosynthesis characteristics in flag leaf, changes of four plant hormones in flag leaf and grain, changes of protein components in grain after anthesis with pot planting at Huajiachi campus of Zhejiang University in 2005. The main results were as follows: 1. Response of TL43 and Triumph under water stress during seedlingUnder water stress, the net photosynthesis rate and Fv/Fm value were reduced in the last full-expanding leaf, and the reduction extent in chlorophyll content increased with the leaf position descending, MDA content was accumulated and the activities of SOD and POD increased. Moreover, the plant hormone ABA content increased while IAA, GA, and ZR decreased. Finally, the plant height and dry matter weight decreased significantly when water stress treating finished at 28^th day.The resistance capability in Triumph was greater than that in TL43, and it could be embodied by the following: the reduction in net photosynthesis rate and Fv/Fm value in leaf were less in Triumph than that in TL43, in addition, the difference between water stress treatment and control in Triumph was also smaller until 21 days after treating. Moreover, the chlorophyll content in the last full-expanding leaf was almost the same to that in the control in Triumph before treating after 21 days and then decreased, meanwhile, the reduction in chlorophyll content in the second and third leaf from the top in waterstress treatment were also smaller in Triumph cultivar than those in TL43. When water stress treating finished at 28 days, the reduction on plant height and dry matter weight in drought or waterlogging treatment in Triumph was less than that in the corresponding treatment in TL43.It suggested that the MDA content accumulation in leaf in water stress treatments in Triumph was less than that in TL43 during the early period, while the time on which SOD and POD activities began to increase occurred later and still kept higher during the later period, but the enzymes activities were significantly lower in water stress treatment in TL43 when compared to the control at the same time. Furthermore, the increase in ABA content in Triumph was greater than that in TL43 under water stress. It could be argued that the differences in anti-oxidative stress and the response of ABA synthesize metabolism to water stress were the important reasons which resulted in the difference in resistance to water stress between Triumph and TL43.2. Effects of applying nitrogen fertilizer at booting stage on photosynthesis characteristics in flag leaf and grain weightApplying nitrogen fertilizer at booting stage increased the net photosynthesis rate, chlorophyll content and Fv/Fm value in flag leaf after anthesis, moreover, the increase were greater in Triumph than those in TL43, and the net photosynthesis rate in flag leaf in the two treatments in Triumph was higher that that in the corresponding treatment in TL43. Therefore, the grain weight in Triumph was significantly higher than that in TL43.3. Effects of applying nitrogen fertilizer at booting stage on plant endo-hormone contents in flag leaf and grainApplying nitrogen fertilizer at booting stage decreased ABA content, increased the contents of IAA, GA and ZR in flag leaf after anthesis, increased the contents of ABA and GA, however, it had little effect on IAA and ZR contents in grain during the grain filling.The decrease in ABA content and increase in IAA content in flag leaf when applying nitrogen were greater in Triumph than those in TL43, but it is contrary to the increase in ZR content. Moreover, the effect of applying fertilizer at booting stage on the four hormone contents in grain showed great differences between TL43 and Triumph.4. Effects of applying nitrogen fertilizer at booting stage on protein as well as its components content in grainApplying nitrogen fertilizer increased the total protein content in the two barley cultivars, and among those, the increase in TL43 was greater than that in Triumph. Applying nitrogen had no effect on the contents of albumin and globulin, but significantly increased gliadin and glutenin contents in Triumph, while increased the contents of albumin, gliadin and glutenin, decreased the globulin content in TL43 in which the increase in gliadin in TL43 was especially significant.The increase in total protein content in TL43 was significantly greater than that in Triumph when applying nitrogen fertilizer at booting stage.