Abstract:

【Objective】To screen excellent millet varieties suitable for planting in the dry farming area of the Loess Plateau in Inner Mongolia.【Methods】Using 8 millet varieties as research objects and split plot experiment design，two treatments of pre-seedling supplementary irrigation and water deficit were set up. The growth characteristics and photosynthetic characteristics of millet varieties were compared and analyzed by principal component analysis.【Results】Pre-seedling supplemental irrigation significantly affected the growth and photosynthetic characteristics of millet varieties. Compared with water deficit treatment，Jinmiao K1 had the highest （6.56%） seedling emergence rate，followed by Zhangzagu No. 13（4.44%）；Jinmiao K1 and Zhangzagu No. 13 had better plant height performance，at 30.5 cm and 30.3 cm，respectively，increased by 15.21% and 6.27% and were significantly different from other varieties（P<0.05）；Zhangzagu No. 13 had better stem diameter and dry matter accumulation at 5.45 mm and 0.598 g，respectively，increased by 12.60% and 5.65%，and were significantly different from other varieties（P<0.05），followed by Jinmiao K1，which increased by 16.56% and 4.98%，respectively. Under the water deficit treatment，the leaf area index of Zhangzagu No. 13 and Jinmiao K1 were less affected by drought at 0.94 and 0.83，respectively；the relative chlorophyll content of Zhangzagu No. 13 was the highest at 51.18. The stomatal conductance of Zhangzagu No. 13 and Jinmiao K1 was better under both treatments，significantly higher than that of other varieties（P<0.05），4.45% and 4.36% higher under pre-seedling supplemental irrigation treatment than water deficit treatment，respectively. The net photosynthetic rates of Jigu 168 and Jinmiao K1 were significantly higher than that of other varieties（P<0.05）. Under water deficit treatment，Zhangzagu No. 13 had the best net photosynthetic rate at 33.18 μmol/（m²·s），which was 1.99% lower than that of pre-seedling supplementary irrigation. The transpiration rates of Zhangzagu No. 13 and Jinmiao K1 were better and significantly higher than that of other varieties（P<0.05），4.39% and 3.79% higher under pre-seedling supplemental irrigation treatment than water deficit treatment，respectively. Zhangzagu No. 13 and Jinmiao K1 had better water use efficiency under both treatments. Water deficit led to an increase in leaf photosynthetic water use efficiency，the two varieties increased by 11% and 7%，respectively.【Conclusion】Zhangzagu No. 13 and Jinmiao K1 could be promoted as the dominant varieties of millet for drought resistance and seedling protection in the dry farming area of the Loess Plateau in Inner Mongolia.

Key words: Millet varieties, Pre-seedling supplementary irrigation, Seedling stage, Agronomic traits, Photosynthetic characteristics, Principal component analysis