Effects of Water Regulation on Growth, Physiology and Chlorophyll Fluorescence of two Maize Lines

Changes and responses of the physiological characteristics of two maize lines H242/1523 and H14/A18 to water regulation in the field were studied.Growth, physiology and photosynthetic parameters and chlorophyll fluorescence parameters of the maize lines have been investigated under low, medium and high irrigation levels.The results showed that, under three irrigation treatments, the phenotypic traits (plant height, stem diameter, SPAD value, number of leaves and stay-green ability), antioxidant enzymes (SOD activity and POD activity), osmoregulatory substances (soluble sugar and soluble protein) and yield indicators (dry forage yield and 100-grain weight) all were found higher in H242/1523 than H14/A18.However, the plant height and the number of leaves of H242/1523 were lower than H14/A18 under low water irrigation conditions.With the increase of irrigation amount, all the above indicators showed an upward trend.For cell membrane relative permeability (EL) and membrane lipid peroxidation product (MDA), H242/1523 was lower than H14/A18, and with the increase of irrigation level, the changes of EL and MDA were contrary to the above indicators.Based on the biordered graphs of the correlation matrix, there was a certain correlation between the variables.Among them, the plant height was highly positively correlated with leaf number and hay yield.SPAD values were highly positively correlated with stem diameter and stay-green ability, but SPAD values were negatively correlated with EL and MDA.There was a highly positive correlation between EL and MDA, but a very significant negative correlation with stay-green ability and hay yield.Soluble sugar content correlated highly and positively with SOD and soluble protein.Further analysis of the clusters of correlation matrix PCA, the results revealed that H242/1523 had strong drought resistance and H14/A18 had poor drought resistance.Therefore, H242/1523 is more suitable for cultivating and planting in water-deficient areas like Yellow River Irrigation Area of Ningxia.The maize line H242/1523 can also be provided as an excellent germplasm resource for the drought-resistant breeding program and water-saving cultivation research.