Changes of husk leaf water potential of maize and relationship with environmental factors in black soil region of North-East China.

The variation of husk leaf water potential (HLWP) in maize (Zea mays L.) and its relationship with environmental factors in black soil of North-East China were analyzed in this study. The experiment was carried out at the Agricultural Experimental Station in Dehui, Jilin province. Two varieties, ZD 958 and ND 364 were planted in the field. The HLWP was measured by PSYPRO water potential apparatus during the key growing stages of maize. The diurnal change trend of HLWP was in a shape of parabola. The water potential was higher in the morning and the evening, and lower in the midday, with the highest value at 6:00 am and the lowest value at 10:00 am. Diurnal average HLWP for ZD 958 was lower than that for ND 364, while the change range of the former was higher than that of the latter. HLWP and relative water content (RWC) were declining along with the growing of maize, the change of water saturation deficit (WSD) was opposite. A linear relationship occurred between HLWP and WSD: y=A+Bx. The constant A for ZD 958 was less than that for ND 364, indicating that the former had lower WSD and higher RWC than the latter under normal water condition. ZD 958 had a smaller slope, which showed that WSD was affected less by water potential unit dynamics. Therefore, the dehydrate rates were relatively slower in husk leaves of ZD 958 under drought stress. There was a negatively significant correlation between HLWP and air temperature (TA) as well as a positively significant correlation between HLWP and relative atmospheric humidity (RH). No significant correlation was found between HLWP and photosynthetic active radiation (PAR).