Measurement of growth and physiological indices
(1) Measurement of seedling growth indices:
Before planting the seedlings, the height of each seedling were measured
with a measuring tape (accuracy: 1 mm), respectively; the seedings were
tagged accordingly. The duration of the experiment was one year;
measurements of the plant height each seedling were repeated two weeks
before the end of the experiment.
(2) Measurement of seedings biomass accumulation indices:
The duration of the experiment was one year; At the end of the
experiment, each seedling was collected and finished in an oven at 110℃,
then dried to constant weight after being adjusted to 80℃. An electronic
balance with a precision of 0.01g was used to weigh the dry matter.
(3) Determination of antioxidant enzyme activities:
Antioxidant enzyme activities can reflect to a certain extent the
differences in the adaptability of plant seedlings to the environment
(Krauss, et al., 2014). Therefore, in this study, the amount of three
stress-related substances, including superoxide dismutase (SOD),
catalase (CAT), and malondialdehyde (MDA), were selected to determine
the seedling adaptability to environmental changes.
① SOD activity was determined by the nitrogen blue tetrazolium (NBT)
method. The total SOD activity (u·g-1) is determined
by the unit number of enzyme per unit of fresh weight, where one unit of
enzyme activity is defined as the amount of enzyme required to inhibit
NBT reduction to half of the control.
② CAT activity was measured by the ultraviolet absorption method. The
amount of enzyme that A240 reduces by 0.1 within 1 min is defined as one
enzyme activity unit (u·g-1·min-1).
③ MDA content was determined by the thiobarbituric acid (TBA) method.
The MDA content is expressed as the number of moles of MDA per unit of
fresh weight. The unit is µmol·g-1.
The absorbance values of the above enzymes were all measured using the
Lambda 35 UV/VIS spectrometer (Perkin Elmer, USA).