Percent change in root length, root projected area and root volume at different soil depths under different nitrogen treatments using the soil coring method and minirhizotron method.

Percent change in root length, root projected area and root volume at different soil depths under different nitrogen treatments using the soil coring method and minirhizotron method.</p

Correlations between root morphology indexes at the flowering and boll stage using the soil coring method and minirhizotron method.

<p>Correlations between root morphology indexes at the flowering and boll stage using the soil coring method and minirhizotron method.</p

Changes in root length density at different soil depths under different nitrogen treatments using the soil core method and minirhizotron method.

<p>Changes in root length density at different soil depths under different nitrogen treatments using the soil core method and minirhizotron method.</p

Comparison of sampling procedures using the soil coring method and minirhizotron method.

<p>Comparison of sampling procedures using the soil coring method and minirhizotron method.</p

Total root length density of cotton under different nitrogen treatments using the soil coring method and minirhizotron method.

<p>Total root length density of cotton under different nitrogen treatments using the soil coring method and minirhizotron method.</p

Monthly precipitation distribution and average soil temperature during the cotton growth period in 2014 and 2015 in Baoding (China).

<p>Monthly precipitation distribution and average soil temperature during the cotton growth period in 2014 and 2015 in Baoding (China).</p

Correlations between root morphology densities at shallow soil depth and deep soil depth measured using the soil coring method and minirhizotron method.

<p>Correlations between root morphology densities at shallow soil depth and deep soil depth measured using the soil coring method and minirhizotron method.</p

The germination of cotton seeds that received the M0, M20, and M200 melatonin treatments after 24 hours of germination (A), and the germination of cotton seeds treated with different concentrations of melatonin on the third day (B).

The germination of cotton seeds that received the M0, M20, and M200 melatonin treatments after 24 hours of germination (A), and the germination of cotton seeds treated with different concentrations of melatonin on the third day (B).</p

Effects of different melatonin concentrations on cotton seed germination rate (GR) and germination potential (GP).

Effects of different melatonin concentrations on cotton seed germination rate (GR) and germination potential (GP).</p

Effects of different concentrations of melatonin on contents of gibberellin (GA₃) (A) and abscisic acid (ABA) (B).

Effects of different concentrations of melatonin on contents of gibberellin (GA3) (A) and abscisic acid (ABA) (B).</p