Table 1.

Equations of regressions lines fitted to relative plant growth and quality responses, and their relationships with leaf Na and Cl concentrations, in three crapemyrtle (Lagerstroemid) cultivars subjected to increasing NaCl stress. Data used in the regression procedures are presented in Figure 2 and Figure 3.

Response Variable	‘Pink Lace’	‘Natchez’			‘Basham’s Party Pink’
Response Variable	Growth and quality responses to applied NaCl^{^z}
Relative plant DW^{^y}		For all cultivars,	Y = 84.5 − 3.28X + 0.06X²	R² = 0.89
Relative root DW	Y = 76.2 − 1.35X + 0.01X²	R² = 0.92	Y = 79.6 − 4.85X + 0.12X²	R² = 0.98	Y = 91.6 − 5.29X + 0.12X²	R² = 0.86
Shoot: root ratio	Y = 2.61 + 0.02X − 0.003X²	R² = 0.94	Y = 3.94 + 0.09X − 0.004X²	R² = 0.75	Y = 2.29 + 0.08X − 0.002X²	R² = 0.70
Relative growth index	Y = 87.5 − 0.20X − 0.01X²	R² = 0.96	Y = 89.6 − 0.98X + 0.01X²	R² = 0.81	Y = 88.3 − 1.98X + 0.05X²	R² = 0.76
Chlorophyll index (SPAD)	Y = 70.1 − 0.94X − 0.01X²	R² = 0.99	Y = 55.1 − 0.76X − 0.01X²	R² = 0.96	Y = 58.3 + 0.27X − 0.01X²	R² = 0.36
Salt burn rating	Y = 0.465 + 0.166X	R² = 0.99	Y = 0.179 + 0.062X	R² = 0.99	Y = 0.064 + 0.038X	R² = 0.99
Relative plant DW and salt burn relationship to leaf Na
Relative plant DW	For all cultivars, Y = 81.9 − 0.021X + 2.5x10⁻⁶ X² R² = 0.68
Salt burn rating	Y = 0.403 + 0.0018X − 1.8x10⁻⁷X² R² = 0.90		Y = 0.222 + 0.0004X − 2.2x10⁻⁸X² R² = 0.91		Y = 0.017 + 0.0005X − 4.5x10⁻⁸X² R² = 0.77
Relative plant DW and salt burn relationship to leaf Cl
Relative plant DW	For all cultivars, Y = 16.8 + 240.1X − 240.7X² + 83.4X³ − 9.6X⁴ R² = 0.79
Salt burn rating	Y = 0.210 − 1.03X + 1.17X² R² = 0.69		Y = 0.102 + 0.10X + 0.12X² R² = 0.81		Y = 0.249 − 0.68X + 0.51X² R² = 0.65

↵^zFor equations: Y corresponds to the listed response (dependent) variable, while X denotes applied NaCl concentration or Leaf Na or Cl concentration (independent variables).
↵^yDW = Dry weight.