Average activities of sucrose phosphate synthase (SPS), sucrose synthase (SuSy), acidic invertase (Acidic INV) and alkaline invertase (Alkaline INV) in cotton fiber during fiber secondary wall rapid-thickening (FSWR) and their analysis of variance under the coupling of planting date and shading in

FW, fresh weight; Values in the same planting date followed by the different letters within a column are significantly different at 0.05 probability level; CVS was calculated from the data of three shading treatments in normal planting date of 25 April, CVP was calculated from the data of three planting dates and CVP×S was calculated from the data of all treatments; * and ** mean significant difference at 0.05 and 0.01 probability levels, respectively; NS means non-significant differences.