The decrease in tuber growth rate
caused by moderate water deficit was more marked and significant during the first than the
second planting, as shown by the significance of linear regression slope (P < 0.001)
between tuber growth against time (b = 7.3 and 11.9 for 50 and 100% ETM, respectively, in first planting; b = 12.4 and 15.4 for 50 and 100% ETM, respectively, in second planting).
Spunta showed a higher tuber growth rate than Sieglinde in both plantings (Fig. 7).