Fig. 3

Chlorophyll index (SPAD units), thylakoid membrane damage (F_o/F_m ratio; unitless) and components of seed yield per plant as a function of quantum yield of PSII (ΦPSII; unitless) under drought stress in wheat-alien chromosome lines (water withheld for 16 d). The CS check is shown as a white circle. The curve is fitted by a linear function. (a) chlorophyll index, y = 25.0 + 24.1x; r² = 0.13 (P < 0.05); (b) thylakoid membrane damage, y = 0.424–0.328x; r² = 0.33 (P < 0.001); (c) seed set percentage, y = 8.1 + 94.7x; r² = 0.42 (P < 0.001); (d) individual seed weight, y = − 4.21 + 105.2x; r² = 0.39 (P < 0.001); (e) seed yield per plant, y = − 0.396 + 3.61x; r² = 0.42 (P < 0.001) and (f) harvest index, y = − 5.61 + 48.83x; r² = 0.49 (P < 0.001)