Abstract:
In this study, we measured the predawn maximum photochemical efficiency of photosystem Ⅱ (
Fv/
Fm) in the leaves of 60 sugarcane breeding materials during an extreme low-temperature period. We also measured leaf anatomical structure, specific leaf area (
SLA), and leaf resistance to punch (
Fp), and analyzed the correlation between structural traits and cold tolerance. Results showed that during the coldest period in winter, 55 of the 60 samples showed cold damage (
Fv/
Fm < 0.7), including 35 cultivars with
Fv/
Fm < 0.6.
Fv/
Fm was negatively correlated with the lowest temperature in the coldest month and average temperature in the cold season of the source site of the breeding material.
Fv/
Fm was positively correlated with mesophyll thickness (MT) and leaf resistance to punch (
Fp). We found that sugarcane cultivars with stronger cold tolerance had larger MT and
Fp. Thus,
Fp could be used as an important index for screening cold tolerance in sugarcane cultivars.