Direct and indirect measurements of freezing tolerance: advantages and limitations

Abstract

The freezing tolerance of 69 accessions of field-grown, common wheat (Triticum aestivum) was assessed in three consecutive winters. To measure freezing tolerance directly, field-grown plants were subjected to a range of freezing temperatures in a controlled environment and plant regrowth was subsequently assessed. Indirect assessments of freezing tolerance, as measured by chlorophyll fluorescence transient measurements followed by a JIP-test (an in vivo measurement of the adaptive behavior of the photosynthetic apparatus), were performed on detached leaves frozen at the same time as whole plants. Both direct and indirect tests were also used on plants cold acclimated in the laboratory. These results were compared with results of a field survival study performed at seven experimental sites. An analysis of the data indicated that only some of the JIP-test parameters were suitable for the prediction of freezing tolerance and winter survival. Estimates of cold hardiness were very similar, regardless of the experimental year, but were dependent on the method of cold acclimation and time of sampling. Indirect measurements of cold hardiness were more in line with the field survival data for field-cold-acclimated plants sampled in mid-winter than for plants that were either sampled earlier or cold acclimated in the laboratory. Indirect measurements taken on leaves that had not frozen failed to provide accurate estimates of cold hardiness. Our observations, together with previously reported findings, indicate that cold acclimation under natural field conditions activates a greater array of freezing tolerance mechanisms than cold acclimation performed in under controlled environmental conditions in a laboratory.

Is the OJIP Test a Reliable Indicator of Winter Hardiness and Freezing Tolerance of Common Wheat and Triticale under Variable Winter Environments?

“…The OJIP test also provides information about the probability of the fate of absorbed light energy as well as detailed information on photosynthetic apparatus structure and function [ 8 ]. Recent studies of photosynthetic apparatus response to freezing based on the OJIP test have shown that the chlorophyll fluorescence techniques used to predict whole-plant freezing tolerance and, ultimately, winter hardiness are advantageous, but also have interesting limitations that make the reliability of the results dependent on certain conditions [ 15 – 17 ]. Although cold-induced changes in the photosynthetic apparatus are necessary for whole-plant cold acclimation [ 18 , 19 ], freezing tolerance in the field depends on many factors based on complex environmental responses [ 20 ].…”

“…Although cold-induced changes in the photosynthetic apparatus are necessary for whole-plant cold acclimation [ 18 , 19 ], freezing tolerance in the field depends on many factors based on complex environmental responses [ 20 ]. This complexity makes the results of chlorophyll fluorescence-based studies more difficult to understand, but can provide a unique opportunity to distinguish the effects of different environmental factors on freezing tolerance in the field [ 17 ].…”

“…Previous studies conducted on common wheat ( Triticum aestivum L.) or triticale (× Triticosecale Wittm. ), the most widely cultivated winter cereals in Poland, indicated that not all OJIP-test parameters were related to the freezing-tolerance level of the investigated plants [ 15 , 17 , 21 , 22 ]. In addition, the usefulness of a given parameter seemed to depend on environmental conditions before sampling, freezing temperature or even plant species.…”

Analysis of Cold-Developed vs. Cold-Acclimated Leaves Reveals Various Strategies of Cold Acclimation of Field Pea Cultivars

“…Then, despite the fact that END does not bear the characteristics of the genuine winter cultivar suitable for European continental winters, it might be useful for further research oriented toward winter cultivars of afila type. Nevertheless, we still should keep in mind that further factors, such as the responsiveness to the photoperiod [42], also play a prominent part in winter resilience (for a review see, e.g., [43]), and that cold acclimation in laboratory conditions does not always reflect real winter hardiness [44]. Further tests are thus needed, including a winter survival test in the field, to support this idea.…”

Frost tolerance, regeneration capacity after frost exposure and high photosystem II efficiency during winter and early spring support high winter survival in Juncus spp.

“…Chlorophyll fluorescence analysis is a non-destructive method that can be used to study the performance of the photosynthetic apparatus (PSII) in plants. The fluorescence parameter F v /F m expresses the maximum quantum yield of PSII and may be used as a stress indicator (Maxwell & Johnson, 2000), and several fluorescence parameters may be related to stress responses (Rapacz et al, 2015).…”