Genotypic differences in soybean yield responses to increasing temperature in a cool climate are related to maturity group

Abstract

To adapt soybean production to climate change, a thorough understanding of its response to high temperature is required. Modeling studies have predicted that high temperature would shorten the growth period and hence lower seed yield of less day length-sensitive (early-maturing) soybean cultivars, whereas the magnitude of yield reduction by high temperature would be smaller in cultivars with higher day length sensitivity (late-maturing), suggesting that late-maturing cultivars would benefit from a future high-temperature environment. Current mean growing season temperature ranges from 19.4 to 22.6 degrees C in the northern, cool regions of Japan, which is near or below the reported optimum temperature (22-24 degrees C) for seed yield. We tested the hypothesis that adaptation by growing late-maturing cultivars will be successful in maintaining seed yield under a cool climate when temperature is increased during 21st century. We used three Japanese soybean cultivars, early-maturing Yukihomare and late-maturing cultivars Ryuhou and Enrei. Plants were grown over 3 years from June to September (a conventional season) under three temperature regimes, T1 (ambient), T2 (1.8-3.6 degrees C above ambient), T3 (4.8-5.7 degrees C above ambient), in a sunlit temperature gradient chamber. The leaf area at the full expansion stage, pod and seed numbers, and seed yield increased at elevated temperature in the late-maturing cultivars but not in the early-maturing one. The photosynthetic rate and effective quantum yield of photosystem II at the flowering stage increased at elevated temperature in all three cultivars. The period from sowing to the beginning of flowering (R1) decreased in all three cultivars at elevated temperature, whereas the period from R1 to the beginning of pod addition and the flowering period were prolonged in the late-maturing cultivars, but not in the early-maturing one. The differential response in post-flowering development in different maturity groups is probably related to the differences in the day length requirements of these cultivars. Our data clearly demonstrate that yield enhancement by increasing temperature in the late-maturing cultivars resulted from both the improvement in sources (leaf area and leaf photosynthesis) and the increase in sink size (number of flowers, pods and seeds) due to the longer flowering period. We conclude that the yield of the late-maturing cultivars sown during the conventional season in the cool regions of Japan will increase during the 21st century. (C) 2014 Elsevier B.V. All rights reserved

Calibration, uncertainties and use of soybean crop simulation models for evaluating strategies to mitigate the effects of climate change in Southern Brazil

“…Contrasting with the MONICA results, Kumagai and Sameshima (2014) observed that a cultivar with a longer flowering period and, consequently, longer complete cycle, had higher yield, due to increased leaf area, photosynthesis and number of flowers, pods and seeds. This was not observed when using MONICA model because the maximum effective root depth was limited to 0.75 m during the calibration, a condition that led to increased yield penalization by water deficit in the longer cycles of maturity groups 6.8 and 7.8 (SPEHAR et al, 2015).…”

“…The reduction of yield is attributed mainly to the shorter crop cycle, as also observed by and Kumagai and Sameshima (2014). The only exception was for FAO model that had a slight positive response, between 2 e 21 kg ha -1 °C -1 in some specific conditions (site x temperature increase) ( Table 3).…”

“…Regarding crop maturity group, Kumagai and Sameshima (2014) demonstrated that late-maturity cultivars increase yield under climate change in cool regions of Japan, explicitly, due to the post-flowering day-length requirement extending the reproductive period, once the beginning of flowering was accelerated by higher temperatures in late and early-maturity cultivars. On the other hand, Kassie et al (2015) showed that under current and only wet-scenario future climate does a medium-cycle cultivar has significantly greater yield than a short-cycle maize cultivar, showing that an increased occurrence of water deficit penalizes both of them.…”

Estimated length of soybean phenological stages

“…The simulations on air temperature changes shows a direct influence on the phenological stages duration in soybean. Kumagai and Sameshima (2014) detected that the duration from days of sowing to the beginning of soybean flowering decreased with an increase in temperature for all studied cultivars. Thus, an increase of the flowering period with a consequently increase in the number of open flowers, could result in an increase in pods and grains for late maturity cultivars.…”

Effect of early sowing on growth and yield of determinate and indeterminate soybean (<I>Glycine max</I> (L.) Merr.) cultivars in a cool region of northern Japan

“…The inhibition of seedling emergence and therefore of canopy development that occurs at low temperatures was not observed in any year, even in 2013, when the May weather was slightly colder than the long-term average. As Horai et al 2013 Kumagai et al 2012, Kumagai andSameshima, 2014;Kumagai et al, 2015 . I hypothesize that early sowing may be more successful in the future and that soybean production will therefore increase if temperatures continue to increase in this region owing to global warming.…”