Heat stress during seed filling interferes with sulfur restriction on grain composition and seed germination in oilseed rape (Brassica napus L.)

Abstract

In coming decades, increasing temperatures are expected to impact crop yield and seed quality. To develop low input systems, the effects of temperature and sulfur (S) nutrition in oilseed rape, a high S demanding crop, need to be jointly considered. In this study, we investigated the effects of temperatures [High Temperature (HT), 33°C/day, 19°C/night vs. Control Temperature (Ctrl T), 20°C/day, 15°C/day] and S supply [High S (HS), 500 μm SO2−4 vs. Low S (LS), 8.7 μM SO2−4] during seed filling on (i) yield components [seed number, seed dry weight (SDW) and seed yield], (ii) grain composition [nitrogen (N) and S contents] and quality [fatty acid (FA) composition and seed storage protein (SSP) accumulation] and (iii) germination characteristics (pre-harvest sprouting, germination rates and abnormal seedlings). Abscisic acid (ABA), soluble sugar contents and seed conductivity were also measured. HT and LS decreased the number of seeds per plant. SDW was less affected due to compensatory effects since the number of seeds decreased under stress conditions. While LS had negative effects on seed composition by reducing the FA contents and increasing the ratio S-poor SSPs (12S globulins)/S-rich SSPs (2S albumins) ratio, HT had positive effects by increasing S and FA contents and decreasing the C18:2/C18:3 ratio and the 12S/2S protein ratio. Seeds produced under HT showed high pre-harvest sprouting rates along with decreased ABA contents and high rates of abnormal seedlings. HT and LS restriction significantly accelerated germination times. High conductivity, which indicates poor seed storage capacity, was higher in HT seeds. Consistently, the lower ratio of (raffinose + stachyose)/sucrose in HT seeds indicated low seed storage capacity. We demonstrated the effects of HT and LS on grain and on germination characteristics. These results suggest that hormonal changes might control several seed characteristics simultaneously.

Foliar application of sodium hydrosulfide (NaHS), a hydrogen sulfide (H2S) donor, can protect seedlings against heat stress in wheat (Triticum aestivum L.)

“…4, exogenous NaHS could lead to significant accumulation of soluble sugar under heat stress conditions. The result is consistent with the results of previous studies (Gomathi et al 2013;Brunel-Muguet et al 2015). The positive modulation of exogenous H 2 S donor (NaHS) in sol-uble sugar accumulation might also contribute to enhanced stress tolerance.…”

Allelopathic effects of humus forest soil of Hippophae rhamnoides, Caragana korshinskii and Amorpha fruticosa on medicinal plants

“…The possible reason is that allelochemicals with selectivity and specificities which come from same kind of humus soil can effect seed germination of different medicinal materials and from different kinds of humus soil can effect seed germination of same medicinal material (Yang et al, 2005;Ma et al, 2006), which was supported by the findings of Guo et al (2010) who stated that the leaf water extracts from A. fruticosa show allelopathic inhibition effect on the seed germination and seedling growth of soybean and fababean. And also allelochemicals affected seed cell membrane permeability, cell division and differentiation, respiration, protein synthesis, gene expression, and hormone synthesis and equilibrium (Brunel-Muguet et al, 2015). Nevertheless, in this study, the humus soil from C. korshinskii inhibited the seed germination of Glycyrrhiza uralensis, which is not in line with the findings of Sun et al (2008), who reported that C. korshinskii roots leaf water extract caused significantly inhibition on the seed germination of Glycyrrhiza uralensis.…”

The Importance of Ion Homeostasis and Nutrient Status in Seed Development and Germination

“…Finally, the positive repercussion of an adequate fertilization ameliorating climatic change effects on seed filling should be considered. Thus, it has been shown in oilseed rape that the control of S fertilization under heat stress improved grain quality and reduced the detrimental effects of climate change [56].…”