Effects of Short Periods of Drought and High Temperature on Grain Growth and Starch Accumulation of Two Malting Barley Cultivars

1996 ◽  
Vol 23 (2) ◽  
pp. 201 ◽  
Author(s):  
R Savin ◽  
ME Nicolas

Short periods (3-5 days) of high maximum temperature (>35�C), often accompanied by drought, commonly occur during grain filling of cereals. Short periods of high temperature have been shown to reduce grain weight and baking quality in wheat, but little is known about their effects on barley. Consequently, we examined the effects of high temperature and drought, alone or combined, on grain growth for two barley cultivars, Schooner and Franklin. Treatments started 15 days after anthesis and consisted of the factorial combination of three temperatures and three water regimes. The high temperature (maximum 40�C for 6 h day-1) and drought treatments were maintained for 5 or 10 days. Drought reduced individual grain weight much more (ca 20%) than high temperature (ca 5%) for both cultivars. Franklin appeared to be more sensitive to heat stress than Schooner. The reduction in individual grain weight was greatest when both stresses were combimed (ca 30%). The reduction in mature grain weight under high temperature was due to a reduction in duration of grain growth for Schooner and to a reduction in both rate and duration of grain growth for Franklin (8-12%). The reduction in duration of grain growth was the most important cause of reduced grain weight at maturity under drought alone (12-25%) or combined with high temperature (25-33%). Nitrogen content per grain was quite high and similar for all treatments, and nitrogen percentage increased when stress was severe enough to reduce starch accumulation, confirming that starch accumulation is more sensitive to post- anthesis stress than nitrogen accumulation. We conclude that drought, particularly when combined with high temperature, is more likely than heat stress to cause large reductions in grain weight of barley under field conditions.

1997 ◽  
Vol 48 (5) ◽  
pp. 615 ◽  
Author(s):  
Roxana Savin ◽  
Peter J. Stone ◽  
Marc E. Nicolas ◽  
Ian F. Wardlaw

In this study, controlled-environment conditions were used to compare the effects of moderately high and very high temperatures during grain filling on grain growth and malting quality of barley. Heat stress applied from 15 to 20 days after anthesis (DAA) reduced grain weight by about 35%, whereas longer periods (15–20 days) of moderately high temperature applied from 20 DAA to maturity reduced grain weight by about 6%. Both heat stress and moderately high temperature resulted in reduced grain weight through a reduction in the duration of grain filling. Grain composition was altered by both moderately high and very high temperatures, although the changes were larger under very high temperatures. In general, there was a decrease in starch content, resulting from the reduction in both volume and number of A- and B-type starch granules. Nitrogen concentration was significantly increased only in the 30/25°C treatments, and changes in diastatic power were only minor. There was a reduction in β-glucan content, together with an increase in β-glucan degradation. However, malt extract was not significantly affected by these stresses.


1996 ◽  
Vol 23 (6) ◽  
pp. 739 ◽  
Author(s):  
PJ Stone ◽  
ME Nicolas

Short periods of very high temperature (> 35�C) are common during the grain filling period of wheat, and can significantly alter mature protein composition and consequently grain quality. This study was designed to determine the stage of grain growth at which fractional protein accumulation is most sensitive to a short heat stress, and to examine whether varietal differences in heat tolerance are expressed consistently throughout the grain filling period. Two varieties of wheat differing in heat tolerance (cvv. Egret and Oxley, tolerant and sensitive, respectively) were exposed to a short (5 day) period of very high temperature (40�C max, for 6 h each day) at 5-day intervals throughout grain filling, from 15 to 50 days after anthesis. Grain samples were taken throughout grain growth and analysed for protein content and composition (albumin/globulin, monomer, SDS-soluble polymer and SDS-insoluble polymer) using size-exclusion high-performance liquid chromatography. The timing of heat stress exerted a significant influence on the accumulation of total wheat protein and its fractions, and protein fractions differed in their responses to the timing of heat stress. Furthermore, wheat genotype influenced both the sensitivity of fractional protein accumulation to heat stress and the stage during grain filling at which maximum sensitivity to heat stress occurred.


1998 ◽  
Vol 49 (8) ◽  
pp. 1287 ◽  
Author(s):  
M. A. B. Wallwork ◽  
S. J. Logue ◽  
L. C. MacLeod ◽  
C. F. Jenner

Short periods of high temperatures (up to 35°C) during mid grain filling appear to reduce yield and quality in barley. Plants of 3 malting barley varieties, Schooner, Arapiles, and Sloop (a new South Australian malting variety), were grown under constant environment conditions from germination to maturity and exposed to 5 days of high temperatures (up to 35°C) during mid grain filling. Schooner and Sloop showed similar patterns of accumulation of dry matter under control conditions (21°C/16°C, day/night temperature) and in response to high temperatures. In all varieties, the reduction in starch accumulation represented the most significant detrimental effect of high temperature and made the greatest contribution to the reduction in final grain weight. The reduction in absolute grain nitrogen (N) in heat-treated Arapiles grains represents a potentially important response under high temperature conditions. In this study, water loss did not have a decisive role in the termination of grain filling. Continued accumulation of endosperm dry matter at low moisture levels suggested that water distribution and/or components of water potential may be more important than overall water content in the cessation of grain filling. Final grain composition depended not only on the amount of endosperm storage component present in the grain but also on the contribution of the non-endosperm components (including the embryo and husk) to final grain dry weight. In some cases, changes in the contribution made by the non-endosperm components of the grain to final grain weight masked important high temperature effects on key endosperm storage components. Hot water extract (HWE) values were similar within treatments and ranged from 73% to 78%. High temperature exposure reduced HWE for all varieties. Malt b-glucan was lower in heat-treated grains than in control grains. Despite relatively high malt protein levels in all varieties, higher free amino N levels in heat-treated grains indicated a higher protein modification than in control grains.


PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11218
Author(s):  
Haoliang Yan ◽  
Chunhu Wang ◽  
Ke Liu ◽  
Xiaohai Tian

There is concern over the impact of global warming on rice production due increased heat stress, coupled with decreased relative humidity (RH). It is unknown how rice yield and quality are affected by heat stress and decreased RH during the grain filling stage. We conducted experiments in controlled growth chambers on six rice cultivars, varying in heat tolerance using 12 combinative treatments of three factors: two RH levels (75% and 85%), three temperature levels (the daily maximum temperature at 33 °C, 35 °C, and 37 °C), and two durations (8 d and 15 d after anthesis). Results showed that RH75% with temperature treatments significantly reduced grain weight, which was higher than RH85%. The same trend was also observed for both head rice rate and chalkiness. R168 was the most heat-tolerant cultivar, but it still had some differences in grain weight, head rice rate, and chalkiness between the two RH regimes. The lower RH was most detrimental at 35 °C, and to a lesser extent at 33 °C, but had a negligible effect at 37 °C. Our results provide a better understanding of temperature and RH’s interaction effects on rice quality during the grain filling stage, suggesting that RH should be considered in heat tolerance screening and identification to facilitate rice breeding and genetic improvement.


1999 ◽  
Vol 50 (3) ◽  
pp. 357 ◽  
Author(s):  
Roxana Savin ◽  
Marc E. Nicolas

In order to determine the importance of timing of short periods of high temperature and drought on grain weight and grain quality, a glasshouse experiment was carried out in which Schooner barley was exposed to short periods of heat stress (40˚C for 6 h/day for 5 consecutive days) or drought at early grain filling (10–15 days after anthesis, DAA), mid grain filling (20–25 DAA), or late grain filling (30–35 DAA). Individual grain weight was most sensitive to heat stress and drought treatments imposed early in grain filling and was less sensitive to later treatments. The reduction in grain weight was greater under heat stress (average 13%) than under drought in this study (average 6%). Starch was reduced in amount and quality, especially with early stresses during grain filling, but grain nitrogen percentage was similar between treatments.


1995 ◽  
Vol 22 (6) ◽  
pp. 927 ◽  
Author(s):  
PJ Stone ◽  
ME Nicolas

Short periods of very high temperature (> 35�C) are common in many of the world's wheat growing areas and can be a significant factor in reducing yield and quality of wheat. This study was designed to determine the stage at which grain growth is most sensitive to a short period of high temperature and to examine whether varietal differences in heat tolerance are expressed throughout the whole grain-filling period. Two varieties of wheat differing in heat tolerance (cvv. Egret and Oxley) were exposed to a short (5 days) period of very high temperature (40�C max. for 6 h each day) at 5-day intervals throughout grain filling, starting from 15 days after anthesis (DAA) and concluding at 50 DAA. Responses of grain dry matter accumulation and water content to high temperature were monitored throughout grain filling, and the results compared with controls maintained at 21/16�C day/night. Varietal differences in heat tolerance were expressed throughout the grain-filling period. Mature individual kernel mass was most sensitive to heat stress applied early in grain filling and became progressively less sensitive throughout grain filling, for both varieties. Reductions in mature kernel mass resulted primarily from reductions in duration rather than rate of grain filling.


1997 ◽  
Vol 48 (5) ◽  
pp. 625 ◽  
Author(s):  
Roxana Savin ◽  
Peter J. Stone ◽  
Marc E. Nicolas ◽  
Ian F. Wardlaw

Short periods of very high maximum temperature (>35°C) during grain filling appear to reduce grain yield and quality in barley. Tolerance of grain yield and quality to heat stress may be increased when acclimation to high temperature occurs. Two experiments were performed to test the hypothesis that a gradual (or stepped) increase to very high temperature reduces the impact of that stress on grain growth and quality of barley, compared with a sudden increase over the same temperature range. Plants experiencing either a sudden or a gradual increase did not exhibit any differences in grain weight or malting quality, but increasing the temperature in 2 steps (so that plants were exposed to 30 or 34°C for 2 h before a 40°C heat stress) appeared to have produced acclimation, since the reduction in grain weight under the 2-step treatment was about half that of either a sudden or gradual increase in temperature. Heat stress altered grain composition in various ways. The reduction in final grain weight was strongly and linearly related to the reduction in starch content. Grain β-glucan was 4·5 ± 0·5% across treatments and experiments and was significantly reduced in the glasshouse but not in the phytotron experiment. However, β-glucan degradation was similar between treatments in both experiments. Grain nitrogen concentration was very high and similar between treatments. Consequently, diastatic power was high and there was a trend towards a reduction under heat stress. Free amino nitrogen was higher under heat stress, indicating a higher protein modification than in the controls. Malt extract was significantly reduced by heat stress in the glasshouse experiment.


2017 ◽  
Vol 15 (2) ◽  
pp. 174-181
Author(s):  
Md Rasel Rana ◽  
Md Masudul Karim ◽  
Md Juiceball Hassan ◽  
Md Alamgir Hossain ◽  
Md Ashraful Haque

Grain filling determines the grain weight, a major component of grain yield in cereals. Grain filling in barley depends on current assimilation and culm reserves (mainly water-soluble carbohydrates). Nowadays barley is facing heat stress problem which is mostly responsible to reduce the yield of barley. A field experiment was conducted at the Field Lab, Department of Crop Botany, BangladeshAgriculturalUniversity, Mymensingh during November 2015 to March 2016 to study the grain filling patterns and the contributions of culm reserves to grain yield under heat stress. The experiment consisted of two factors—barley cultivars and heat stress. The heat stress was imposed by late sowing. The tillers were sampled once a week during grain filling period to determine the changes in dry weights of different parts, viz., leaves, culm with sheath, spikes, and grains; and to examine the contribution of culm reserves to grain yield. The results in the experiment revealed that the grain yield was reduced by 22-28% due to the stress. The grain yield varied from 52 to 150 g m−2 with the mean of 102 g m−2 under control while it varied from 37 to 116 g m−2 with the mean of 75 g m−2 under heat stress. Among the cultivars studied BARI Barley5, BARI Barley2 and BARI Barley1, seemed as high yielders while BARI Barley3, BARI Barley4, BARI Barley6 as the low yielders under heat stress treatment. The reduction in grain yield was attributable mainly to lighter grain weight due to the stress. Heat stress drastically reduced the grain filling duration by 45–50%. However, the stress increased the grain filling rate by 6–53%. The amount of reserves remobilized to grain varied among the cultivars ranging from 4.8 to 12.77 mg spike−1 in control and from 1.73 to 6.25 mg spike−1 in stressed plants. The stressed barley plants exhibited lower accumulation of reserves in culm but they showed almost its complete remobilization to the grain. The contribution of culm reserves to grain yield varied from 1.13 to 19.52%, and 1.09 to 2.11% in control and in stressed plants, respectively. In conclusion, culm reserve is the important attributes in grain yield in Bangladeshi barley cultivars but the contribution remains almost unaffected due the post-anthesis heat stress.J. Bangladesh Agril. Univ. 15(2): 174-181, December 2017


2002 ◽  
Vol 53 (11) ◽  
pp. 1219 ◽  
Author(s):  
Valeria S. Passarella ◽  
Roxana Savin ◽  
Gustavo A. Slafer

High temperature is usually one of the most important stresses during grain filling affecting both yield and quality in barley crops. In the present study, an attempt was made to assess in the field the effects of short periods of high temperature, using transparent boxes covering only the spikes, with thermostatically controlled electric resistance for increasing the temperature. Treatments consisted of 2 malting cultivars and 5 heat treatments of high temperatures (8�C above the environmental temperature for 6 h/day for 5 consecutive days) over different periods during grain filling. Final grain weight was reduced by 2–14%, depending on the timing of heat stress and the genotype. There was a significant increase in grain nitrogen percentage in both cultivars, and grain β-glucans decreased with high temperatures in Logan and were unchanged in Beka. The resulting malt extract was reduced with exposure to high temperatures, depending on the cultivar, implying that even mild heat stress may change malting performance.


Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 687
Author(s):  
Chan Seop Ko ◽  
Jin-Baek Kim ◽  
Min Jeong Hong ◽  
Yong Weon Seo

High-temperature stress during the grain filling stage has a deleterious effect on grain yield and end-use quality. Plants undergo various transcriptional events of protein complexity as defensive responses to various stressors. The “Keumgang” wheat cultivar was subjected to high-temperature stress for 6 and 10 days beginning 9 days after anthesis, then two-dimensional gel electrophoresis (2DE) and peptide analyses were performed. Spots showing decreased contents in stressed plants were shown to have strong similarities with a high-molecular glutenin gene, TraesCS1D02G317301 (TaHMW1D). QRT-PCR results confirmed that TaHMW1D was expressed in its full form and in the form of four different transcript variants. These events always occurred between repetitive regions at specific deletion sites (5′-CAA (Glutamine) GG/TG (Glycine) or (Valine)-3′, 5′-GGG (Glycine) CAA (Glutamine) -3′) in an exonic region. Heat stress led to a significant increase in the expression of the transcript variants. This was most evident in the distal parts of the spike. Considering the importance of high-molecular weight glutenin subunits of seed storage proteins, stressed plants might choose shorter polypeptides while retaining glutenin function, thus maintaining the expression of glutenin motifs and conserved sites.


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