Effect of Timing of Heat Stress During Grain Filling on Two Wheat Varieties Differing in Heat Tolerance. I. Grain Growth

1995 ◽  
Vol 22 (6) ◽  
pp. 927 ◽  
Author(s):  
PJ Stone ◽  
ME Nicolas
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Grain Growth ◽  
Heat Tolerance ◽  
Grain Filling ◽  
Dry Matter Accumulation ◽  
Varietal Differences ◽  
Short Period ◽  
Grain Filling Period ◽  
Very High

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.

Effect of Timing of Heat Stress During Grain Filling on Two Wheat Varieties Differing in Heat Tolerance. II. Fractional Protein Accumulation

1996 ◽  
Vol 23 (6) ◽  
pp. 739 ◽  
Author(s):  
PJ Stone ◽  
ME Nicolas
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Grain Growth ◽  
Heat Tolerance ◽  
Grain Filling ◽  
Size Exclusion ◽  
Protein Accumulation ◽  
Wheat Varieties ◽  
Grain Filling Period ◽  
Very High

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.

Grain growth and malting quality of barley. 1. Effects of heat stress and moderately high temperature

1997 ◽  
Vol 48 (5) ◽  
pp. 615 ◽  
Author(s):  
Roxana Savin ◽  
Peter J. Stone ◽  
Marc E. Nicolas ◽  
Ian F. Wardlaw
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Grain Growth ◽  
High Temperatures ◽  
Grain Filling ◽  
Grain Weight ◽  
Malting Quality ◽  
Very High ◽  
Moderately High Temperature

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.

The effect of duration of heat stress during grain filling on two wheat varieties differing in heat tolerance: grain growth and fractional protein accumulation

1998 ◽  
Vol 25 (1) ◽  
pp. 13 ◽  
Author(s):  
P.J. Stone ◽  
M.E. Nicolas
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
High Temperature ◽  
Heat Tolerance ◽  
Grain Filling ◽  
Protein Accumulation ◽  
Tolerant Variety ◽  
Heat Tolerant ◽  
Very High ◽  
Individual Kernel

Two varieties of wheat differing in heat tolerance were exposed to very high temperature (40/19°C day/night) for periods of 1–10 days duration. Responses of grain dry matter, water and fractional protein accumulation to high temperature were monitored throughout grain filling in the heat- sensitive variety, and at maturity only in the heat-tolerant variety. Results are compared with controls maintained at 21/16°C day/night. As little as 1 day of heat treatment reduced kernel mass by 14% in the heat-sensitive variety (Oxley), but by only 5% in the heat-tolerant variety (Egret). In both varieties, the reduction of individual kernel mass due to high temperature increased linearly with increased duration of heat treatment, such that after the first day of heat stress, each additional day of treatment reduced mature individual kernel mass by a further 1.6%. For a given duration of heat treatment, the difference in response of the two varieties was constant (9%), indicating that the varietal difference in heat tolerance was maintained for both brief and extended periods of very high temperature. Responses of grain water content and fractional protein accumulation to duration of heat stress are discussed.

Comparison of sudden heat stress with gradual exposure to high temperature during grain filling in two wheat varieties differing in heat tolerance. II. Fractional protein accumulation

1998 ◽  
Vol 25 (1) ◽  
pp. 1 ◽  
Author(s):  
P.J. Stone ◽  
M.E. Nicolas
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Heat Tolerance ◽  
Temperature Increase ◽  
High Performance ◽  
Protein Composition ◽  
Grain Filling ◽  
Size Exclusion ◽  
Protein Accumulation ◽  
Wheat Varieties

Two varieties of wheat differing in heat tolerance (cvv. Egret and Oxley, tolerant and sensitive, respectively) were exposed to either a sudden or gradual (6°C h-1) increase from 20 to 40°C to determine if the rate of temperature increase used in controlled-environment studies (1) alters the accumulation of functionally important proteins during grain-filling, and (2) affects the ability to discriminate between heat tolerant and sensitive varieties of wheat. After heat treatment, grain samples were taken throughout grain growth and analysed for protein content and composition. Wheat proteins were separated and quantified as albumin/globulin, monomer, SDS-soluble polymer and SDS-insoluble polymer using size-exclusion high-performance liquid chromatography. The rate of temperature increase exerted a significant influence on the accumulation of total wheat protein and its fractions, and protein fractions differed in their responses to the suddenness of heat stress. The acclimation to heat stress afforded by a gradual increase to high temperature can mitigate the effects of heat stress on fractional protein accumulation, and consequently grain protein composition at maturity. Furthermore, the ability of wheat to acclimate to high temperature varies between genotypes, and this needs to be taken into account when selecting for heat tolerance.

Effect of timing of heat stress during grain filling in two wheat varieties under moderate and very high temperature

2015 ◽  
Vol 75 (1) ◽  
pp. 121
Author(s):  
W. F. Song ◽  
L. J. Zhao ◽  
X. M. Zhang ◽  
Y. M. Zhang ◽  
J. L. Li ◽  
...  
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Grain Filling ◽  
Wheat Varieties ◽  
Very High

Grain growth and malting quality of barley. 2. Effects of temperature regime before heat stress

1997 ◽  
Vol 48 (5) ◽  
pp. 625 ◽  
Author(s):  
Roxana Savin ◽  
Peter J. Stone ◽  
Marc E. Nicolas ◽  
Ian F. Wardlaw
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Grain Growth ◽  
Gradual Increase ◽  
Grain Weight ◽  
Malting Quality ◽  
Yield And Quality ◽  
Grain Yield And Quality ◽  
Very High

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.

The Influence of Recovery Temperature on the Effects of a Brief Heat Shock on Wheat. I. Grain Growth

1995 ◽  
Vol 22 (6) ◽  
pp. 945 ◽  
Author(s):  
PJ Stone ◽  
R Savin ◽  
IF Wardlaw ◽  
ME Nicolas
Keyword(s):  
High Temperature ◽  
Heat Shock ◽  
Grain Growth ◽  
High Temperatures ◽  
Wheat Yield ◽  
Grain Filling ◽  
Mature Individual ◽  
Very High ◽  
Moderately High Temperature ◽  
Individual Kernel

The responses of wheat yield to moderately high (20-32�C) and very high temperatures (> 32�C) have been studied separately in the literature, but not in combination, despite the fact that this is usually how elevated temperatures occur in the field. In this study, controlled environment conditions were used in order to examine the interaction of moderately high and very high temperatures during grain filling and their effect on wheat yield. Specifically, we wished to test the hypothesis that cooler conditions would facilitate greater recovery of grain growth following a brief exposure to very high temperature. To this end, wheat was exposed to either 21/16 or 40/16�C (day/night) from 15-19 days after anthesis and subsequently grown under one of three moderately high temperature regimes until maturity: 21/16, 27/22 or 30/25�C. For all moderately high temperature treatments, a brief 'heat shock' significantly reduced mature individual kernel mass by 17%, on average. In the absence of 'heat shock', increasing moderately high temperature progressively reduced mature individual kernel mass by ca 2.5% for each 1�C increase in average daily temperature. After a 'heat shock' event, however, there was not a progressive decline in mature individual kernel mass with increasing moderately high temperature. A short period of very high temperature applied early in grain filling therefore reduced the response of wheat to subsequent moderately high temperatures. We conclude that the reduction in yield caused by 'heat shock' is not alleviated by cool post-shock conditions.

scholarly journals The Physiological Basis of Improved Heat Tolerance in Selected Emmer-Derived Hexaploid Wheat Genotypes

2021 ◽  
Vol 12 ◽  
Author(s):  
Smi Ullah ◽  
Richard Trethowan ◽  
Helen Bramley
Keyword(s):  
Heat Stress ◽  
Heat Tolerance ◽  
Stress Responses ◽  
Selection Process ◽  
Abiotic Stress Tolerance ◽  
Grain Filling ◽  
Complex Nature ◽  
Physiological Basis ◽  
Wheat Genotypes ◽  
Short Period

Wheat is sensitive to high-temperature stress with crop development significantly impaired depending on the severity and timing of stress. Various physiological mechanisms have been identified as selection targets for heat tolerance; however, the complex nature of the trait and high genotype × temperature interaction limits the selection process. A three-tiered phenotyping strategy was used to overcome this limitation by using wheat genotypes developed from the ancient domesticated wheat, emmer (Triticum dicoccon Schrank), which was considered to have a wide variation for abiotic stress tolerance. A contrasting pair of emmer-based hexaploid lines (classified as tolerant; G1 and susceptible; G2) developed from a backcross to the same recurrent hexaploid parent was chosen based on heat stress responses in the field and was evaluated under controlled glasshouse conditions. The same pair of contrasting genotypes was also subsequently exposed to a short period of elevated temperature (4 days) at anthesis under field conditions using in-field temperature-controlled chambers. The glasshouse and field-based heat chambers produced comparable results. G1 was consistently better adapted to both extended and short periods of heat stress through slow leaf senescence under heat stress, which extended the grain filling period, increased photosynthetic capacity, increased grain filling rates, and resulted in greater kernel weight and higher yield. The use of a combination of phenotyping methods was effective in identifying heat tolerant materials and the mechanisms involved.

The Influence of Recovery Treatment on the Effects of a Brief Heat Shock on Wheat. II. Fractional Protein Accumulation During Grain Growth

1996 ◽  
Vol 23 (5) ◽  
pp. 605 ◽  
Author(s):  
PJ Stone ◽  
ME Nicolas ◽  
IF Wardlaw
Keyword(s):  
High Temperature ◽  
Grain Growth ◽  
High Performance ◽  
Protein Composition ◽  
Grain Filling ◽  
Interactive Effects ◽  
Size Exclusion ◽  
Protein Accumulation ◽  
Temperature Regimes ◽  
Very High

In this study, we have sought to identify the nature of the response to both moderately high (25-32�C) and very high (>32�C) temperatures by examining their interactive effects on the accumulation of functionally important proteins during grain-filling. In particular, we wished to determine if the deleterious effects of very high temperature could be alleviated by subsequently cool conditions. To this end, wheat cv. Oxley was exposed to either 21/16 or 40/16�C (day/night) from 15 to 19 days after anthesis and subsequently grown under one of three temperature regimes until maturity: 21/16 (control), 27/22 or 30/25�C. Grain samples were taken throughout grain growth and analysed for protein content and composition. Wheat proteins were separated and quantified as albumin,globulin, monomer, SDS-soluble polymer and SDS-insoluble polymer using size-exclusion high-performance liquid chromatography. The various protein fractions responded differentially and usually additively to moderately high and very high temperatures during grain-filling. Cool post-shock conditions did not alleviate the effects of very high temperature on grain protein composition. Heat treatments reduced polymer:monomer ratio because the accumulation of monomer was reduced less than that of polymer.

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
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Grain Growth ◽  
Grain Filling ◽  
Grain Weight ◽  
Maximum Temperature ◽  
Starch Accumulation ◽  
Nitrogen Accumulation ◽  
Barley Cultivars ◽  
High Temperature Maximum

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.

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