Interpretation of grain quality results from wheat variety trials with reference to high temperature stress

Abstract

Grain quality results for variety trials extending over 27 years (3 sites and 5 varieties) were compared with the temperature profiles during the grain filling period (56 days prior to harvest) to determine the effects on quality of high temperatures (>35�C) during this period of growth. Heat stress episodes have been frequent at two (Narrabri, N.S.W., and Turretfield, S.A.) of the three sites studied; spring temperatures were more moderate at the third site, Wongan Hills, W.A. There were highly significant (P< 0.01) correlations of heat stress (as hours above 35�C, during grain filling) with protein content (positive) and with grain yields (negative) at Narrabri for all varieties. In many combinations of site and variety, heat stress correlated negatively with loaf volume, and with dough strength (as Rmax, resistance to stretching with the Extensograph). Heat stress episodes in the Narrabri (N.S.W.) region in 1981 and 1982 gave further opportunity to examine these relationships. Results showed very clearly that high temperatures late in grain filling were associated with weaker dough properties (lower Rmax) in the resulting grain. These trends may form the basis of a predictive system by which to estimate crop quality and to interpret the results of variety trials.

Influência das temperaturas mínima e máxima em características de qualidade industrial e em rendimentos de grãos de trigo

“…Depreendese desse fato que, no estádio inicial de enchimento de grãos, as plantas sejam mais sensíveis ao estresse pelo calor que em estádios mais avançados, nos quais, conforme descrito anteriormente, a temperatura elevada correlacionou-se positivamente com o peso de mil grãos e com o rendimento de grãos. Ao contrário dos resultados obtidos nesse trabalho, dados de literatura indicaram que a influência de elevada temperatura (acima de 30ºC) afetou negativamente a força de glúten [8,9,26,30].…”

Differential responses of bread wheat characters to high temperature

“…Other factors such as leaf senescence (A1- Khatib & Paulsen, 1984;Kuroyanagi & Paulsen, 1985) and adverse physiological and biochemical changes (Berry & Bjorkman, 1980;A1-Khatib & Paulsen, 1984;Blum, 1986;Jenner, 1991aJenner, , 1991b) also contribute to low production under high temperatures. Recent studies (Blumenthal et al, 1991a(Blumenthal et al, , 1991bRandall & Moss, 1990) indicated that high temperature during the grain-filling stage had adverse effects on breadmaking quality.…”

II. Heat stress in Triticum: kinetics of Cu and Zn accumulation

“…The effects of heat stress after anthesis can integrate plant responses to periods with moderate high temperatures (25/32ºC) (Chinoy, 1947;Wardlaw et al, 1989) and plant behaviors to short periods with high temperatures (higher than 32ºC) (Randall and Moss, 1990;Blumenthal et al, 1991). In a previous study, our research group, working on heat stress after anthesis (Maçãs et al, 2000;Dias et al, 2008, found that Triticum aestivum L. genotype Sever is more tolerant than the genotype Golia and that Triticum turgidum subsp.…”