Effect of timing of heat stress during grain filling in two wheat varieties under moderate and very high temperature
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Abstract
In order to examine the effect of short periods heat stress on grain growth, two cultivars (Longmai26 and Longmai30) were grown in pots at two different diurnal temperatures (32/22°C; 25/15°C) in climate-controlled growth cabinets
and exposed to a 5-day heat stress (38/22°C) at 5-day intervals throughout grain filling after anthesis.The results indicated that long periods of moderate high temperature (>30°C) have higher effect than short periods of heat stress
(5 days with maximum 38°C for 6h each day). However, plants grown at the moderate temperature (25/15°C) showed a greater response to a short period of heat stress than plants grown at the high temperature (32/22°C). At elevated
temperatures, the change in the rate of grain filling is smaller than duration of grain filling.The high grain-filling rate and high potential grain weight should be used as a criterion in selecting for high temperature tolerance in wheat.