Green Area Duration during the Grain Filling Period of an Argentine Wheat Cultivar as Influenced by Sowing Date, Temperature and Sink Strength

Abstract

The effects of sowing date, air temperature during the grain filling period, sink‐strength, and then‐interactions on the wheat green area (leaves, leaf sheaths and peduncles) duration from anthesis to total senescence were determined under field conditions at Buenos Aires (Argentina). The individual grain weight was determined as an average of either all grains or basal grains of the spikelets 7 and 8 through the treatments. The delayed sowing date reduced the period of leaf senescence when it was regarded as calendar time between anthesis to maturity, but it did not affect that period regarded as thermal time. Similarly, the increased temperature has also increased the rate of senescence. On the other hand, the sink strength did not affect the green area duration; since neither the rate nor the period of senescence was altered. Similarly, both sowing date and mean temperature decreased the individual grain weight, but the sink strength did not affected the weight of the basal grains, which could be interpreted as the effects of the other two factors were independent to the availability of assimilates per grain. The effect of increased grain filling temperature on reducing grain weight did not operate via reducing the availability of assimilates although it also reduced the total grain area duration. We observed that the increased temperature decreased the individual grain weight of the basal grains at any source sink ratio.

Understanding grain yield responses to source–sink ratios during grain filling in wheat and barley under contrasting environments

“…Acreche and Slafer, 2011;Serrago et al, 2011) or if they affect grain weight potential (e.g. Slafer and Miralles, 1992;Calderini and Reynolds, 2000). For example, leaf diseases (Serrago et al, 2011) or lodging (Acreche and Slafer, 2011) would only produce a source-limited grain growth when they are very severe, implying that mild stresses would not affect grain size.…”

Yield response to heat stress as affected by nitrogen availability in maize

“…For instance, at high temperature grains could hardly grow even when the concentration of soluble sugars was high (Jones et al, 1981). Thus high temperature effect on grain size cannot be reversed, nor diminished, by increasing the source-sink ratio (Slafer and Miralles, 1992). Another direct effect of heat stress on grain weight might be through increasing the rate of water loss from the grain during the first half of the effective grain filling period (Rattalino Edreira et al, 2014).…”

Post-anthesis warm nights reduce grain weight in field-grown wheat and barley

“…Base temperature of 8.2 • C for wheat (Slafer and Savin, 1991) and 7.5 • C for barley (Gualano and Benech-Arnold, 2009) were assumed. direct effect on grain development and/or is partially mediated by effects on the canopy as source of assimilates (Wardlaw et al, 1980;Slafer and Miralles, 1992), as dark respiration is known to increase exponentially with temperature (Penning de Vries et al, 1979). Interception of green leaf area and availability and consumption (i.e.…”

“…Assimilates supply and contributions from reserves (non-structural carbohydrates previously stored in stems) are frequently reported to be enough to deal with sink demand during grain filling (Borrás et al, 2004;Dreccer et al, 2009;Serrago et al, 2013). However, frequent adverse conditions such as biotic constraints (Bingham et al, 2009;Serrago et al, 2011) or higher temperatures (Slafer and Miralles, 1992;Savin et al, 1997) can modify source-sink ratio generating a source limitation that reduces the final grain weight (Fischer and Maurer, 1976;Serrago and Miralles, 2014) and, in turn, temperate cereals grain yield (Chowdhury and Wardlaw, 1978;Wardlaw et al, 1980). Industry penalties due to the down-grade of commercial quality (Rattey et al, 2009) or poor seedling establishment in stressed environments (Grieve and Francois, 1992) can also be linked with smaller grains.…”