Abstract
ABSTRACT Although source–sink relationships in wheat are well studied, the performance of tillers as transient sinks is still unclear, especially under stress conditions. Thus, this work aimed to study the yield relationships of wheat stems in contrasting genotypes as affected by tiller treatment under stress conditions. Two experiments were conducted under greenhouse conditions using BRS Guamirim (high tillering) and BRS Parrudo (low tillering) wheat cultivars. Four tillering treatments were applied on late tillers in the first growing season (2016) and three in the second (2017): (i) free-tillering, (ii) detillering, (iii) physical suppression (only in the first season) and (iv) “spikes removal”. The main stem and the first four emitted tillers were considered as primary tillers. Plants were submitted to drought (2016) and defoliation stress (2017) at preanthesis. Intraspecific competition among tillers increased under drought stress conditions and decreased the plant performance. Nonproductive late tillers do not improve the performance of primary tillers of wheat plants under drought stress, mainly in high-tillering cultivars. The reduction on the thousand grain weight of only ‘Parrudo’ detillered plants indicates that assimilate remobilization from late tillers to primary tillers and main stem seems to be more effective in low-tillering cultivars.
Highlights
Comparison among wheat cultivars with contrasting tillering has been addressed under several conditions, such as sowing dates and densities, plant nutrition and environmental stresses (Duggan et al 2005a, b; Ruan et al 2012; Mitchell et al 2013; Guo and Schnurbusch 2015; Hendriks et al 2016; Houshmandfar et al 2019)
Nonproductive late tillers do not improve the performance of primary tillers of wheat plants under drought stress, mainly in high-tillering cultivars
The reduction on the thousand grain weight of only ‘Parrudo’ detillered plants indicates that assimilate remobilization from late tillers to primary tillers and main stem seems to be more effective in low-tillering cultivars
Summary
Comparison among wheat cultivars with contrasting tillering has been addressed under several conditions, such as sowing dates and densities, plant nutrition and environmental stresses (Duggan et al 2005a, b; Ruan et al 2012; Mitchell et al 2013; Guo and Schnurbusch 2015; Hendriks et al 2016; Houshmandfar et al 2019). Despite all these studies, it remains difficult to dissect the interactions between main stem and tillers regarding source–sink relationships, mainly under stress conditions. To act as a transient sink of assimilates, senescent tillers would have to keep these vascular connections with the other stems of the plant (tillers or main stem) until the grain filling stage
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