Peer review

To clarify the influence of post‐jointing drought on the ear‐bearing and seed‐setting characteristics of the main stem and tillers of winter wheat (Triticum aestivum L.), a pot experiment was conducted with cultivars “Shannong 29” (SN29) and “Heng 0628” (H0628), and five water regimes: mild drought (WR1) and severe drought (WR2) for 0–5 days after jointing, mild drought (WR3) and severe drought (WR4) for 0–10 days after jointing and adequate water supply as a control (CK). The present study focused on primary tillers (appear in the axils of main stem leaves: T1, T2, T3, T4, etc.), as well as on secondary tillers (appear from the bud in the axil of the prophyll: T10 and T20; appear in the axil of the first leaf of the primary tiller T1: T11). The yield components of tillers showed a downward trend with increasing tiller position and drought degree and duration, and the kernels per spike, single kernels weight and grain yield per spike of tillers T2, T3, T10 and T4 decreased more than those of the other tillers. These outcomes may be related to the spike developmental stages at the time of the drought period. Severe drought during the period from when the stamen primordium is first present (Waddington’s stage 4) to when the carpel extends around the three sides of the ovule (Waddington’s stage 5) significantly decreased the seed set of tillers, but short‐term (5 days) mild drought during this period and even a short‐term severe drought before Waddington’s stage 4 had little effect on the seed set of tillers. The ear‐bearing capacity of tillers was determined not only by the spike developmental stage, but also by the gap from the main stem and the competition of nutrition and space between tillers. Although the ear‐bearing rate of tillers T3 and T10 decreased rapidly after the short‐term mild drought, the increase in the ear‐bearing rate of tillers T20 and T11 effectively compensated for the loss of the number of spikes per plant. Therefore, the short‐term mild drought at the jointing stage had no significant effect on the grain yield of the two cultivars. The tillers T2, T3, T10 and T4 were sensitive to soil moisture in the jointing stage and had high plasticity. During this period, if timely irrigation improves soil moisture, it is expected to increase the ear‐bearing rate and seed set of these tillers, thereby increasing grain yield.

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