Measuring Tiller Development and Mortality in Winter Wheat under Field Conditions

Abstract

Core Ideas Seeding rate is important for measuring phyllochron interval and maximum number leaf. As seeding rate increases, phyllochron interval increases; as seeding rate increases, maximum leaf number decreases. High seeding rate led to an increase in tiller production per m2 compared with low seeding rate. Neither seeding rate nor N application timing increased tiller viability. Vegetative growth in the form of tillers is crucial in development of wheat (Triticum aestivum L). To better understand wheat development and tiller initiation, a study was conducted using two seeding rates (193 vs. 676 m−2) and two N application timings (single vs. split). Using a detailed marking technique to track leaf and tiller growth, tillers plant−1, rate of leaf appearance tiller−1, phyllochron interval (PI), accumulated heat units, and maximum leaf number (MLN) were measured. Although the timing of tiller initiation did not differ among the two seeding rates, results showed that at the low seeding rate (LSR) the frequency of leaf appearance on each tiller was increased, resulting in tillers having more leaves at decimal growth stage (DGS) 30. At the high seeding rate (HSR), leaf appearance among tillers was reduced, resulting in only fall tillers having enough leaf area to sustain growth from DGS 30 to harvest. The MLN was significantly greater at the LSR compared with the HSR. The MLN for the main stem was greater than those found on Tiller 1, and MLN for Tiller 1 was greater than those found on Tiller 2. There were no significant interactions or main effects involving the timing of N. It is difficult to determine the role that N application timing has on tiller and leaf development since there was not a consistent effect of N timing on PI and no effects of N timing on MLN.