Breaking Uniculm Growth Habit of Spring Cereals at High Latitudes by Crop Management. II. Tillering, Grain yield and Yield Components

Abstract

Long days at high latitudes inhibit tillering of cereals and hence seeding rates of 500–700 seeds m−2 are commonly used for spring wheat, barley and oats in Finland. Costs could be reduced by using a lower seeding rate in combination with crop management to produce more head‐bearing tillers m−2. This study was designed to assess possibilities of breaking the uniculm growth habit of spring cereals by (1) lowering the seeding rate from 600 to 300 seeds m−2 and (2) manipulating tiller growth with early mechanical treatments to the crop (rolling, cutting) or chemical applications (foliar urea, CCC and GA). A low seeding rate and early application of foliar CCC at high latitudes, under good moisture conditions prior to heading, promoted 20% more head‐bearing tillers and 6% higher grain yield than standard management practices. However, cultivars differed in their response to CCC. The advantageous effects of CCC at a low seeding rate were attributed to increase, over the controls, in contribution of head‐bearing tillers to grain yield in wheat (cultivar Heta), but more grains per head in oats (cultivar Veli). Varietal recommendations for use of low seeding rate in combination with early CCC spraying should be examined further.

Plant Growth Regulator Effects on Spring Cereal Root and Shoot Growth

“…Increased tiller number in the first trial did not increase in parallel with tiller biomass, number of spike‐bearing tillers, and tiller grain yield (Table 5). This was also the case in the studies of Waddington and Cartwright (1986), Woodward and Marshall (1987), Foster et al (1991), and Peltonen and Peltonen‐Sainio (1997)…”

“…Enhanced tillering may result in higher yield potential due to more spike‐bearing tillers per main shoot. Treatments with PGRs have increased tillering and number of spikes per unit area in cereals (Humbries et al, 1965; Cartwright and Waddington, 1982; Waddington and Cartwright, 1986; Ramos et al, 1989; Ma and Smith, 1991; Peltonen and Peltonen‐Sainio, 1997), though this did not invariably have a positive effect on grain yield. In our trials, ethephon and TE treatments were followed by slight increases (6–30%) in tiller number compared with the control when measured 14 DAT (Tables 2 and 4).…”

“…Applications of PGRs have modified tiller number, especially when applied as a seed treatment or during early growth stages (Cartwright and Waddington, 1982; Hutley‐Bull and Schwabe, 1982; Koranteg and Matthews, 1982; Waddington and Cartwright, 1986; Woodward and Marshall, 1987, 1988; Ma and Smith, 1991). Ethephon, CCC, and mepiquat chloride, alone and in mixtures, stimulated tillering and occasionally increased the number of spike‐bearing tillers (Cartwright and Waddington, 1982; Koranteg and Matthews, 1982; Waddington and Cartwright, 1986; Naylor and Saleh, 1987; Woodward and Marshall, 1987, 1988; Craufurd and Cartwright, 1989; Ramos et al, 1989; Ma and Smith, 1991; Moes and Stobbe, 1991; Peltonen and Peltonen‐Sainio, 1997). In some experiments, this resulted in higher grain yield (Cartwright and Waddington, 1982; Waddington and Cartwright, 1986; Ramos et al, 1989; Peltonen and Peltonen‐Sainio, 1997), whereas in others it did not (Woodward and Marshall, 1988; Foster et al, 1991; Ma and Smith, 1991; Moes and Stobbe, 1991).…”

“…Ethephon, CCC, and mepiquat chloride, alone and in mixtures, stimulated tillering and occasionally increased the number of spike‐bearing tillers (Cartwright and Waddington, 1982; Koranteg and Matthews, 1982; Waddington and Cartwright, 1986; Naylor and Saleh, 1987; Woodward and Marshall, 1987, 1988; Craufurd and Cartwright, 1989; Ramos et al, 1989; Ma and Smith, 1991; Moes and Stobbe, 1991; Peltonen and Peltonen‐Sainio, 1997). In some experiments, this resulted in higher grain yield (Cartwright and Waddington, 1982; Waddington and Cartwright, 1986; Ramos et al, 1989; Peltonen and Peltonen‐Sainio, 1997), whereas in others it did not (Woodward and Marshall, 1988; Foster et al, 1991; Ma and Smith, 1991; Moes and Stobbe, 1991). Increase in tiller formation may be due to changes in responsiveness to day length (Hutley‐Bull and Schwabe, 1982; Craufurd and Cartwright, 1989), inhibition of biosynthesis and transport of apical dominance initiating auxins (Morgan and Gausman, 1966; Lyon, 1970; Evans, 1984), or changes in assimilate and nutrient availability (Woodward and Marshall, 1987, 1988).…”

Chlormequat chloride and ethephon affect growth and yield formation of conventional, naked and dwarf oat

“…Oat might, however, represent even greater potential for such manipulation, because the inflorescence rather than an ear is likely to be more responsive to environmental factors and crop management that favour yield formation (Peltonen-Sainio 1999). There have been few experiments with PGR-treated oat (Peltonen-Sainio and Peltonen 1997, Pietola et al 1999, Rajala and Peltonen-Sainio 2000, but some tentative evidence exists for oat responding to PGR treatments. For example, oat treated with CCC at two to three tiller stage (growth stage, GS22-23, Zadoks et al 1974) had more grains per panicle than control plants (Peltonen and Peltonen-Sainio 1997).…”