Tiller development in salt-stressed wheat.
Maas E.V. | Lesch S.M. | Francois L.E. | Grieve C.M.
Wheat (Triticum aestivum L. emend. Thell.) grain yields are highly dependent upon the number of spike-bearing tillers produced per plant. Salinity, drought, and other environmental stresses can greatly affect the development and viability of tillers. We determined the effects of soil salinity on the occurrence and rate of tiller development and the incidence of tiller abortion in spring wheat cultivars, Anza and Yecora Rojo. Plants were grown in Pachappa fine sandy loam soil (mixed, thermic, Mollic Haploxeralf) in outdoor lysimeters. Three salinity treatments were imposed by irrigating with waters containing equal weights of NaCl and CaCl2 (electrical conductivities of approximately or equal to 1, 12, or 18 dS m-1). Salinity significantly decreased the number of primary and secondary tillers in both cultivars. Soil water salinities greater than or equal 7.5 dS m-1 (mean electrical conductivity of the soil water in the rootzone during tiller development, kappa SW) etiminated most of the secondary tillers and greatly reduced the number of T0, T3, and T4 tillers. However, the percentage of tillers producing spikes actually increased at kappa SW up to 8 dS m-1. Higher salinities reduced the percentage of tillers with spikes, but not as much as the reduction in tillers. Tiller and spike production per plant decreased about 0.13 to 0.15 organs for each unit increase in kappa SW. Of all the potential tillers these cultivars can produce, the primary tillers on Leaves 1 and 2 (i.e., T1 and T2) were the least susceptible to salt stress, partly because they emerged before salinity builds up during the irrigation season. Adjusting planting densities to increase the number of anticipated spike-bearing culms per unit area could help to maintain yields on salt-affected soils.
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