Tillage, Seed Size, and Seed Density Effects on Performance of Soft White Winter Wheat

Abstract

Conservation tillage systems, which leave residues on or near the soil surface, can suppress soft white winter wheat (Triticum aestivum L.) emergence, early development of seedlings, and grain yield. This field study evaluated effects of tillage, seed size, and seed density on the above parameters. Commercially processed, untreated ‘Stephens’ winter wheat grains, separated into size‐density combinations of large‐dense, largelight, small‐dense, small‐light, and unsorted, were seeded into tilled and nontilled soil in the fall of 1990 and 1991. In 1990, when seed zone soil moisture was adequate, tillage significantly decreased seminal root intercepts at 3 cm (16%) and 5 cm (24%) below the seed. There was no significant effect of seed size‐density. When seed zone soil moisture was marginal in 1991, tillage significantly increased emergence (15%), number of main stem leaves (11%), seminal roots (4%), root intercepts (3 and 5 cm > 100%), straw yield (17%), and grain yield (12%). The only significant effect of seed size and density on aboveground parameters was on main stem leaf number, seedling weight, and number of heads. Small‐light seed had significantly more 3‐cm (53%) and 5‐cm (39%) root intercepts and 26% fewer disease‐pruned roots than other size‐density treatments. Seed size and density did not significantly affect grain yield in either year. Therefore, there is not sufficient justification to change the current seed processing procedure by use of a gravity table.

Effects of No‐Till on Yields as Influenced by Crop and Environmental Factors

“…Differences between no‐till and tillage sorghum (SORG) and wheat (WHEAT) yields were larger than the difference between no‐till and tillage corn yields with all other factors being equal. Increased soil moisture, or soil water content, from the residues left in the field was by far the most common explanation for increased no‐till sorghum and wheat yields from the studies used in this analysis (Dao and Nguyen, 1989; Douglas et al, 1994; Norwood, 1992; Tarkalson et al, 2006; Wiese et al, 1998; Winter and Unger, 2001). Even though the coefficient for oat was negative and significant, it is difficult to draw any conclusions about differences in yields for OAT without including the OAT × LOGYR and OAT × RAIN coefficients because the data were from a single experiment.…”

Switchgrass Seedling Development as Affected by Seed Size

“…Early in the growing season, corn plant height was slightly less for small-seed vs. large-seed plants (Hunter and Kannenberg, 1972). In wheat, small and large seed sizes produced plants with similar early season growth and grain yield (Douglas et al, 1994).…”

“…Most investigations evaluating seedling growth in perennial grasses have been conducted in growth chambers or greenhouses, with seedling growth characteristics measured over a short period of time during the seedling emergence phase. Field studies with annual grain crops such as corn (Zea mays L.) and wheat (Triticum aestivum L.) have shown no relationship between seed size and grain yield (Graven and Carter, 1990;Hunter and Kannenberg, 1972;Douglas et al, 1994). Little research has been conducted relating seed size to the adventitious root development phase of grass seedling establishment.…”

Performance of wheat cultivars sown at different seeding rates under drought-stress conditions

“…Optimum plant densities vary greatly between areas according to climatic conditions, soil, sowing time, and cultivars. Consequently, there is value in defining relationships between density and wheat yield to establish optimum seeding rates for various regions (Campbell et al 1991;Douglas et al 1994;Qi-Yuan et al 1994;Anderson and Barclay 1991). Research shows a variation in the responses of different wheat cultivars to density (Couvreur et al 1999;Wiersma 2002).…”