Growth Regulator Effects on Aboveground Dry Matter Partitioning during Grain Fill of Spring Barley
- B. L. Ma and
- Donald L. Smith
It is not clear whether alteration in grain yield due to application of plant growth regulators (PGRs) to cereal crops is caused by altered dry matter accumulation, changes in partitioning of dry matter into grain, or both. A 3-yr field study was conducted using two widely grown spring barley (Hordeum vulgare L.) cultivars, Cadette and Leger, to evaluate the effects of chlormequat (CCC) (2-chloroethyl-N,N,N- trimethylammonium chloride) or ethephon (2-chloroethyl phosphonic acid) on dry matter production and partitioning among plant parts during grain fill. The growth regulators were applied at three stages of crop development. The experiments were conducted on Bearbrook clay soil (fine, mixed, nonacid, Mesic Humaquept) at McGill University, Canada, from 1987 to 1989. Treatments consisted of application of CCC (1.2 kg a.i. ha−1) or ethephon (0.48 kg a.i. ha−1) at Zadoks growth stage (ZGS) 13, 30 and 39. Ethephon application at ZGS enhanced dry matter accumulation in the nongrain plant parts (chaff, culms, leaf blades, and leaf sheaths) in both 1988 and 1989, and decreased grain mass per spike (number of grains per spike and 1000- grain weight) in 1989. This resulted in a yield reduction in that year. In 1988, an increased grain mass per spike with ethephon resulted in improved grain yield. For Cadette, CCC treatment also increased dry matter accumulation in leaf blades, leaf sheaths, and chaff in 1988. Grain yield per square meter was also increased by a ZGS-13 application in that year. In general, this work revealed that PGR application does not increase total dry matter accumulation on a per-shoot basis, but does affect dry matter partitioning patterns, leading to alterations in grain yield that may be positive or negative depending on the conditions during a given crop year.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 1992.