Productive Tiller Development In Wheat.

Recent research has shown that over 80% of the yield in a wheat crop comes from tillers that produce 30 kernels or more per spike.  This work indicates that increasing yield could be achieved by maximizing the number of tillers that develop large numbers of kernels.  This study found that the tillers most likely to produce large numbers of kernels were formed in the late fall from early November through late December.  Unfortunately, these productive tillers were also more susceptible to freezing temperatures in the spring and were adversely affected by the lack of N available during the period from late February to early April.  This is part of the reason why planting more seed is not an effective way of increasing yield.  Tillers that come from higher seeding rates are even more prone to freeze damage or to loss due to lack of N during the spring.  Similarly, yield in no-till fields is impacted because the development of tillers in November and early December is affected by residue that either reduces the amount of light and heat available to small plants or competes with small wheat plants for N during this critical period.  The goal of this project is to identify environmental conditions and management practices that result in tillers that produce maximum numbers of kernels per spike. Key objectives are to: 1) determine the period when productive tillers with large seed numbers are developed during the growth cycle of the wheat plant, 2) identify environmental factors that contribute to tillers with large spikes, and 3) identify management practices that promote strong tillers or that prevent productive tillers from being lost due to freeze or other types of injury.