Delayed nitrogen application and late tiller production in wheat grown under greenhouse conditions
2000
Adjetey, J.A. (National University of Lesotho, Mokhotlong (Lesotho). Department of Crop Science) | Campbell, L.C. (University of Sydney , Sydney (Australia). School of Crop Sciences)
Delaying application of N to wheat until the time of heading or beyond increased grain protein content rather than grain yield. In a previous unreported glasshouse experiment by the current authors, application of high amounts of N (700 mg N pot-l of 2 I volume) at the time of anthesis stimulated the production of fresh tillers in the post-anthesis period in spring wheat. This phenomenon is not of common occurrence. The current study examined the levels of tissue N concentration in the post-anthesis period that triggered late tiller productionit also examined the grain production potential of these late tillers, by providing them with adequate moisture under glasshouse conditions even after early season tillers had reached ma~ty .In two treatents in the glasshouse, N was applied at 250 and 700 mg pot at sowmg. In SIX other treatments, 250 mg N pot- was applied at sowing and a second dose of 450 mg N pot-l was applied at 0,5, 10, 15,20 and 30 days after anthesis. Stimulation of late tiller production occurred when N was applied at any time during the f1fSt 30 days after anthesis. However, the contribution of late tillers to grain yield plant-l declined as the time of N application was delayed post-anthesis. Also, the leaf N concentration at which the production of late tillers was stimulated varied according to the time of N application in the post-anthesis period. Of all the split treatments, application of N at anthesis produced the largest grain yield per plant due to a 36% contribution from late tillers. We conclude that late tillers can make a useful contribution to grain yield plant-l under glasshouse conditions. However, the long time lag between the maturity of early and late season tillers may pose practical difficulties to harvesting, even if the same phenomenon were to be duplicated under field conditions.
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