Grazing early sown wheat crops has proved a winner in terms of yield in FAR's 20 by 2020 research programme this year. Project Manager Rob Craigie says grazing is a way of utilising the extra autumn growth from the early planting as well as providing some disease and lodging control.
"Work at the 20 by 2020 site this season has shown that grain yield of 16.7 t/ha was achieved from a treatment that was mown in May and again in August yielding 2,500 kg of dry matter. The mowing treatment did not receive a PGR and did not lodge in a trial that had severe lodging. Research this season will investigate if it is advantageous to cut the crop higher leaving a greater residual biomass and will also compare defoliating the crop once or twice."
The 20 by 2020 programme has now completed four seasons. In this research the yields of winter wheat crops sown in February and March have been compared to more traditional April plantings.
Results to date have shown that crops planted in late March can be more productive than April sowings, but that earlier March and February planting results in excessive growth, which “chokes” the crop causing a period of senescence in the winter and early spring as the excess growth rots away. Rather than increasing light interception, this “transitory senescence period” reduces it in the early spring, nullifying all the benefits of planting earlier.
Over the last season the research team have been exploring ways of manipulating the crop canopy to keep it greener through winter and spring. Aside from defoliation, other options they have considered include cultivar selection and plant growth regulator programmes. The two slow developing cultivars, Wakanui and Inferno, were compared last season. For March sow dates they maintained similar canopy greenness and had similar average yields of about 16 t/ha. Although there was no difference between the two cultivars, we believe germplasm more suited to early sowing may offer a way forward. The PGR trial found that increasing the intensity of the PGR programme from two to four sprays appeared to benefit the February sow date only.
For the 2016-17 season a range of cultivars selected by breeders and seed companies are being screened from an early March sow date.
For further information contact Rob Craigie: rob.craigie@far.org.nz
