The effect of some Cultural Practices on Nitrogen and Fruitfulness in the Sultana Vine

¹ C.S.I.R.O., Merbein, Victoria, Australia.

In a small field trial over two seasons, sowing a cereal crop between the rows of Sultana vines at the beginning of September, and turning it in in late November a few days after full flowering for the vines, led to reduced leaf nitrogen in the vines over the period of differentiation of inflorescence primordia. In the second season there was a 27% increase in bunches per vine on such vines, compared with vines treated according to good district practice and already yielding more than district average.

Since there was no sign of moisture stress due to the cereal, and no reduction in berry set, which is known to be affected by moisture stress, the increase in bunch number is associated with reduced nitrogen, but the treatment caused weakening of some of the vines and reduced yield in the following year and was discontinued. Further attempts to lower soil nitrogen enough to increase number without seriously affecting vine vigor have not succeeded.