A preliminary assessment of the adaptation of semi-dwarf wheat varieties to the Ord River valley

Abstract

In the 1966 dry season at Kimberley Research Station in the Ord River valley, the performance under irrigation of three semi-dwarf wheat varieties was compared with that of two Australian varieties at three times of sowing and three levels of nitrogen fertilizer in factorial combination. The general response of the semi-dwarf varieties to time of sowing did not differ from that of the Australian varieties. All varieties, at 0 and 160 lb an acre N, gave higher grain yields when sown in late May than when sown in mid-April or late June. At 320 lb an acre N, each variety gave approximately the same grain yield whether sown in mid-April or late May, with a lower yield from late June sowings. All varieties increased in grain yield between 0 and 160 lb an acre N, but when nitrogen was increased from 160 to 320 lb an acre, the yield of the Australian varieties declined while that of the semi-dwarf varieties either increased or remained approximately the same. As a group, the semi-dwarf varieties differed only from the Australian varieties in their ability to use a high uptake of nitrogen for grain production, in their greater harvest index, 2nd in their lower grab nitrogen content. The highest yields, 75-80 bushels an acre, were obtained from Mexico 120 and Chile 1B.