PREDICTION OF REPRODUCTIVE GROWTH-STAGES IN BARLEY

In barley, some herbicide and fertiliser recommendations are linked to reproductive development. Three cultivars of barley were sown on seve n different dates in 2 years in mid Canterbury, and their reproductive development related to more easily measured parameters such as calend ar time, thermal time, and leaf emergence. Morphological growth stages were recorded in both years, and, in addition, reproductive growth st ages were recorded in the second year. Development time decreased with delayed sowing up to ''ear at 1 cm'', but not thereafter. However, th ermal development time with a base temperature of 4-degrees-C, and pho tothermal development time with a base temperature of 0-degrees-C and a base photoperiod of 8 h, were unaffected by sowing date. In both yea rs, thermal time from ear emergence (GS49) to hard dough (GS87) averag ed 460 day degrees above 4-degrees-C, and photothermal time 314 day de grees above 0-degrees-C adjusted for photoperiod. 'Magnum' took up to 88 day degrees above 4-degrees-C longer, and up to 55 day degrees abov e 0-degrees-C adjusted for photoperiod longer, to reach a particular g rowth stage than did 'Triumph', with 'Illia' generally being intermedi ate. Double ridge occurred when there were three or four fully expande d leaves; ear at 1 cm occurred between five and six leaves; apical pri mordium stage occurred between six and seven leaves; and first node oc curred about the same time that seven leaves had fully expanded.