Yield physiology of barley under no-tillage system and different date of planting

Studies on the differences in yield physiology of BRB.2 and BRB.9 barley cultivars grown under no-tillage and different planting date were carried out at the experimental site of Agronomy Department, Faculty of Agriculture, Chiang Mai University during November, 1995-April, 1996. Results showed that plant population per unit area, height, leaf area index (LAI) and average of this two barley yield was not significantly different under tillage and no-tillage treatments. The average yield under tillage method was 194 kg per rai whereas in the no-tillage treatment yield was 192 kg per rai. BRB.2 grown on 29 November produced the high average yield of 246 kg per rai. For BRB.9, it should be grown on 13 December which average yield of 208 kg per rai. As far as yield component is concerned, spike number per unit area was not significant different among the method of land preparation and cultivars but will effect on seed number per spike and 1000 grain weight. It was found that when drilled the barley seeds into no-tillage plot resulted in higher seed number per spike and 1000 grain weight. Futher studies on the crop growth rate of different organs and the partitioning coefficient was found that the crop growth rate of each parts (leaf, stem, ear (spike), grain and total parts) of these two cultivars grown under no-tillage method was not significant different from the tillage treatment. BRB.2 grown on 29 November under no-tillage produced the highest seed growth rate of 17.16 gm/square m/da. It was also found that under no-tillage method have a higher partitioning coefficient than the tillage one. BRB.2 which grown on 29 November partitioned of it assimilate to the grain as high as 97 percent as compared to the tillage treatment which partitioned only 73 percent. The partitioning coefficient of BRB.9 cultivar which grown on 13 December under no-tillage have 100 percent of its photosynthate were being used for grain filling as compared to the tillage method which partitioned of only 78 percent.