Compensation for reduced stands in burley tobacco experiments

Field experiments were conducted during 1968 and 1969 to study the effect of missing plants on the yield of hurley tobacco plots, to develop a procedure to adjust yield on the basis of stand, to test the procedure under actual field conditions, and to study the nature of yield compensa-tion by plants adjacent to missing plants. Burley 49 and MS Burley 37 x L8 cultivars were used with plants removed in five different patterns at four stages of growth. Both the patterns in which plants were missing and stages of plant removal had significant effects on plot yields. The estimated amount of compensation by plants adjacent to missing plants was calculated and from this information a formula was developed to adjust yield on the basis of stand. The relative efficiency of the proposed procedure was 149 compared to 139, 129 and 100 for Crews' procedure, covariance analysis, and no adjustment, respectively. To determine the nature of compensation by plants adjacent to missing plants, standard partial regression coefficients were computed. They were 0.0180 for length of leaf, 0.2437 for plant height, and 0.5972 for width of leaf. This indicates that leaf width and plant height exert a large influence on compensation with the major influence being the leaf width component of leaf size.