ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Prediction of site index and apple rootstock performance from environmental variables.

Olien, W. C.; Ferree, D. C.; Bishop, B. L.; Bridges, W. C., Jr.;

Fruit Varieties Journal Year: 1995 Vol: 49 Issue: 3 Pages: 179-189 Ref: 16 ref.

1995

บทคัดย่อ

Previously, stability analysis models were developed for 9 rootstocks tested in 19 apple-producing states which demonstrated significant rootstock-site interactions for cumulative yield (CY) and trunk cross-sectional-area (TCSA) [see Fruit Varieties Journal (1991) 45, 208-212]. A key input in these models is site index (SI), estimated from the mean for rootstocks within site. This study aimed to extend the usefulness of these models by developing further models to estimate SI for untested sites from climate variables. Prediction of SI from mean daily maximum temperature (T) and total moisture (M; sum of precipitation and irrigation) was evaluated over 5 periods based on previous work and on approx. phenological phases of the apple tree over the geographic area included in this study: A = Dec.-Jan. (dormant), B = Feb.-Apr. (prebloom), C = May-June (set), D = July-Sep. (growth to harvest), and E = Oct.-Nov. (postharvest to leaf senescence), resulting in 10 climate-time variables for model developm

ent. Complete records of T and M were available from 11 and 9 states, respectively. SITCSA was not significantly correlated with any T or M variable and therefore may have been influenced more by soil factors or deviations in orchard management practices than by climate. SICY was well correlated with TC, TD and MC, but TC and MC were strongly collinear. Further model development concentrated on prediction of SICY from T variables over data from 10 states (with California removed as an outlier). All 1-, 2- and 3-variable multiple regression models were evaluated. It was concluded that SICY was best predicted from a linear relationship with TC.