Photoselective Nets Alter Apple Canopy Air Temperature and Carbon Translocation during Dormancy and Budbreak

Photoselective nets were used to examine apple shoot physiology during dormancy and budbreak. Two trials were conducted: one in the field and one in controlled conditions. In the first, three colored nets (red, blue, and white, shading 20%) covered sections of single trees, leaving an empty portion as control, from December to April. The white net increased canopy air temperature compared with the blue one. Differences were found in carbohydrate seasonal patterns; however, it appeared that soil temperature had higher impacts on sugar movement in the trees. No differences were found in bud phenology. In the second trial, cuttings were placed in boxes constructed with the same-colored nets and monitored from the end of February to April. Results showed differences in phenology and carbohydrate translocation. The white box hastened bloom and its cuttings had higher amounts of carbohydrates at the end of the trial. On the contrary, the blue box delayed bloom while resources were still being consumed and its cuttings had the lowest amounts of reserves at the end of the trial. These results add new insights on apple physiology under different light spectra and commercial applications should not be excluded for improving crop management.

Changes in direction of growth as induced by unilateral auxin application to apple shoots

Lanolin paste containing indoleacetic acid, applied unilaterally to the elongating internodes of apple shoot, caused a marked change in its direction of growth. Measurements taken during autumn have shown that the treated internodes were not longer than those of control shoots. There was a short zone a few cm above the treated area with inhibited internodes and small leaves. Possibilities for practical application of the described method exist.