Shade treatments increased the length to diameter ratios and decreased stem-cavity depth of ‘McIntosh’ apples. Full-shade was more effective than partial-shade, and shading all year and early in the growing season affected apple shape more than shading after July 15.
Fruit elongation, stem length, and stem-cavity depth of ‘McIntosh’ apples were increased by some gibberellic acid (GA) treatments and decreased by a fall spray of N-di-methylaminosuccinamic acid (Alar). Summer sprays of Alar and thinning had no measurable effect on apple shape. Ringing increased fruit elongation. These results are consistent with the concept that endogenous gibberellins act to control apple shape.
‘Summerland’ (regular-bearing) and ‘Macspur’ (spur-bearing) apple trees (Malus domestica Borkh.) on Mailing (M) 26 rootstock were grown in pots under 4 shade treatments (100%, 88%, 50% and 12% full sun) and with grass, bare soil, and white plastic ground covers. ‘Macspur’ trees grew and flowered more than ‘Summerland’ trees. The 2 strains responded similarly to shade, but responded differently to ground covers. The greatest increase in fresh weight, number of shoots, and blossom clusters for ‘Macspur’ resulted with white plastic, while the least response was with grass; the reverse held for ‘Summerland’.
The 30 apple (Malus domestica Borkh.) rootstock candidates selected for cold hardiness, known as the Kentville Stock Clone (KSC), with `McIntosh' and `Delicious' as scion cultivars, were compared at 11 years of age for tree size, weight, fruit yield, and crop efficiency under field conditions. Trunk cross-section area and tree weight were highly correlated. Tree size was similar for the two cultivars in most cases and ranged in size from semidwarf to very vigorous. Cumulative yield efficiencies varied by nearly two-fold and were not correlated with tree size. The most efficient rootstocks were KSC 28, KSC 7, and KSC 6 in the semidwarf, semivigorous, and vigorous size classifications, respectively.
The precocity and productivity of 30 Kentville Stock Clone (KSC) apple (Malus domestica Borkh.) rootstocks, with `McIntosh' and `Delicious' as scion cultivars, were assessed independently of each other using a procedure involving computer-aided fitting of curves to yearly production data. A good fit to the data was obtained after biennial fluctuations in yield were removed by using a weighted, 3-year running average. For all 30 rootstocks combined, `McIntosh' was more precocious and reached a higher level of productivity compared to `Delicious'. There was poor correlation between precocity and productivity.
The effects of 30 Kentville Stock Clone (KSC) selections on fruit size and color of `McIntosh' and `Delicious' apples (Malus domestica Borkh.) were monitored over 5 years. Fruit size was influenced by the rootstock and, when averaged over the duration of the study, ranged from 108 to 132 g and 131 to 161 g for `McIntosh' and `Delicious', respectively. Variation in fruit size due to crop load (CL) was greater for `McIntosh' than for `Delicious'. Fruit color was influenced by the rootstock in all years for `McIntosh' and in 3 of 5 years for `Delicious'; it was strongly associated with tree size for `Delicious' only. An overall performance index, which also included price based on quality, was developed, and the best performers in each size group were: semidwarf KSC 18 and 28; semivigorous KSC 7, 11, and 24; and vigorous KSC 3 and 6.
3-indolebutyric acid (IBA) applied to the midvein of lowbush blueberry leaves stimulated lateral shoot development in what is normally an unbranched stem. IBA was effective when applied as a 2% mixture in either lanolin or water. The site of application and habit of shoot growth were shown to influence the treatment response.