dwarfing rootstocks decreased during senescence, whereas N in flower spurs increased. This translocation of N from leaves to storage tissues before leaf abscission is an important source of N for spring growth, just as if a N fertilizer were applied
Theoharis Ouzounis and Gregory A. Lang
Takuya Tetsumura, Ryutaro Tao, and Akira Sugiura
A potentially dwarfing rootstock for japanese persimmon (Diospyros kaki L.) was propagated by single-node stem cuttings taken from root suckers. When a mature tree was cut down at ground level and part of the roots was exposed to the air, numerous suckers formed on the exposed parts of the roots. Single-node stem cuttings 3 to 4 cm (1.2 to 1.6 inches) long survived and rooted better than 10-cm (3.9-inch) and 25-cm (9.8-inch) leafy stem cuttings with several buds. Dipping cuttings in 3000 mg·L-1 (ppm) IBA for 5 s or in 25 mg·L-1 IBA for 24 h resulted in similar rooting. Most of the single-node stem cuttings taken in late-June and July survived and rooted well, whereas those prepared in late August rooted poorly and few survived. The survival and rooting percentages were unaffected by the position on the suckers (top vs. base) from which cuttings were taken. High relativehumidity in the propagation frame appeared to enhance survival and rooting. This clonal propagation method will make a rapid multiplication of japanese persimmon, a difficult-to-root species, possible. Chemical name used: indole-3-butyric acid (IBA).
Mercy A. Olmstead, N. Suzanne Lang*, Frank W. Ewers, and Shirley A. Owens
Dwarfing rootstocks in sweet cherry (Prunus avium L.) have been planted worldwide. No single theory has emerged to answer why scion dwarfing occurs in fruit trees. This research examines the vascular pathway in a dwarfing cherry system to determine if physical limitations alter water transport as a possible dwarfing mechanism. Second-leaf `Lapins' trees grafted onto Gisela 5 (Gi5; dwarfing) and Colt (vigorous) rootstocks were field-grown in East Lansing, Mich. During maximum shoot elongation, trees were dug, placed into containers with safranin dye solution (0.1% w/v) for 6 hours and then removed for division (3-5 cm in length) based on location in scion, graft union, and rootstock tissue. Tissues were sectioned using a sliding microtome (120 μm) for examination with a laser confocal microscope (Zeiss LSM Pascal). Mean stem area and vessel diameter were measured; and mean hydraulic diameter was calculated for vessels in the area of dye translocation. Overall, Lapins/Gi5 stem area in the graft union was larger compared to Lapins/Colt; however dye translocation in Lapins/Gi5 was reduced compared to other tissues in the tree. Confocal microscopy indicated dye uptake through the grafted region was more uniformly distributed in Lapins/Colt than in Lapins/Gi5, with dye accumulation in areas of maximum translocation. Vessel diameter did not differ in these areas of translocation. However, in both combinations there was a reduction in mean hydraulic diameter of graft union sections, suggesting a reduction in vessel efficiency to translocate water in this region. Vascular system anomalies were more frequent in Lapins/Gi5, disrupting acropetal dye translocation. This suggests the greatest reduction in vascular transport is in Lapins/Gi5.
Li Ma, Chang Wei Hou, Xin Zhong Zhang, Hong Li Li, De Guo Han, Yi Wang, and Zhen Hai Han
genotypes, the scion and the rootstock. The extensive use of dwarfing apple rootstocks has launched a major shift into high-density cultivation since the pioneering innovation of the East Malling series of dwarfing rootstocks ( Jackson, 1989 ; Norelli et al
François Mademba-Sy, Zacharie Lemerre-Desprez, and Stéphane Lebegin
to 2.5 m at adult age ( Bitters et al., 1979 ). FD would be one such dwarfing rootstock. Originating from Japan, it was used to produce ornamental potted plants and introduced in the United States by Walter S. Swingle in 1915; it remained for long as
An orchard trial was established by planting an orchard with between-row intervals of 4 m. The French Axe was trained for trees with intervals in the row of 1 and 1.5 m. The hedgerow was used for treatments of 2–2.5 and 3 m between trees in the row. Semi-dwarf rootstock of Bud54-118 and dwarf one Bud62-396 were used. The growth of of these rootstocks was analogous to MM106 and M26, respectively. The trunk cross-sectional area of 7-year trees on 54-118 rootstock was 2.3 times more than on 62-396 for cv. Antey and 1.5 times more for cv. Tellisaare. The height of tree with French Axe crown at 7 years after planting on 54-118 rootstock reached 3.5–4 m. The height of tree was 0.5 m smaller on 62-396. The crown habit of tree on 62-396 rootstock was more comfortable for high -density orchard than trees on 54-118. The sum length of twigs that were cut out during 1993–96 to attain of normal density of crown was 2-4 times more than on 62-396 rootstock. Commercial fruiting of cv. Antey started at the 3rd leaf, but it was on 4th leaf for the more-dwarf rootstock 62-396. Average yield of fruit at 3–6 years after planting of cv. Antey for treatment of distance between trees in the row of 2 or 1.5 m was 6.8 kg/tree per year-1 for 54-118 rootstock, 3.4 and 3.5, respectively, for 62-396 rootstock. Yield at the 7th year after planting reached 24 and 32 kg on 54-118 rootstock, 16 and 15 kg on 62-396, respectively. Analogous date obtained for cv. Tellisa are. cv. Spartan on both rootstocks started to fruiting at 5-6 years after planting. The fruit quality was very high in all treatments of the trial.
Wesley Autio*, LaMar Anderson, Bruce Barritt, Robert Crass-weller, David Ferree, George Greene, Scott Johnson, Joseph Masabni, Michael Parker, and Gregory Reighard
`Fuji' apple trees [Malus ×sylvestris (L.) Mill. Var domestica (Borkh.)] on nine dwarfing rootstocks (CG.4013, CG.5179, G.16N, G.16T, M.9 NAKBT337, M.26 EMLA, Supporter 1, Supporter 2, and Supporter 3) were planted at 10 locations (CA, KY MO NC OH 2 in PA SC UT and WA) under the direction of the NC-140 Multistate Research Project. After four growing seasons (through 2002), largest trees were on CG.4013. Smallest trees were on M.9 NAKBT337, Supporter 1, Supporter 2, and Supporter 3. Trees on CG.5179, G.16 N, G.16T, and M.26 EMLA were intermediate. Cumulative root suckering was greatest from trees on CG.4013 and similar from the other rootstocks. CG.4013, CG.5179, and G.16T resulted in the greatest yields per tree in 2002, and M.26 EMLA, M.9 NAKBT337, Supporter 2, and Supporter 1 resulted in the lowest. Cumulatively, CG.4013 resulted in the greatest yields per tree, and M.26 EMLA resulted in the lowest. Rootstock did not affect yield efficiency in 2002, but cumulatively, Supporter 1, Supporter 2, and Supporter 3 resulted in the most efficient trees, and M.26 EMLA the least. Fruit weight in 2002 or on average was not affected by rootstock. Limited data will be presented on CG.3041, CG.5202, and CG.5935, which are planted only at some locations. Data for the fifth season (2003) will be presented.
Wesley Autio*, John Cline, Robert Crassweller, Charles Embree, Elena Garcia, Emily Hoover, Kevin Kosola, Ronald Perry, and Terence Robinson
`McIntosh' apple trees [Malus ×sylvestris (L.) Mill. Var domestica (Borkh.)] on 10 dwarfing rootstocks (CG.3041, CG.4013, CG.5179, CG.5202, G.16N, G.16T, M.9 NAKBT337, Supporter 1, Supporter 2, and Supporter 3) were planted at 10 locations (MA, MI MN NS 2 in NY ON PA VT and WI) under the direction of the NC-140 Multistate Research Project. After four growing seasons (through 2002), trees on CG.5202 and CG.4013 were significantly larger than those on all other rootstocks. Smallest trees were on M.9 NAKBT337. Trees on other rootstocks were intermediate. Rootstock did not influence cumulative root suckering. Yield per tree in 2002 was greatest from trees on CG.4013 and lowest from trees on M.9 NAKBT337; however, cumulatively, trees on M.9 NAKBT337 and CG.4013 yielded the most. Yield efficiency in 2002 was not affected by rootstock. Cumulatively, rootstock had very little effect, but trees on CG.5202 were the least efficient. In 2002, M.9 NAKBT337, CG.3041, and Supporter 2 resulted in the largest fruit, and CG.5179 resulted in the smallest. On average, M.9 NAKBT337 resulted in the largest fruit, and G.16T resulted in the smallest. Limited data will be presented on CG.5935 and M.26 EMLA, which are planted only at some locations. Data for the fifth season (2003) will be presented.
Suxiao Hao, Yanfen Lu, Jing Liu, Yufen Bu, Qi Chen, Nan Ma, Zhiqin Zhou, and Yuncong Yao
, the regulation function of GID1 in the determination of the plant growth traits of dwarfing rootstocks is still unclear. Plant growth is also controlled by the regulation of different hormone signals, including auxin, brassinolide, and abscisic acid
Matthew D. Whiting and Gregory A. Lang
Canopy fruit to leaf area ratios (fruit no./m2 leaf area, F:LA) of 7- and 8-year-old `Bing' sweet cherry (Prunus avium L.) on the dwarfing rootstock `Gisela 5' (P. cerasus L. × P. canescens L.) were manipulated by thinning dormant fruit buds. F:LA influenced yield, fruit quality, and vegetative growth, but there were no consistent effects on whole canopy net CO2 exchange rate (NCERcanopy). Trees thinned to 20 fruit/m2 LA had yield reduced by 68% but had increased fruit weight (+25%), firmness (+25%), soluble solids (+20%), and fruit diameter (+14%), compared to unthinned trees (84 fruit/m2). Fruit quality declined when canopy LA was ≈200 cm2/fruit, suggesting that photoassimilate capacity becomes limiting to fruit growth below this ratio. NCERcanopy and net assimilation varied seasonally, being highest during stage III of fruit development (64 days after full bloom, DAFB), and falling more than 50% by 90 DAFB. Final shoot length, LA/spur, and trunk expansion were related negatively to F:LA. F:LA did not affect subsequent floral bud induction per se, but the number of flowers initiated per bud was negatively and linearly related to F:LA. Although all trees were thinned to equal floral bud levels per spur for the year following initial treatment (2001), fruit yields were highest on the trees that previously had no fruit, reflecting the increased number of flowers initiated per floral bud. Nonfruiting trees exhibited a sigmoidal pattern of shoot growth and trunk expansion, whereas fruiting trees exhibited a double sigmoidal pattern due to a growth lag during Stage III of fruit development. Vegetative growth in the second year was not related to current or previous season F:LA. We estimate that the LA on a typical spur is only sufficient to support the full growth potential of a single fruit; more heavily-set spurs require supplemental LA from nonfruiting shoots. From these studies there appears to be a hierarchy of developmental sensitivity to high F:LA for above-ground organs in `Bing'/`Gisela 5' sweet cherry trees: trunk expansion > fruit soluble solids (Stage III) > fruit growth (Stage III) > LA/spur > shoot elongation > fruit growth (Stages I and II) > LA/shoot. Current season F:LA had a greater influence on fruit quality than prior cropping history, underscoring the importance of imposing annual strategies to balance fruit number with LA.