Twenty variables were recorded on 15 apricot (Prunus armeniaca L.) genotypes differing in growth habit and blossom time to detect possible associations among morphological and phonological traits. The widest range of variability observed among phenotypes was for fruit size and factors associated with adaptation to local conditions, such as blossom season and yield potential as expressed by number of buds, flowers, and fruits per length of fruiting spurs. The most important morphological traits correlated with fruit weight were tree growth habit, apical and basal diameter of fruiting spurs, and bud and leaf size. Multivariate analysis allowed tree and variable grouping, which might encompass the basic criteria for apricot breeding programs in central México.
Sergio Tombesi, Bruce D. Lampinen, Samuel Metcalf, and Theodore M. DeJong
( Heerema, 2005 ) and that in many species the percent of flowers on a spur that produce fruit (spur relative fruit set) is largely influenced by spur light exposure and spur leaf area ( Stephenson, 1981 ), relative fruit set could be limited in spurs
Gerry Neilsen, Frank Kappel, and Denise Neilsen
of the two measurement trees in each treatment and replicate was randomly selected for dormant spur removal (extinction spur thinning). In late dormancy (early April), half of the fruiting spurs on 2-year and older wood was removed by pruning flush to
Marlene Ayala and Gregory Lang
. Actively growing aerial sinks (i.e., flowers, fruit, spurs, and ES) compete for the C provided by these different leaf populations ( Ayala and Lang, 2008 ; Roper et al., 1988 ). Roper et al. (1987) suggested that import of photoassimilates synthesized by
Timothy E. Elkner, J. A. Barden, M. M. Kushad, and D. D. Wolf
Fruiting spurs (`Red Prince Delicious') (RD) and shoots (`Sundale Spur Golden Delicious') (CD) with three leaf:fruit ratios and comparable nonfruiting spurs and shoots were girdled on 7 September 1988. An interaction between fruiting status and time existed for most parameters measured on both cultivars while there was no effect of leaf:fruit ratio. At 1 day after treatment (DAT) few differences existed due to fruiting status on either cultivar. At 8 DAT with RD and at 4 and 8 DAT with GD, Pn, transpiration (Tr), leaf water potential (ψ L), and nonreducing sugars were greater on fruiting than nonfruiting spurs and shoots while leaf resistance (RL), SLW, and starch were lower on fruiting spurs. In nonfruiting spurs and shoots Pn, Tr, and ψL tended to decrease while RL and SLW increased with time whereas m fruiting spurs and shoots most parameters remained constant. Total nonstructural carbohydrates, reducing sugars, and starch were greater in nonfruiting than fruiting spurs and shoots.
Esmaeil Fallahi, Denise Neilsen, Gerry H. Neilsen, Bahar Fallahi, and Bahman Shafii
treatments (data not shown). Trees with all drip systems tended to be more precocious and had higher yield per tree than trees with FS system when trees were young in 2004 ( Table 3 ). Water stress resulted in a higher production of fruiting spurs in trees
L. Corelli Grappadelli, A.N. Lakso, and J.A. Flore
The partitioning of photosynthates labeled by 14CO2 in exposed and shaded `Empire' apple (Malus domestica Borkh.) branches was examined at 1, 3, 5, and 10 weeks after bloom. Extension shoots, nonfruiting spurs, or fruiting spurs were labeled separately to examine which shoot types exported to the fruit at each time. The general partitioning patterns were observed with autoradiography, while label accumulation in fruit was determined by oxidation and scintillation counting. At each treatment time, half of the branches was preconditioned with artificial shade (to 35% full light) for 48 hours before labeling and returned to the shade for a 2-day translocation period. One and 3 weeks after bloom, extension shoots showed little export to fruit; nonfruiting and vigorous fruiting spurs exported label to weak spurs and extension shoot tips. Shade had no major effect on partitioning patterns at 1 and 10 weeks, but essentially eliminated export from extension shoots at 3 weeks and greatly reduced export to fruit 5 weeks after bloom, as observed on the autoradiograms. At 5 weeks after bloom, the shading effect was equal to a 2-week delay in export. By 10 weeks after bloom, all shoot types were exporting most of the 14C fixed to fruit. The photosynthate support of the fruit before fruit set seemed to strongly depend on the spur canopy, especially when the extension shoots were exposed to low light.
Renae E. Moran and Curt R. Rom
The relationship of variability in flowering and fruiting habit to canopy position and changing diurnal light and photosynthetic pattern was examined in 7 mature spur-type `Red Delicious'/MM106 apple trees. A .5×.5m column was placed in the north, south, east and west sections of tree canopies. Columns were subdivided by height with 3 study areas located at .25-.5m, 1.0-1.25m and 1.75-2.0m from the top of the canopy. In each, section, flowering index, fruit set, individual fruit weight and size, skin coloration, fruit soluble solids content, spur leaf area and spur bud diameter were determined. Photosynthetically active radiation and photosynthesis were measured from bloom through harvest correlated with variability in flowering, fruiting, spur quality and distribution of growth.
Jon M. Clements and Joseph F. Costante
A randomized complete block study was initiated in 1991 in a fifteen year old `Rogers Red McIntosh'/9-106 interstem orchard to investigate the effect of three dormant pruning regimes- an unpruned control, selectively thinned, and heavily structured or “tiered”, on tree canopy light distribution and fruit and spur quality. Fruit quality parameters being measured for the 1991 and 1992 harvests include skin color (% red blush), weight (g.), flesh firmness (kg.), soluble solids concentration (% Brix), and packout (% fancy grade). Pruning treatment effect on fruit spur quality, in terms of spur bud diameter (mm.) and spur efficiency (leaf dry weight/spur), is also being evaluated at time of harvest. Light distribution is being measured (% PAR, umol/s/m2.) within the tree canopy from petal fall through harvest. Preliminary findings indicate there is a difference in tree canopy light distribution and some fruit quality measurements, including red skin color, between pruning regimes. Complete analysis of results from 1991 will be presented.
I. Schechter, J.T.A. Proctor, and D.C. Elfving
Leaf characteristics of mature `Sturdeespur Delicious'/MM.106 apple trees (Malus domestica Borkh.) were studied in two experiments. In 1989 canopy foliage on fruiting trees was divided into shoot leaves, leaves on nonfruiting spurs, and leaves on fruiting spurs. Shoot leaves were the heaviest, the largest, and contained the highest internal gas volume and chlorophyll content. The two spur-leaf types differed in their leaf characteristics except for stomate density. In 1990 shoot and spur leaves on nonfruiting spurs on fruiting trees had lower leaf water content than those leaves on nonfruiting trees. All other shoot-leaf characteristics were similar. Leaves on nonfruiting spurs on nonfruiting trees were larger than those on fruiting trees.