An average of >20% seedless (blank) fruit are produced annually in Pistacia vera cv. Kerman. The degree of blank production was reportedly not related to individual tree yields and, therefore, was not thought to be resource limited (Crane, J.C., 1973. HortSci. 8:388-390). In two crop years, we studied the variability in percentage blanking among individual shoots characterized by widely varying leaf area to fruit (L/F) ratios. L/F ratios were related inversely to the percentage of blank fruit produced. Thus, individual branches behaved somewhat autonomously with respect to blanking. Our data are consistent with the view that embryo development was resource-limited. Although `Kerman' exhibits the potentiality for parthenocarpic fruit set, the hissed distribution of seedless fruit within the tree presumably indicates that blanking is an example of stenospermocarpy. Blanking does not result primarily from inadequate pollination under typical field conditions.
Steven A. Weinbaum and T.T. Muraoka
Stephen M. Southwick, James T. Yeager, and J. Grant
The effect of initial heading height on primary branch development in ‘Bing’ sweet cherry (Prunus avium) was examined in the first year of growth. Trees headed 51 cm above the soil surface resulted in fewer primary branches produced by 1-year-old trees than those headed at 75 cm and delay-headed at 142 cm, respectively. Branches on trees with lower heading height had narrow angles and longer branches than those on trees that were headed higher. Trees delay-headed at 142 cm produced the greatest number of primary branches with the widest crotch angles and shortest branch length. Branches were distributed along the entire length of the main leader in each treatment, but more branches with narrow angles and longer lengths were located 50 cm below the heading cut along the tree trunk. A significant linear relationship existed between branch angle and branch length in the 0- to 50-, 50- to 100-, and 100- to 142-cm sections along the tree trunk.
Nobuko Sugimoto, A. Daniel Jones, and Randolph Beaudry
2-methylbutyl acetate, which confer typical apple aroma characteristics ( Paillard, 1990 ). The esters are largely composed of either straight- or branched-chain alkyl (alcohol-derived) and alkanoate (acid-derived) groups. The ester product is formed
Don C. Elfving and Dwayne B. Visser
Sweet cherry trees exhibit strong apical dominance, producing vigorous, upright shoot growth with limited lateral branching, particularly in young trees ( Elfving and Visser, 2006 ; Jacyna, 2002 ; Jacyna and Puchała, 2004 ; Jacyna et al., 2005
Brent Tisserat and Mikeal Roose
Some Citrus spp. and cultivars exhibit juice vesicle branching. In this study, we determined that the branching trait is inheritable. The mode of inheritance of this trait was analyzed in progenies from various 2x × 2x and 2x × 4x citrus crosses. No consistent model for inheritance of branching has been found, although some crosses do suggest simple inheritance. We found that if one parent is a pummelo, even if this parent does not exhibit the branching trait itself, branching may be inherited by a substantial portion of the progeny, suggesting that more than one locus is involved in this trait.
Jeff S. Kuehny and Patricia Branch
Lateral branches of poinsettia tend to break from the main stem as plants reach maturity. The cause of poor stem strength is not known; however, suggested factors implicated in poor stem strength are: rate of nitrogen fertilizer used, type of plant growth regulator used, crowding of plants, or stem diameter of the cutting. Four different experiments were conducted to determine if these factors affected stem strength of poinsettia. Experiment 1: `Freedom Red', `Success', `V-17 Angelika Red', `Red Sails', `Nutcracker Red', `Cortez', `Maren', and `Red Splendor' poinsettia were fertilized with 20N–1P0–20K at 75, 75/125, 125/200, or 200 ppm N drip fertigation with zero leachate. Experiment 2: Three plant growth regulators were applied to `Pearl' and `Jolly Red' poinsettias. Experiment 3: `Freedom Red' plants were grown in a 625, 900, 1225, or 1600 cm2 area. Experiment 4: Rooted `Freedom Red' cuttings with stem diameters of 4.5, 5.5, 6.5, or 7.5 mm were used. A force meter was used to determine the strength of each lateral on the main stem of the six replications in each experiment. The lower laterals had the least stem strength and the top lateral had the highest stem strength for all treatments in all experiments. The stem strengths of some cultivars in experiment 1 were stronger at the lower fertilizer rates. Type of plant growth regulator had no significant affect on most poinsettia cultivars. The stem strengths of poinsettias in experiments 3 and 4 varied according to which lateral was measured.
Henry Donselman and Timothy K. Broschat
Dracaena marginata Lam., grown continuously in full sun, produced an average of 4.3 basal branches per plant, while plants grown under 50% shade produced no basal branches. Acclimatized plants with a maximum number of shoots can be produced in 20-liter containers in 12 months by growing in full sun for 9 months to induce basal branching followed by 3 months in 50% shade for acclimatization.
W. J. Carpenter, R. C. Rodriguez, and W. H. Carlson
Foliar sprays of 6-(benzylamino)-9-(2-tetrahydropyranyl)-9H-purine (PBA) at 200 or 300 ppm and 6-benzylamino purine (BA) at 500 or 1000 ppm, caused the development of 90% or more of the lateral branches of ‘Annette Hegg’ and ‘Dark Red Annette Hegg’ poinsettia (Euphorbia pulcherrima Willd.) while 2 to 4 lateral branches developed from terminal stems of “Eckespoint C-l Red” near the position of the apical meristem. (2-Chloroethyl)phosphonic acid (ethephon) sprays increased lateral branch development significantly above the control treatment but less than PBA or BA while 2, 3, 5-triiodobenzoic acid (TIBA) produced only slightly more branches than the control.
Wayne J. Bourgeois and Alvin J. Adams
Scaffold branch irrigation significantly enhanced tree survival and decreased the percentage of canopy that was killed on young Washington navel orange (Citrus sinensis) and Owari satsuma (Citrus unshiu) trees subjected to — 8.9°C during a 1985 freeze. Scaffold branch irrigation has shown considerable potential as a method of freeze protection for Louisiana citrus producers.
Michal Fishler, Eliezer E. Goldschmidt, and Shaul P. Monselise
The dependence of fruit growth of grapefruit (Citrus paradisi Macf.) upon leaf area was investigated on girdled branches by manipulating leaf and fruit numbers. Leaf areas of 2.0 ± 0.5 m2 per fruit were found to be saturating with regard to fruit growth rate and size. Fruit on internal, shaded branches required larger leaf areas. Fruit on girdled branches weighed 44 to 119% more than fruit in ungirdled branches, which had leaf areas of 0.35 to 0.55 m2 per fruit. This indicates that leaf area is one of the factors limiting fruit growth. Starch accumulated in thin twigs during the fruit growth season, forming a saturation curve similar to those obtained for fruit size when plotted against leaf area per fruit. Increasing leaf area per fruit could involve a decrease in photosynthetic activity, a possibility which now is being investigated further.