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achieve the accepted product form for retail sales in 4- to 5-inch-diameter containers. Paclobutrazol is a widely used plant growth regulator for size control of commercially produced ornamental crops such as bedding plants, bulb crops, herbaceous

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`Gala' apples are increasing in worldwide popularity. Despite this, little information on the cultivars vigor, precocity, or interaction with size-controlling rootstock is available. In 1985, a factorial planting was set to study these variables. `Gala' and `Golden Delicious' trees were found similar in precocity. Cumulative yields were about 20 kg per tree after the fifth leaf. `McIntosh' and `Delicious' trees were less precocious. `Gala' trees were also quite vigorous. Tree size and yield efficiency data will be presented, comparing `Gala' with other cultivars budded onto M 7a, MM 111, or propagated in tissue culture as scion-rooted plants. Tree management techniques have been identified that decrease fruit size. Trees budded onto precocious rootstock, and fruited heavily on one-year wood produce small-sized fruit. This tendency is pronounced on trees fruiting in the second leaf, or on older trees damaged by late-spring freezes that reduce the proportion of crop borne on spurs.

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Vegetative growth of two peach (Prunus persica L. Batsch) cultivars Flavorcrest and Loadel growing on six different rootstocks (`Nemaguard', `Hiawatha', K-146-43, K-146-44, P-30-135, and K-119-50) was analyzed during the third season of growth in an experimental orchard at the University of California Kearney Agricultural Center near Parlier, California. Seasonal trunk cross-sectional area, shoot and internode growth, diurnal stem extension growth rate and summer and dormant pruning weights were measured to determine extent of size-control imparted by the experimental rootstocks compared to the trees on the `Nemaguard' control and to characterize the nature of the sizecontrolling response. Trunk cross-sectional area growth of trees on the two smallest rootstocks (K-146-43 and K-146-44) was only 25% to 37% of the growth of trees on `Nemaguard', while trees on the other three rootstocks provided an intermediate level of size control. Generally, the seasonal patterns of shoot growth did not vary substantially among trees on the different rootstocks, but average shoot and internode lengths did correspond with tree size. Vigorous watersprout growth was decreased by more than 80% in the trees on the least vigorous rootstocks compared to trees on `Nemaguard' resulting in major reductions in the extent of summer and winter pruning weights. Variations in vegetative shoot growth appeared to correspond to variations in daily shoot extension growth rates but more research is needed to explore these relationships.

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Abstract

Tree size and performance were summarized for five-year-old apple trees, with a range of vigor, in several cultivars on several size-controlling rootstocks. Trunk cross-sectional area (TCSA) of trees on EMLA 9 was 86% greater than those on M 9, while trees on EMLA 27 had a 48% smaller TCSA than M 9. The percentage of flowering was greatest on trees on M 9 compared to EMLA 9 and 27; greatest on Clark (C) 54 compared to C 6 and C 43; and least on seedling compared to MM 111, MM 106, and M 7. Trees on EMLA 9 and M 9 had high-yield efficiency (cumulative yield/TCSA), whereas those on EMLA 27 were less yield-efficient. Trees on seedling stock were less efficient than those on MM 111, MM 106, and M 7. Smallest trees based on TCSA were noted for both ‘Oregon Spur Delicious’/EMLA 27 and ‘Starkrimson’/C 54, whereas the largest trees were ‘Starking Delicious’/Merton 793.

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Abstract

One-year-old Mailing (M) 26 and Mailing Merton (MM) 111 apple rootstocks (Malus sp) were planted in pots in a greenhouse in March and harvested monthly from May to October. Samples of the shoot tip, stem bark, and new and old roots were collected for PVP-bonded and simple phenol analyses. The PVP-bonded phenols were highest in the shoot tip and lowest in the old roots. There was no consistent relationship with rootstock or time of collection. Five phenols were found in the shoot tip, 8 in the bark, and 8 in the new roots, including protocatechuic, ferulic, and benzoic acids. Benzoic acid was found only in the new roots. Phloridzin composed more than 90% of all the simple phenols found and was higher in MM 111 than in M 26 rootstock. The other phenols were not consistently higher in either rootstock and had few trends with time of collection. No direct relationship was found between phenol levels and dwarfing characteristics.

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The effect of rootstock on the flowering and fruiting response of sweet cherries (Prunus avium L.) was investigated using 4-year-old branch units. The cherry rootstock Edabriz (Prunus cerasus L.) affected the flowering and fruiting response of `Burlat' sweet cherry compared to Maxma 14 and F12/1. Branches of trees on Edabriz had more flowers, more flowers per spur, more spurs, more fruit, higher yields, smaller fruit, and a reduced fruit set compared to the standard rootstock, F12/1. One-year-old branch sections had more flowers and fruit, higher fruit weight, and heavier fruit size compared to older branch portions.

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Mature fruit size and shape are important traits of most melon types. Our objective was to identify RAPD markers associated with major QTL affecting fruit weight, length, diameter and shape by means of bulked segregant analysis in an F2 population from the ananas melon cross of Deltex (larger fruit size) × TGR1551 (smaller fruit size). Clear separations for fruit weight, length, diameter, and shape between Deltex and TGR1551 were observed. Continuous distributions for fruit weight, length, diameter and shape were found in the F2 population indicating quantitative inheritance for the fruit traits. Significant positive correlations were detected between fruit weight and shape traits (r = 0.73 to 0.80). A significant positive correlation was observed between fruit weight and glucose (r = 0.35) or fructose (r = 0.25), whereas no correlation was noted between fruit weight and sucrose or total soluble solids. Two small and large bulks for fruit weight and shape were developed from F2 plants. A total of 240 primers were used to simultaneously screen between the small and large bulks, and between Deltex and TGR1551. Twenty-six RAPD markers were polymorphic for the small and large bulks. Ten markers were found to be significantly and consistently associated with fruit size and shape traits on the basis of simple linear regression. Of the 10 markers associated, four displayed an amplified DNA fragment in the small bulk, while six showed an amplified DNA fragment in the large bulk. The associated marker OJ07.350 explained 15% to 27% of the phenotypic variation for the fruit traits. These markers associated with QTL for melon fruit size and shape are expected to be useful in melon breeding programs for modifying fruit size.

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After 12 growing seasons, `Starkspur Supreme Delicious' apple trees on 9 rootstock genotypes from very vigorous (MAC 24) to very dwarfing (M.27 EMLA) were divided into branches, trunk, rootstock shank, and roots, and total fresh and dry weights of each component determined. Final tree dry weight (DW) ranged from 2 kg (M.27 EMLA) to 90 kg (MAC 24). Both total top DW and total tree DW (including roots) were closely and linearly related to final trunk cross-sectional area (TCSA). Both total cumulative fruit fresh weight and DW per kg final tree DW increased curvilinearly with smaller final TCSA. The percentage of cumulative fruit DW plus final tree DW in fruit increased curvilinearly with smaller final TCSA. Although 9 distinct rootstock genotypes of widely different vigors were included, the close relationships of tree DW and the distribution of DW between fruit vs. wood to final TCSA suggested that rootstock effects on both vigor and productivity were mediated through a single overall mechanism.

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In 1987, a study consisting of 3 training systems (TS) [Supported modified leader (S), Free Palmette (P) and Mini-Tatura (MT)] with Anjou (A), Bartlett (B) and Flemish Beauty (FB) on Quince A & C and Provonce C134, in a high and ultradensity planting, was initiated on a fine sandy loam soil. Blossoms were counted and removed during 1988 to 1990 seasons. Palmette TS increased bloom efficiency (BE) but did not affect the number of florets/cluster. Quince C produced higher BE than either QA or C134. Bartlett had the highest BE followed by A & FB. Anjou exhibited more florets/cluster than either B or FB. Rootstock or TS did not influence this variable.

Irrespective of rootstock and training, the largest trees were FB followed by A & B. Quince C produced trees smaller than QA & C134. Mini-Tatura reduced tree size significantly compared to S & P. The cumulative yield for 1991 & 92 (5th and 6th leaves) was 85 tonnes/ha for MT compared to 35 & 37 for S and P respectively. Quince clones had no effect on yield, but A was significantly less productive than B or FB. Cultivar, rootstock or training did not affect mean fruit weight during 1992. Bartlett had higher number of pears/tree compared to A & FB. Palmette training system produced more pears per tree in comparison to S and MT.

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spur. Control trees were left unthinned. Prebloom thinning had previously resulted in significant fruit size differences ( Lang and Ophardt, 2000 ; Whiting and Lang, 2004 ). However, for some genotypes, thinning did not result in a significant fruit

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