Estimates of Self-pollination in Pecan Orchards in the Southeastern United States

Wood, Bruce W.; Marquard, Robert D.

doi:10.21273/hortsci.27.5.406

Cited by 9 publications

(10 citation statements)

References 7 publications

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“…Cross-pollination of pecan ensures heterozygous progeny (Marquard, 1988;Wood and Marquard, 1992) and increases survival of seedlings with suffi cient genetic diversity to endure the selective pressures imposed throughout a wide climatic range. Cross-pollination is promoted by dichogamy.…”

Section: Reproductive Strategiesmentioning

confidence: 99%

Adaptability of Pecan as a Species

Sparks¹

2005

HortSci

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Pecan [Carya illinoinensis (Wangenh.) C. Koch] is indigenous to the Mississippi River drainage system of the United States. Climate in the native pecan region ranges from humid to semiarid and from mild to harsh winters. Rainfall is bimodal with peaks in March to April and in August to September. Pecan is site specific and is the climax tree species on loamy, well drained, first bottom river land with a relatively high water table. Detrimental effects from pecan's shade intolerance from its more vigorous, sympatric species are minimized as these species are specific to differ sites. Pecan's deep and phreatophytic rooting habit ensures soil moisture during drought periods and facilitates pecan's survival in semiarid regions. Root development in the humus-surface layer ensures nutrient uptake from the most nutrient rich layer of the soil and, when the lower soil profile is saturated, aeration for the roots and water and nutrient uptake. The bimodal rain pattern replenishes soil profile moisture and its timing ensures seed germination, stand establishment, well-developed seed, and minimal drought stress. Natural selection for freeze tolerance and for minimum fruit development time allows survival in areas with harsh winters and short growing seasons. Regulation of seed germination and budbreak by heating and chilling results in pecan being native in cold and warm climates, greatly increasing the native range. The northern limit for pecan is dictated by heat units; the southern limit is restricted by lack of bimodal rains and vivipary. Reproductive stress is caused by the high lipid content of seed, but is counteracted by a long juvenile growth period of the seedling, by a small nut size and low percentage kernel, and by “off” production years of the tree. Nut and percentage kernel decrease as the growing season decreases which contributes to species survival in geographical regions with a short growing season. Selection for small nuts with low percentage kernel is enhanced by predators. Tree reserves are depleted by heavy production during “on” years and are replenished during “off”years. Perpetuation of pecan forests is apparently from sib/half sib seedlings following predator satiation while dissemination into new areas may be mainly by predators. Pecan and its pests successfully co-exist. Major defense against fruit feeders is escape in time, leaf feeders by biological associations and accommodation, and leaf diseases by confrontation. Heterozygous progenies from cross-pollination provide ample genetic diversity for continuous pecan selection to endure pressures imposed throughout a wide climatic range. Ecological adaptions within native pecan forests should be used in developing and maintaining commercial pecan orchards.

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Section: Reproductive Strategiesmentioning

confidence: 99%

Adaptability of Pecan as a Species

Sparks¹

2005

HortSci

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“…Isozyme analyses in pecans can now be used to help substantiate parentage, verify cultivars, and estimate self-pollination rates (Marquard, 1988;Wood and Marquard, 1992). Cultivars possessing low-frequency alleles (ie., <5%) would be useful in studies of gene flow and reproductive biology.…”

Section: Resultsmentioning

confidence: 99%

Identifying Pecan Cultivars by Isozymes and Inheritance of Leucine Aminopeptidase

Marquard¹,

Grauke²,

Thompson³

et al. 1995

jashs

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More than 170 pecan [Carya illinoensis (Wangenh.) K. Koch] cultivars were evaluated formalate dehydrogenase, phosphoglucose isomerase, phosphoglucomutase, leucine aminopeptidase (LAP), and diaphorase (DIA). Isozymes of LAP were observed in two regions after starch gel electrophoresis. The faster region of activity (Lap-1) was polymorphic and consistently expressed in leaves, wood, and roots. Controlled crosses suggest that Lap-1 is simply inherited and controlled by at least two alleles. DIA was well resolved and storable only from leaf material and produced a complex banding pattern. The ability to differentiate among cultivars by isozymes was good. The 177 cultivars sorted into 72 classes. Forty of the cultivars (23%) possessed a unique series of isozyme patterns. Most cultivars (124 of 177) shared common banding patterns with less than four other cultivars. From the inheritance models of four isozymes, some historical pedigrees can be questioned. Most notably,' Western Schley' could not have been parented by `San Saba' based on the inheritance of Mdh-1 and Lap-1.

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“…This was partially based on observations of the great abundance (Woodroof, 1924(Woodroof, , 1930 and mobility (Woodroof and Woodroof, 1927) of pollen produced by trees and its potential availability to regional orchards. Nevertheless, the detection of extensive self-pollination in many southeastern blocktype orchards by Wood and Marquard (1992) using isozyme techniques suggests that pollinizer-related crop losses are far more likely than commonly supposed and is especially likely to occur in block-type orchards. Thus, for the first time since the first half of the 20th century (Stuckey, 1916;Adriance, 1931;Romberg, 1931;Smith and Romberg, 1946) these findings not only raise the question of serious pollination problems in areas where pecan in commonly cultivated, but also quantified severity of problem in orchards typical of many within the region.…”

Section: Pollination Problemsmentioning

confidence: 99%

“…Pecan orchards in the U.S. were first established in the late 1800s and early 1900s. The importance of careful selection of cultivars to compensate for dichogamy and climatically induced variations in pollen maturity and dispersal patterns has been repeatedly stressed (Adriance, 1931;Madden and Brown, 1975;Marquard, 1988;Romberg, 1931;Romberg, 1932, 1940;Stuckey, 1916;Wood 1997;Wood and Marquard 1992;Wood et al, 1997). Many of these original orchards are still cultivated.…”

mentioning

confidence: 99%

“…The frequency of off-type trees, due to graft failures was usually substantial, thus providing serendipitous and random sources of pollen within orchards. Recent investigations into poor fruit set and filling problems in orchards appearing to receiving near optimal culture found that cross-pollination remains a problem in many orchards (Marquard, 1992;Wood and Marquard, 1992;Wood, 1997). Pecan pollination characteristics and factors affecting pollination are therefore reviewed to provide insight into how to minimize pollination related crop losses.…”

mentioning

confidence: 99%

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Pollination Characteristics of Pecan Trees and Orchards

Wood¹

2000

horttech

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There is increasing evidence of substantial pollination related crop losses by pecan [Carya illinoensis (Wangenh.) K. Koch] orchards. These most likely occur in block-type orchards consisting of only one or two cultivars, but can also occur at locations with a great number of different genotypes nearby. Main crop cultivars should generally be within about two rows of pollinizers to ensure cross-pollination. Thus, block widths exceeding about four rows between pollinizers are especially likely to exhibit serious pollination problems. Scattered trees of off-type genotypes are potentially of major importance as backup orchard pollinizers. Tree age/size and spring temperatures influence the characteristics of flower maturity windows and are probably primary factors contributing to pollination-related fruit-set losses in many block-type orchards. Flower maturity tends to be earlier in older/larger trees while warmer springs accelerate catkin development relative to that of pistillate flowers. Because of substantial variability in relative differences associated with initiation and duration of flower maturity windows within either protandrous or protogynous flowering types (i.e., Type I or II), selection of complementary pollinizers should be based on the relatively high resolution 30-class flowering classification system rather than the traditional low resolution 2-class system. Other factors sometime causing pollination related crop losses are either abnormally wet weather or strong dry winds during the pollination period or abnormally warm or cool springs. Pollination problems can be visually detected by noting premature non insect related post pollination fruit drop or diminishing fruit set with increasing distance from pollinator trees or off-type genotypes within the orchard.

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Estimates of Self-pollination in Pecan Orchards in the Southeastern United States

Cited by 9 publications

References 7 publications

Adaptability of Pecan as a Species

Adaptability of Pecan as a Species

Identifying Pecan Cultivars by Isozymes and Inheritance of Leucine Aminopeptidase

Pollination Characteristics of Pecan Trees and Orchards

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