We report the composition of the rare-earth (REE) metallome component of the foliar ionomes of pecan (Carya illinoinensis) and other North American Carya and how accumulation of specific REEs relate to ploidy level and to accumulation of essential divalent nutrient elements. REE accumulation within the foliar ionomes of 12 Carya species, growing on a common site and soil, indicates that REEs accumulate according to the Oddo-Harkins rule with Ce, La, Nd, and Y (Ce > La > Nd > Y) being the dominant REEs with accumulated concentration typically being La > Ce > Nd > Y > Gd > Pr > Sm > Dy > Er > Yb > Ho > Tb >Tm > Sc >Lu. Carya species quantitatively differ in accumulation of REEs with all but C. aquatica accumulating at much greater concentrations than non-Carya tree species and with tetraploid Carya accumulating to approximately twice the concentration as diploid Carya. Carya tomentosa was an especially heavy accumulator of REEs at 859 μg·g−1 dry weight, whereas C. aquatica was especially light at 84 μg·g−1. Accumulation of REEs was such that any one element within this elemental class was tightly linked (generally r ≥ 0.94, but 0.81 for Ce) to all others. Accumulation of REEs is negatively correlated with Ca accumulation and positively correlated with Mn and Cu accumulation in diploid Carya. In tetraploid Carya, accumulated Mg, Ca, and Fe is positively associated with foliar concentration of REEs. Total concentration of REEs in pecan's foliar ionome was 190 μg·g−1, about equivalent to that of Mn. Circumstantial evidence suggests that one or more of the physiochemically similar REEs increases physiological plasticity and subsequent adaptive fitness to certain Carya species, especially tetraploids. Because all tetraploid Carya are high REE accumulators and are native to more xeric habitats than diploids, which typically occupy mesic habitats, it appears that REEs might play a role in Carya speciation and adaptation to certain site-limiting environmental stresses. REEs appear to play an unknown metabolic/physiological role in pecan and most Carya species, especially tetraploids; thus, their nutritional physiology merits further investigation.
An assessment of vegetative traits of pecan [Carya illinoinensis (Wangenh.) K. Koch] from a range-wide provenance collection indicated the existence of at least two distinct populations within the native range (i.e., provenances north of Texas vs. provenances in Texas and Mexico). Southern most provenances generally broke bud earlier, retained foliage later in the fall, grew larger in height and trunk diameter, had narrower leaflet droop angles, had greater leaflet tilt angles, wider limb angles, greater Zn deficiency, less black pecan aphid susceptibility, and less red coloration to foliage than did northern most provenances. Trees originating from Jaumaua, in northern Mexico, were especially noteworthy insomuch that they were by far the tallest, possessed the largest trunk diameters, the longest foliation period, and lowest Zn deficiency ratings of all provenances. One family within this Jaumaua population also exhibited a high level of cold hardiness. Family heritability (hf2) estimates were ≥0.48 for trunk cross sectional area, date of budbreak, leaf redness, cold injury, leaflet droop angle, and leaflet tilt angle, and ≤0.39 for late season leaf fall, black pecan aphid susceptibility, zinc deficiency, and branch angle.
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.