James R. Ballington

Polyploidy and sexual polyploidization in the genus Vaccinium

Genus Vaccinium,consisting of blueberries, cranberries, lingonberries and many related wild species, includes diploid, tetraploid, and hexaploid species. Most evidence indicates that the tetraploid species are autotetraploids, with non-preferential bivalent chromosome pairing. Although homoploid interspecific crosses usually produce numerous fertile hybrids if the parents are from the same section of the genus, inter sectional crosses at the diploid level normally produce no seedlings, weak seedlings, or seedlings that are very low in fertility. There is a strong but not complete triploid block within Vaccinium. Even with insections, tetraploid × diploid (and the reciprocal) crosses normally give only a few tetraploid and a few triploid hybrids. Hexaploid × diploid crosses within sections are very hard to make, and the few hybrids that have been obtained are pentaploid. The frequency of 2n gametes varies,both among genotypes within species and among species. Vaccinium pollen is normally shed in tetrads, and the frequency of large pollen grains shed in dyads can be used to estimate 2n gamete frequency. Cultivated blueberries occur at both the tetraploid and the hexaploid levels, and there are important genetic resources in the diploids. Unreduced gamete production has permitted transfer of genetic material from the diploid to the tetraploid level and from the diploids and tetraploids to the hexaploid level via triploid hybrids. Intersectional crosses can occasionally produce tetraploid Vaccinium hybrids that appear to behave as amphidiploids and have medium to high fertility. CommercialVaccinium cultivars are normally propagated by cuttings. Intersectional hybridization, chromosome doubling, and asexual propagation could permit the production of novel hybrid combinations with value as ornamentals or in fruit production.

Efficient Quantification of the Health-Relevant Anthocyanin and Phenolic Acid Profiles in Commercial Cultivars and Breeding Selections of Blueberries (Vaccinium spp.)

Anthocyanins and phenolic acids are major secondary metabolites in blueberry with important implications for human health maintenance. An improved protocol was developed for the accurate, efficient, and rapid comparative screening for large blueberry sample sets. Triplicates of six commercial cultivars and four breeding selections were analyzed using the new method. The compound recoveries ranged from 94.2 to 97.5 ± 5.3% when samples were spiked with commercial standards prior to extraction. Eighteen anthocyanins and 4 phenolic acids were quantified in frozen and freeze-dried fruits. Large variations for individual and total anthocyanins, ranging from 201.4 to 402.8 mg/100 g, were assayed in frozen fruits. The total phenolic acid content ranged from 23.6 to 61.7 mg/100 g in frozen fruits. Across all genotypes, freeze-drying resulted in minor reductions in anthocyanin concentration (3.9%) compared to anthocyanins in frozen fruits. However, phenolic acids increased by an average of 1.9-fold (±0.3) in the freeze-dried fruit. Different genotypes frequently had comparable overall levels of total anthocyanins and phenolic acids, but differed dramatically in individual profiles of compounds. Three of the genotypes contained markedly higher concentrations of delphinidin 3-O-glucoside, cyanidin 3-O-glucoside, and malvidin 3-O-glucoside, which have previously been implicated as bioactive principles in this fruit. The implications of these findings for human health benefits are discussed.

Unreduced pollen frequencies versus hybrid production in diploid-tetraploid Vaccinium crosses

SummaryReciprocal crosses were made between highbush Vaccinium corymbosum L. cultivars (4X) and high, medium and low frequency diplandroid pollen producing diploid clones of V. elliotti (Chapm.) and diploid pubescent forms of V. corymbosum. Pollination of 3,342 flowers produced 15 hybrids-11 tetraploids and 4 triploids. All V. elliottii hybrids were tetraploid while each successful diploid-tetraploid V. corymbosum cross produced at least one triploid. The ratio of tetraploid hybrids to 100 pollinations (H: 100P) was considered to be the best criterion for assessing crossability. Vaccinium elliottii produced a total of 8 4X hybrids while 2X V. corymbosum only produced 3. Vaccinium elliottii was more successful as a female parent and diploid V. corymbosum only produced hybrids as male parents. High frequency diplandroid clones showed a lower mean crossability as pollen parents (H: 100P=0.2) than medium frequency diplandroid clones (H: 100P=0.8). As predicted, 0% diplandroid clones wer unsuccessful as pollen parents. Unreduced pollen production was essential for tetraploid hybrid production in 4X×2X crosses. There appeared to be no consistent, inherent pattern between 2n pollen and 2n egg production in a clone nor was a tetraploid genotype effect on crossability consistently observed.

Effect of PRE and POST Herbicides on Carolina Redroot (Lachnanthes caroliniana) Growth

Abstract Greenhouse studies were conducted in Raleigh, NC to determine Carolina redroot control by selected PRE and POST herbicides labeled for blueberries. Paraquat, glufosinate, glyphosate, and flumioxazin provided some Carolina redroot shoot control 7 d after POST application (DAPOST) ranging from 48 to 74%. Control 25 DAPOST was greatest for hexazinone at 2.2 kg ai ha−1 (90%) followed by glufosinate with 56% control and paraquat and terbacil each with 53% control. Control for most treatments declined between 25 and 63 DAPOST with the exception of glyphosate, which increased to 64%. Carolina redroot shoots per pot were reduced by terbacil, hexazinone at 2.2 kg ha−1, and glyphosate compared with the nontreated check 63 DAPOST. Control of Carolina redroot roots and rhizomes 63 DAPOST ranged from 7 to 68%, with the greatest control provided by terbacil (68%) and hexazinone at 2.2 kg ha−1 (64%). Terbacil and hexazinone at 2.2 kg ha−1 were the only treatments that reduced both shoot and root/rhizome dry weight compared with the nontreated check. Nomenclature: Flumioxazin; glufosinate; glyphosate; halosulfuron-methyl; hexazinone; paraquat, S-metolachlor; terbacil; Carolina redroot, Lachnanthes caroliniana (Lam.) Dandy. Resumen Estudios de invernadero fueron realizados en Raleigh, NC, para determinar el control de Lachnanthes caroliniana con varios herbicidas PRE y POST registrados para uso en arándanos (Vaccinum corymbosum). Paraquat, glufosinate, glyphosate y flumioxazin brindaron control parcial del tejido aéreo de L. caroliniana a 7 días después de la aplicación POST (DAPOST), el cual varió entre 48 y 74%. El mayor control a 25 DAPOST se obtuvo con hexazinone a 2.2 kg ai ha−1 (90%) seguido por glufosinate con 56% y paraquat y terbacil cada uno con 53% de control. Para la mayoría de los tratamientos, el control disminuyó entre 25 y 63 DAPOST, con la excepción de glyphosate, el cual aumentó a 64%. El número de tallos de L. caroliniana por maceta se redujo con terbacil, hexazinone a 2.2 kg ha−1, y glyphosate al compararse con el testigo no-tratado a 63 DAPOST. El control de raíces y rizomas de L. caroliniana a 63 DAPOST varió entre 7 y 68%, obteniéndose el mayor control con terbacil (68%) y hexazinone a 2.2 kg ha−1 (64%). Terbacil y hexazinone a 2.2 kg ha−1 fueron los únicos tratamientos que redujeron el peso seco de tallos y de raíces/rizomas en comparación con el testigo no-tratado.

POST Control of Carolina Redroot (Lachnanthes caroliniana)

Abstract Greenhouse studies were conducted in 2012 in Raleigh, NC to determine Carolina redroot control by ten POST herbicides. Paraquat and glufosinate provided the greatest control 14 (73 and 64%, respectively) and 25 d (82 and 68%, respectively) after treatment (DAT), but control declined between 25 and 63 DAT (72 and 59%, respectively). Glyphosate provided minimal control 14 DAT (18%), and control increased from 14 to 25 DAT (46%) and 25 to 63 DAT (69%). Control of Carolina redroot roots and rhizomes (roots/rhizomes) was greatest in plants treated with paraquat (91%), glyphosate (88%), glufosinate (73%), hexazinone (62%), diuron (60%). Nontreated Carolina redroot shoot and root/rhizome dry weight were 8.3 and 7.6 g, respectively. Paraquat, glufosinate, glyphosate, and diuron reduced both shoot and root/rhizome dry weight (3.1 and 0.7 g, 5.1 and 2.7 g, 5.4 and 1.0, 5.7 and 1.6 g, respectively). Hexazinone reduced root/rhizome dry weight (2.7 g). Fomesafen reduced shoot dry weight (6.1 g), but did not reduce root/rhizome dry weight. Paraquat, glufosinate, glyphosate, hexazinone, diuron, and clopyralid treatments resulted in reduced incidence of Carolina redroot flowering and anthesis. Nomenclature: Clopyralid; diuron; flumioxazin; fomesafen; glufosinate; glyphosate; halosulfuron-methyl; hexazinone; paraquat; sethoxydim; Carolina redroot, Lachnanthes caroliniana (Lam.) Dandy. Resumen En 2012, se realizaron estudios de invernadero en Raleigh, NC para determinar el control de Lachnanthes caroliniana con diez herbicidas POST. Paraquat y glufosinate brindaron el mayor control 14 d (73 y 64%, respectivamente) y 25 d (82 y 68%, respectivamente) después del tratamiento (DAT), pero el control disminuyó entre 25 y 63 DAT (72 y 59%, respectivamente). Glyphosate brindó un control mínimo 14 DAT (18%), y el control incrementó de 14 a 25 DAT (46%) y 25 a 63 DAT (69%). El control de las raíces y rizomas (raíces/rizomas) de L. caroliniana fue mayor en plantas tratadas con paraquat (91%), glyphosate (88%), glufosinate (73%), hexazinone (62%), diuron (60%). El peso seco del tejido aéreo y raíces/rizomas de L. caroliniana sin tratar fue 8.3 y 7.6 g, respectivamente. Paraquat, glufosinate, glyphosate, y diuron redujeron el peso seco del tejido aéreo y raíces/rizomas (3.1 y 0.7 g, 5.1 y 2.7, 5.4 y 1.0, 5.7 y 1.6 g, respectivamente). Hexazinone redujo el peso seco de raíces/rizomas (2.7 g). Fomesafen redujo el peso seco del tejido aéreo (6.1 g), pero no redujo el peso seco de raíces/rizomas. Los tratamientos con paraquat, glufosinate, glyphosate, hexazinone, diuron, y clopyralid resultaron en una incidencia reducida de floración y antesis de L. caroliniana.

Weed Control in Southern Highbush Blueberry with S-metolachlor, Flumioxazin, and Hexazinone

Abstract Field studies were conducted in 2010, 2011, and 2012 at a commercial blueberry farm near Burgaw, NC to determine weed control and crop tolerance to S-metolachlor and flumioxazin alone or mixed with hexazinone. Herbicides were applied pre-budbreak and postharvest. Pre-budbreak applications consisted of hexazinone at 1.1 or 2.2 kg ai ha−1, S-metolachlor at 1.4 or 2.8 kg ai ha–1, and flumioxazin at 215 g ai ha–1 alone and tank mixes of hexazinone or flumioxazin plus S-metolachlor. Additional treatments consisted of flumioxazin (215 g ha–1), flumioxazin plus S-metolachlor (1.4 and 2.8 kg ha–1), or hexazinone (1.1 kg ha–1) plus S-metolachlor (1.4 and 2.8 kg ha–1) applied pre-budbreak and followed by (fb) a postharvest application of flumioxazin (215 g ha–1). Herbicide programs containing flumioxazin resulted in greater Maryland meadowbeauty control (73%) 5 to 6 weeks after treatment (WAT) than herbicide programs containing hexazinone at 1.1 or 2.2 kg ha–1 (37% and 39%, respectively). Needleleaf rosette grass control remained ≥94% for all herbicide programs through 2 WAT. Hexazinone at 1.1 kg ha–1 provided greater needleleaf rosette grass control (87%) than flumioxazin (71%) 5 to 6 WAT. Meadowbeauty and needleleaf rosette grass control by all herbicide programs was poor (≤39% and ≤57%, respectively) 16 to 18 WAT. Two weeks after post-harvest applications, herbicide programs receiving a post-harvest flumioxazin application had greater meadowbeauty and needleleaf rosette grass control (78% and 84%, respectively) than those programs without a post-harvest flumioxazin application (43% and 71%, respectively).