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Anita Solar, Robert Veberic, and Franci Stampar

‘Sava’ and ‘Krka’ are new walnut cultivars of Slovene origin. They were developed and evaluated at the Biotechnical Faculty Ljubljana, Slovenia, and were released in 2013. ‘Sava’ is a late-leafing cultivar, appropriate for orchard planting in

Open access

Gary A. Couvillon, Nelson Finardi, Marcio Magnani, and Claudio Freire

Abstract

The rootstock has been shown to influence the chilling requirement of pear (Oregon) (9) and peach (New Jersey) (10). This is not surprising because the rest influence moves across graft unions (1) and the scion and stock differ genetically and may have different chilling requirements. However, it has been reported that under the chilling conditions characteristic of the major California pear districts, rootstock had little or no influence on bloom date or chilling requirement (5). Also, budbreak and/or bloom of ‘Croncels’ (3), ‘Delicious’, and ‘McIntosh’ (4) were not influenced by early and late leafing stocks.

Open access

D. E. Kester, Paolo Raddi, and R. Asay

Abstract

Relationships among blooming and leafing dates of parents, offspring, and the chilling requirements of the intervening seed were determined among a group of families of almond (Prunus amygdalus Batsch). Parentoffspring heritabilities for blooming and leafing dates were high. Leafing and blooming dates of individuals and families, although significantly correlated, were more or less independent traits. Seed chilling was a function of both seed and pollen parents and was correlated with mean bloom and leafing of parents. The correlation coefficient between chilling of a seed and the blooming date of the corresponding offspring plant was significant and large when calculated for families and significant, but low, when calculated for individuals. The seed-leafing correlation was significant when the early and late leafing progeny were considered separately.

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Otto L. Jahn and Malcolm N. Dana

Abstract

Correlation and regression analyses were made on growth measurements obtained from ‘Dunlap,’ ‘Sparkle’ and ‘Catskill’ strawberry plants grown in the greenhouse. Two tests were evaluated in which plants of 3 and 7 age groups and a range of weights were included. Results indicated close relationships between many growth measurements. These included high correlations between initial plant weight and plant age, leaf production rate, and early leaf area. After 3 or 4 months, growth correlations of .5 to .8 were still present between initial plant weight and leaf area and between early and late leaf area measurements. Correlations of .3 to .8 were found between initial weight or plant age and the number of flower buds. Correlations were generally similar in all cultivars and for both tests. The results indicate that some of these measurements could be used to predict or evaluate growth response of strawberry plants to applied treatments.

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Shawn A. Mehlenbacher and Anna M. Voordeckers

The relationship between dormancy of seeds and buds of apple (Malus × domestica Borkh.) might provide breeders with an early opportunity to select for delayed development. Seeds of late-flowering genotypes require much longer exposure to chilling temperatures than those of early flowering” genotypes, and they germinate over a much longer period. In three progenies that exhibit much variation for the two traits, seed germination time was correlated with time of leafing-out of the resulting seedlings, and could be used to select for delayed budbreak. However, selection would be ineffective when little genetic variation for seed germination and budbreak is present. Leafing-out ratings in the nursery in the 2nd year were highly correlated with those in the 3rd year, indicating that selection for late leafing in the nursery during the 2nd year would be more effective than selection based on seed dormancy, especially in progenies exhibiting little genetic variability for this trait. Breeders can effectively use both relationships by first eliminating early germinating seeds and then eliminating early leafing seedlings.

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Aparna Gazula, Matthew D. Kleinhenz, John G. Streeter, and A. Raymond Miller

Pigment concentrations in leaf tissue affect the visual and nutritional value-based indices of lettuce crop quality. To better discern the independent and interactive effects of temperature and cultivar on anthocyanin and chlorophyll b concentrations, three closely related Lolla Rosso lettuce cultivars (`Lotto', `Valeria', and `Impuls'), varying primarily in the number of genes controlling anthocyanin concentrations, were subjected to different air temperatures in controlled environments. Fifteen-day-old seedlings previously grown at 20 °C day/night (D/N) were transplanted into growth chambers maintained at 20 °C (D/N), 30/20 °C D/N and 30 °C D/N air temperatures. Twenty days later, leaf tissue was sampled for measures of pigment concentrations, calculated based on spectrophotometric absorbance readings taken at 530 nm (anthocyanin) and 660 nm (chlorophyll b) respectively. Although significant, the temperature × cultivar interaction resulted from differences in the magnitude (not direction) of the change in pigment concentrations among cultivars with changes in temperature. Regardless of cultivar, anthocyanin and chlorophyll b concentrations were highest, moderate and lowest after growth at 20 °C D/N, 30/20 °C D/N and 30 °C D/N respectively. Likewise, irrespective of temperature, anthocyanin and chlorophyll b concentrations followed the pattern `Impuls' (three genes) > `Valeria' (two genes) > `Lotto' (one gene). These data provide additional strong evidence that lettuce leaf pigment concentrations and growing temperatures are negatively related. The data also suggest that low temperatures during the dark phase may mitigate high temperature-driven reductions in lettuce leaf pigment levels.

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J. Rodriguez-A., W.B. Sherman, R. Scorza, M. Wisniewski, and W.R. Okie

The evergreen (EVG) peach, first described in Mexico, was used as a parent with deciduous (DE) peaches to develop F1 and F2 hybrid populations in Mexico, Florida, Georgia, and West Virginia. F1 trees were DE and F2 plants segregated 3 DE: 1 EVG. In West Virginia, the most temperate location, the heterozygous class could be distinguished in the first few years of growth by late leaf abscission in the fall. Segregation ratios suggest that the EVG trait is controlled by a single gene, evg, the EVG state being homozygous recessive. Evergreen trees were characterized by insensitivity of shoot tips to daylength and failure of terminal growth to cease growth until killed by low temperature. Lateral buds of EVG trees went dormant in the fall. Deep supercooling occurred in both EVG and DE trees, but it appeared later in EVG trees, was of shorter duration, and occurred to a lesser extent. Evergreen germplasm may be useful in developing peach cultivars for frost-free subtropic and tropical areas. It also presents a useful system for studying dormancy and cold hardiness.

Open access

Darab Hassani, Mohammad Reza Mozaffari, Asghar Soleimani, Raana Dastjerdi, Reza Rezaee, Mansureh Keshavarzi, Kourosh Vahdati, Ahmad Fahadan, and Jamal Atefi

, Jamal and Damavand, were released in 2010 ( Hassani et al., 2012a , 2012b ). The second phase of this program, with the aim of selecting for late leafing and lateral-bearing cultivars, was carried out during early 2000. A total of 39 promising walnut

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Saadat Sarikhani Khorami, Kazem Arzani, Ghasem Karimzadeh, Abdolali Shojaeiyan, and Wilco Ligterink

considered as a useful tool to study walnut germplasm ( Arzani et al., 2008 ). The results showed that FaBaAg1 (25 DARS) and FaBaAv2 (21 DARS) were late-leafing and midseason ripening genotypes ( Table 2 ). In terms of harvesting date, all studied genotypes

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Mehmet Sütyemez, Şakir B. Bükücü, and Akide Özcan

walnut breeding programs in many countries are to provide late-leafing cultivars with a high yield and a resistance to biotic and abiotic stresses. However, there has been a limited number of studies on the cluster-bearing habit in walnuts ( Germain et al