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Bahman Shafii and Danny L. Barney

Trials were conducted to determine the effects of air drying and cold storage on black huckleberry (Vaccinium membranaceum Douglas ex Hooker) seeds. Treatments included fresh seeds, seeds air-dried for 7 days, and those air-dried and stored at 2 to 3 °C for either 1 or 7 years. Germination was measured every 7 days. The time course of germination was modeled using a logistic growth curve from which days to 50% germination (T50), germination rate index, and maximum germination percentages were estimated. Germination curves of dried and of dried and cold-stored seeds were significantly different from that of fresh seeds. Seeds stored for 1 or 7 years had germination percentages similar to those for the fresh, nondried seeds. Air drying for 7 days reduced the maximum germination percentage from 73% to 59% (fresh seeds). This induced dormancy was gradually lost during cold storage of dry seeds. Cold storage of air-dried seeds was an effective method for preserving V. membranaceum germplasm for at least 7 years.

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Esmaeil Fallahi, Bahar Fallahi, and Bahman Shafii

During various ages of tree between 2002 and 2007, the effects of four rootstocks and two irrigation systems using a crop evapotranspiration-based (ETc) water scheduling on water use, tree growth, yield, and fruit quality at harvest in ‘Pacific Gala’ apple [(Malus ×domestica) Borkh] were studied. The use of ETc when a precise crop coefficient value (Kc), modified by percentage of ground shade (GS) and tree canopy maturity (M) was used, provided a reliable tool for irrigation scheduling of ‘Pacific Gala’ apple. Young trees with a full sprinkler (FS) system received an average of 872.3 mm (5616.8 L/tree), whereas those with full drip (FD) received 448.9 mm (2921.1 L/tree). However, when trees were mature, trees with a FS system received an average of 994 mm (6461.7 L/tree), whereas trees with a FD received 614.1 mm (3996 L/tree) of irrigation water per growing season. Trees on ‘Budagovsky 9’ (‘B.9’) had smaller trunk cross-sectional area (TCA) and higher yield efficiency, whereas those on ‘Supporter4’ (‘Sup.4’) had larger TCA and lower yield efficiency than those on other rootstocks in all years of the study. Trees on ‘Nic.9’ (‘RN29’) always had higher yield per tree as compared with those on other rootstocks. Trees on ‘RN29’ often had higher but trees on ‘B.9’ had lower fruit weight than did those on other rootstocks. Trees on ‘Sup.4’, despite their lower yields, had smaller fruits than those on ‘RN29’ every year and thus were not suitable for planting. Fruit from trees on ‘B.9’ and ‘Cornell-Geneva30’ (‘G.30’) often had higher soluble solids concentration (SSC) and starch degradation pattern (SDP) than those other rootstocks. Fruits from trees on ‘G.30’ also had lower firmness and higher stem-end cracking, suggesting that this rootstock advances maturity in ‘Pacific Gala’ apple. Trees with FS irrigation had higher TCA than those with the FD system. Trees with the FD system were more precocious and had higher yield per tree, yield efficiency, and fruit weight than trees with the FS system when they were young. However, these differences were not significant when trees matured. ‘Pacific Gala’ fruit from trees with FS consistently had better color than those with the FD system every year. Fruits from young trees with the FD system often had higher SDP and lower firmness than those from FS irrigation.

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Danny L. Barney, Bahman Shafii, and William J. Price

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Esmaeil Fallahi, Bahar Fallahi, Bahman Shafii, and Zabihollah Zamani

‘Fuji’ apple (Malus ×domestica Borkh) has gained popularity in the past decades, but poor color of this apple mandates introduction of new strains. To pursue this objective, long-term effects of five ‘Fuji’ apple strains, consisting of ‘Autumn Rose’, ‘Desert Rose’, ‘Myra’, ‘September Wonder’, and ‘Top Export’ on RN 29 rootstock on fruit yield (in 7 years) and harvest time quality attributes (in 6 years) under climate conditions of southwest Idaho were studied during 2004–10. Fruit of ‘September Wonder Fuji’ trees were larger than those of other strains in 5 of 6 years. The type or pattern of peel color among the “low-coloring” and “high-coloring” strains varied widely. Fruits of ‘Autumn Rose Fuji’, ‘Myra Fuji’, and ‘Top Export Fuji’ always had less but ‘September Wonder Fuji’ and ‘Desert Rose Fuji’ had more red color. Fruit of ‘September Wonder Fuji’ had lower firmness but higher starch degradation pattern (SDP) than those of other strains every year as a result of the earlier maturity of this strain. Fruit of ‘Top Export Fuji’ had the lowest SDP among all strains. Fruit of ‘Autumn Rose Fuji’ tended to have lower soluble solids concentration in 3 of 6 years of this study. Considering all yield and quality attributes at harvest, ‘September Wonder’ was a great choice for an early-maturing and ‘Desert Rose’ was suitable for a late-maturing ‘Fuji’ strain. ‘Myra Fuji’ was particularly desirable for its attractive pink color that resembles bagged ‘Fuji’ without the expensive cost of labor associated with bagging.

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Esmaeil Fallahi, Bahar Fallahi, Bahman Shafii, and Mohammad E. Amiri

Production of peaches (Prunus persica) in southwestern Idaho and other states in the intermountain western United States has increased during recent years, requiring information on the performance of modern cultivars in the region. Thus, a long-term project was conducted to investigate bloom date, harvest date, cumulative growing degree-days, fruit quality, and yield of various yellow- and white-fleshed peaches under conditions of southwestern Idaho during 2003 to 2007. The analysis of average response over these years indicated that ‘Snow Giant’, ‘Jupiter’, ‘Yuko King’, ‘Burpeach Six’, ‘Fairtime’, ‘Coral Star’, ‘July Sun’, and ‘Zee Lady’ bloomed earlier (5–7 Apr.), while ‘Sierra Gem’, ‘Fancy Lady’, and ‘Red Star’ bloomed later (11–12 Apr.) than other cultivars. ‘Crimson Lady’, ‘May Sun’, and ‘Sierra Gem’ were the earliest cultivars, had smaller fruit, and on average were harvested on 11, 13, and 24 July and needed 94, 96, and 103 days from full bloom to harvest, respectively. ‘Opal Moncav’, ‘August Flame’, ‘August Lady’, ‘Ryan Sun’, ‘September Snow’, ‘Yukon King’, and ‘Fairtime’ were harvested during the second half of September. The periods between bloom and harvest for these cultivars on average were 160, 163, 163, 168, 171, 173, and 177 days, respectively, and these cultivars often had greater soluble solids concentrations than other cultivars. ‘PF12B’ and ‘PF15A’ were “mid-season,” but ‘PF 20–007’ and ‘PF 24–007’ were “late-season” cultivars. ‘PF12B’, ‘PF15A’, ‘PF 20–007’, ‘Star Fire’, ‘Burapeach Six’, ‘Coral Star’, ‘All Star’, and ‘Zee Lady’ had higher yield than many of the other cultivars. While the “early-season” cultivars can be planted for regional and local market, the “mid-season” and “late-season” peaches are excellent choices for marketing during September and early October when production of the similar cultivars are already completed in warmer regions. Overall, ‘Sweet Dream’, ‘August Lady’, ‘Zee Lady’, ‘August Flame’, ‘Snow Giant’, ‘Saturn’, ‘Jupiter’, and ‘PF24–007’ showed satisfactory to great performance in this long-term evaluation.

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Stephen L. Love, Thomas Salaiz, Bahman Shafii, William J. Price, Alvin R. Mosley, and Robert E. Thornton

Ascorbic acid (vitamin C) is an essential nutrient in the human diet and potatoes are a valuable source. As a first step in breeding for potatoes (Solanum tuberosum L.) with higher levels of ascorbic acid, 75 clones from 12 North American potato-breeding programs were evaluated for concentration, and 10 of those for stability of expression. Trials were grown in Idaho, Oregon, and Washington in 1999 and 2000, tubers sampled, and ascorbic acid quantified. There were significant differences among clones and clone by environment interaction was also significant. Concentration of ascorbic acid of the clones was continuously distributed over a range of 11.5 to 29.8 mg/100 g. A subgroup of 10 clones was analyzed using an additive main effects and multiplicative interaction (AMMI) model, to diagnose interaction patterns and measure clone stability. The first two principal component axes accounted for over 80% of the variability. Bi-plot analysis showed `Ranger Russet' to be highly unstable across the environments tested. A plot of Tai's stability statistics found six of the 10 clones to be stable for ascorbic acid expression. Appropriate evaluation methods for ascorbic acid concentration must involve multi-year testing.

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Julie M. Tarara, Paul E. Blom, Bahman Shafii, William J. Price, and Mercy A. Olmstead

Estimates of canopy and fruit fresh mass are useful for more accurate interpretation of data from the Trellis Tension Monitor, a tool for real-time monitoring of plant growth and predicting yield in trellised crops. In grapevines (Vitis labruscana Bailey), measurements of shoot and fruit fresh mass were collected at frequent intervals (14 to 21 days) over 5 years, and these data were correlated with variables that could be obtained nondestructively: shoot length, number of leaves per shoot, and number of clusters per shoot. Shoot length provided a good estimator of shoot fresh mass in all years. Nonlinear logistic regression models described the dynamics of canopy growth from bloom to the early stages of ripening, which often is poorly represented by simple linear regression approaches to seasonal data. A generalized function indicated a lower bound of ≈600 degree-days, after which an increase in shoot fresh mass could be considered on average to contribute only slightly to further increases in trellis wire tension. The dynamics of fruit mass were captured adequately by a nonlinear function, but not as well as vegetative mass because of larger variances in fruit mass. The number of clusters per shoot was associated with fruit mass only after the accumulation of ≈550 degree-days or, equivalently, the time at which fruit mass exceeded ≈25 g per shoot. Seasonal dynamics of the ratio of fruit to vegetative fresh mass were not sufficiently discernable by the logistic models because of the dominance of fruit mass and its large interannual variation.

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Esmaeil Fallahi, Bahman Shafii, Jeffrey C. Stark, Bahar Fallahi, and Saad L. Hafez

Cane growth, leaf blade area, blade and petiole fresh and dry weights and mineral nutrients of six grape (Vitis vinifera) cultivars were evaluated in 2000 and 2001 under climatic conditions of southwestern Idaho. The cultivars were: `Barbera 02', `Cabernet Sauvignon 02', `Cabernet Sauvignon 04', `Chardonnay 29', `Merlot 01', and `Sangiovese 04'. No differences were found in cane growth of different cultivars. `Sangiovese 04' and `Merlot 01' had larger leaf area and heavier leaves (both blades and petioles) and higher concentrations of blade nitrogen (N), while `Merlot 01' and `Chardonnay 29' had higher petiole nitrate-N than all other cultivars. `Merlot 01' had relatively the highest potassium (K) concentrations in both blade and petiole tissues. `Chardonnay 29' had lower concentration of calcium (Ca) and `Sangiovese 04' had lower concentrations of magnesium (Mg) in both blade and petiole tissues than other cultivars although differences were not always significant. `Barbera 02' had higher blade iron (Fe) and tended to have higher blade copper (Cu) than other cultivars. However, `Chardonnay 29' had higher petiole Fe than `Barbera 02', `Cabernet Sauvignon 04', and `Sangiovese 04'. `Merlot 01' had higher blade manganese (Mn) than `Sangiovese 04'.

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Omar A. Lopez, Danny L. Barney, Bahman Shafii, and William J. Price

Low seed germination percentages have been reported for red huckleberry (Vaccinium parvifolium Smith). Attempts to improve germination percentages and the speed of germination for red huckleberry are described. Red huckleberry seeds from two collection sites were given gibberellic acid potassium salt (GA-K) treatments (0, 500, 1000, and 1500 mg·L−1) and were germinated under three temperature regimens [constant 22 °C, 22 °C day/5 °C night (22/5 °C), and 20 °C day/13 °C night (20/13 °C) with a 12-h photoperiod]. A logistic regression model was used to assess the effects of temperature regimens and GA-K treatments on the maximum cumulative germination percentages, rates of increase, and germination lag times. For seeds untreated with GA-K, the 20/13 °C temperature regime resulted in germination percentages ranging from 30% to 61% and lag times (i.e., time to reach one-half of the maximum cumulative germination percentage) of 29 to 35 d for the two accessions. In comparison, the 22/5 °C temperature regime produced germination percentages of 12% and 38% and lag times of 38 to 64 d. The 22 °C constant temperature produced germination percentages ≤1%. Maximum germination percentages of up to 75% were obtained with 1500 mg/L GA-K. Rates of germination were generally unaffected by GA-K treatments, and germination lag times were reduced by an average of 10 d when compared with without GA-K. Improved germination percentages and reduced lag times for red huckleberry seeds were obtained by using a 20/13 °C temperature regime and 1000 to 1500 mg·L −1 GA-K.

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Esmaeil Fallahi, Denise Neilsen, Gerry H. Neilsen, Bahar Fallahi, and Bahman Shafii

Use of crop evapotranspiration (ETc), when a precise crop coefficient value (Kc) is used, provides a reliable tool (irrigation scheduling) for determination of water requirement. In this process, Kc should be modified by percentage of ground shade (GS) and tree canopy maturity (M). In an experiment in Idaho with ET-based irrigation scheduling, each tree with a full microjet sprinkler system received an average of 6461.7 L (994 mm), whereas each one with a full drip system used 3996 L (614.1 mm) of irrigation water. In general, deficit drip irrigation was shown to initially increase yield as a result of induction of stress and the production of a higher number of fruit spurs. However, production declined if the extreme water deficiency was repeatedly applied to the trees over several years. Using a microjet sprinkler system, a partial root zone drying regime reduced fruit size but slightly improved fruit color. Application of water at 65% full drip rate, applied on both sides of the tree row (DD), reduced fruit size. However, when the 65% of full drip rate was applied to only one of the alternating sides of the tree every other week (PRD), fruit size was larger than those with DD treatment.