cultivars could be evaluated in both experiments, we have presented results separately by year to illustrate the variation in potential outcomes ( Table 2 ). Table 2. Cover and cultivar effects on marketable, total (marketable + unmarketable), percent
Kaitlyn M. Orde and Rebecca Grube Sideman
Lisa Wasko DeVetter, Rebecca Harbut, and Jed Colquhoun
/or cultivar effects have been offered as an explanation for some of the differences in observed initiation dates. However, similar dates of initiation were reported in studies examining ‘McFarlin’ buds collected in British Columbia and Wisconsin despite the
Erik H. Ervin, Xunzhong Zhang, and John H. Fike
Plants possess various constitutive and inducible defense mechanisms such as pigment and antioxidant systems for protection against stresses such as ultraviolet-B (UV-B; 290 to 320 nm) radiation. Our previous research has indicated that higher chlorophyll, carotenoid, and anthocyanin concentrations were associated with greater tolerance of UV-B stress by `Georgetown' kentucky bluegrass (Poa pratensis L.). The objectives of this study were to determine if kentucky bluegrass cultivars with darker leaf color possessed greater pigment and antioxidant defense systems and if such increases were associated with greater resistance to UV-B. Eight cultivars exhibiting a range of green color intensity (`Apollo', `Brilliant', `Julius', Limerick', `Midnight', `Moonlight', `Nuglade', and `Total Eclipse') were selected and subjected to continuous, artificial UV-B radiation (70 μmol·m-2·s-1). UV-B irradiation reduced turf quality (55% to 62%) and photochemical efficiency (37% to 70%) when measured 5 days after initiation of UV-B exposure. Significant differences in turf color, photochemical efficiency, chlorophyll a, chlorophyll b, chlorophyll a+b, and carotenoids were found among the cultivars. `Moonlight' had greatest photochemical efficiency, chlorophyll, carotenoids, and turf quality. Positive correlations of pigment concentration with photochemical efficiency and turf color were observed under UV-B radiation stress, with correlation coefficients ranging from 0.49 to 0.62. The results of this study suggests that selecting cultivars with higher concentrations of chlorophyll and carotenoids and photochemical efficiency may be an effective way for turfgrass managers and sod producers to improve sod establishment and quality in environments with higher UV-B radiation.
Brian A. Kahn* and Daniel I. Leskovar
Single- and double-row arrangements of a fixed population (one plant every 0.285 m2) were compared in factorial combination with two (2002) or five (2003) cultivars for effects on yield and fruit quality of bell pepper (Capsicum annuum L.). Arrangements for 2002 were: (1) 1.9 m between centers of double-row beds, rows on beds 30 cm apart, plants within rows 30 cm apart; (2) single rows 0.95 m apart, plants within rows 30 cm apart; (3) 1.52 m between centers of double-row beds, rows on beds 24 cm apart, plants within rows 37.5 cm apart; and (4) single rows 0.76 m apart, plants within rows 37.5 cm apart. Only arrangements (1) and (2) were used in 2003. Row arrangement did not affect marketable fruit production in Oklahoma in 2002, but single rows resulted in a greater weight of fruit with blossom-end rot than double rows. Arrangement (2) resulted in both a greater weight of U.S. No. 1 fruit and a greater weight of sunburned fruit than arrangement (1) in Texas in 2002. `King Arthur' produced more marketable fruit than `X3R Wizard' in Oklahoma in 2002, but the opposite occurred in Texas. Arrangement (2) resulted in a greater weight of U.S. No. 1 fruit than arrangement (1) in both locations in 2003. Arrangement (2) also resulted in greater weights of sunburned (Oklahoma) or total cull (Texas) fruit than arrangement (1) in 2003. `Lafayette' and `X3R Wizard' produced a greater weight of marketable fruit than `Boynton Bell', `Karma', and `King Arthur' in Texas in 2003, but not in Oklahoma. Plant arrangement × cultivar interactions were not evident in Oklahoma and minimal in Texas. Given the tested population, a single row arrangement is likely to result in higher U.S. No. 1 fruit yields than a double-row arrangement, despite an increased potential for cull fruit production with single rows.
S. Alan Walters
Garlic (Allium sativum) is a popular specialty vegetable sold at many local market venues. Recently, the demand for high-quality garlic has prompted grower interest in producing this crop for direct markets. A 2-year study was conducted at the Southern Illinois University Horticulture Research Center in Carbondale to evaluate eight currently recommended garlic cultivars on a silty loam soil, as well as compare garlic produced on bare soil during the winter and wheat (Triticum aestivum) straw mulch in the spring to black plastic. ‘Idaho Silverskin’ (softneck, silverskin type) and ‘Persian Star’ (hardneck, purple-stripe type) were the best cultivars of those evaluated for the lower midwestern United States based upon various yield and quality characteristics. ‘Idaho Silverskin’ and ‘Persian Star’ had 100% winter survival (regardless of production method), high bulb quality, low amounts of foliar disease, high marketable yields with low cull production (>96% of bulblets developed marketable bulbs), and low amounts of bulb rot (<7%). Black plastic provided greater winter protection for garlic (95% survival rate) compared with bare soil (85% survival rate). Greater marketable weights and bulb diameters (50% and 23% increase, respectively) resulted when garlic was grown in black plastic compared with the bare soil/wheat straw mulch treatment.
A. A. Csizinszky
Two tomato (Lycopersicon esculentum Mill.) cvs. Agriset 761 and Equinox, were grown in spring and fall 1996 with two microirrigation rates 1x (HI) and 0.75x (LO) of the open pan evaporation and sprayed either weekly or biweekly with Anti-Stress 2000 (acrylic polymer) at 2.33 L·ha–1 in 280 to 561 L·ha–1 H2O during the first 10 weeks of the season. Tomato yields were similar with HI or LO irrigation rate and with antitranspirant sprays or water control. In both seasons, `Equinox' had a higher early but lower seasonal total marketable yield than `Agriset 761' (P ≤ 0.05). Residual soil concentrations of NO3-N and K were higher (P ≤ 0.05) with the LO, than with HI irrigation rate.
Mark K. Ehlenfeldt and Bryan T. Vinyard
A study was conducted to determine if early-fall pruning (vs. more typical winter pruning) of either northern highbush or southern highbush blueberries was detrimental to the development of optimum levels of mid-winter cold hardiness in floral buds under New Jersey conditions. Using a detached-shoot freeze-thaw assay, flower-bud LT50 values were determined in early January for both ‘Jersey’ (northern highbush) and ‘Legacy’ (southern highbush) blueberry bushes that had been subjected to early- or late-pruning protocols. Across 2 years, intrinsic differences due to genotype and genotype × year were present, but no significant differences due to pruning time were observed. The lack of pruning effects on flower-bud LT50 values suggests that cultivars with southern germplasm selected in areas such as North Carolina and further north may be treated similarly to northern highbush with respect to pruning time, including early-fall pruning.
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.
Christian A. Wyenandt, Wesley L. Kline, Daniel L. Ward, and Nancy L. Brill
From 2006 to 2008, four different production systems and five bell pepper cultivars (Capsicum annuum) with either no resistance (Alliance and Camelot), tolerance (Revolution), or resistance (Paladin and Aristotle) to the crown rot phase of phytophthora blight (Phytophthora capsici) were evaluated for the development of skin separation or “silvering” in fruit at a research facility and four commercial vegetable farms in southern New Jersey. Cultivar, production system, and year, each had a significant effect on the total percentage of fruit with skin separation and marketable yield. The percentage of bell pepper fruit with skin separation was higher in both phytophthora-resistant cultivars compared with the phytophthora-susceptible cultivars across all four production systems. Marketable yield was highest when bell peppers were grown in double rows on raised beds with black plastic mulch and drip irrigation compared with bell peppers grown on single rows on raised beds with black plastic mulch and drip irrigation and bell peppers grown on single rows on raised, bare ground beds with buried drip irrigation. Marketable yields were lowest when bell peppers were grown in single rows on high, ridged beds with overhead irrigation. Results of this study suggest that the development of skin separation or “silvering” in fruit is more closely associated with genotype than type of production system.
Hans C. Wien
Most sunflower cultivars (Helianthus annuus) grown as cut flowers produce single stems and do not form branches. If pinched (i.e., apical meristem removed) in the seedling stage, plants form branches from basal nodes. In four experiments conducted under field conditions, pinching seedlings increased the number of marketable sunflower stems per plant 2.6 to 4.6 times, but the flowers formed were reduced in diameter by 43%, and flowering was delayed by 1 week to 10 days. Leaving six instead of four basal nodes after pinching only increased stem yield slightly in 2005 but not in 2006. Increasing the space available per plant from 9 × 9 to 12 × 12 inches increased flower diameter of pinched and control plants from 7 to 7.9 cm, but the resulting lower yield per unit area reduced overall value. In three out of four experiments, ‘Procut Orange’ produced more stems after pinching than ‘Sunrich Orange’. Pinching nonbranching sunflowers is a promising technique, increasing yield by a factor of three, and the value of the harvested flowers by 82%.