Search Results

You are looking at 111 - 120 of 4,602 items for :

  • "selection" x
  • Refine by Access: All x
Clear All
Free access

John C. Pair, Channa Rajashekar, and Michael Shelton

Numerous cultivars of lacebark elm (Ulmus parvifolia) have been introduced recently without adequate testing of their hardiness. A block of commercial cultivars plus numerous experimental numbers were established to observe differences in growth form, ornamental characteristics, and cold hardiness. Laboratory freezing tests were conducted from November to March over a 3-year period to determine acclimation and deacclimation to low temperatures. Stem sections approximately 5 cm long were sealed in test tubes and placed in a low-temperature programmable freezer maintained at 0°C. Samples were cooled by approximately 6°C per hour from 0 to –48°C and held for 1 h at each temperature. Samples were then removed, allowed to thaw at room temperature, and held for 7 to 10 days. Stem samples were sectioned longitudinally to observe browning in xylem and bark tissues. During the winter of 1995–96, no visible injury could be noted on trees in the field in spite of very dry, desiccating weather with temperatures reaching –23°C. Laboratory freezing tests indicated acclimation to –30°C by 18 Dec. 1995 on several cultivars. During warm periods in February, deacclimation occurred on many selections to –18°C, whereas others maintained a killing point of –30°C. Growth form, bark exfoliation, and fall color varied among cultivars.

Free access

R. Bruce Carle and J. Brent Loy

Three experiments were conducted to delineate gametophytic selection of the fused vein trait in Cucurbita pepo L. Gametophytic subvitality was verified by comparing fused vein and normal pollen tube growth. Microscopic examination of partitioned, co-pollinated flowers revealed fewer and slower growing fused vein tubes than normal. The effects of gametophytic subvitality on seed yield and inheritance were shown by manipulating the severity of reproductive competition. Fused vein, normal, and F1 lines were pollinated with fused vein, normal, 50:50 mix, and F1 pollen at three different pollen loads. Analysis showed that fused vein pollen generated significantly fewer seed per fruit in all lines. In ensuing F2 and testcross populations, a reduction in load and thus competition significantly increased the number of fused vein individuals. Leaf number and area for normal, fused vein, F1, F2, and testcross plants were assessed to test pleiotropic effects on growth common to gametophytic subvitals. Although normal and fused vein lines differed in leaf number and size, their total leaf areas were not significantly different. F2 and testcross plants showed no difference between normal and fused vein individuals; leaf size and number were independent of leaf morphology.

Open access

Glenn M. Ito and Janies L. Brewbaker

Abstract

In the paper “Genetic Advance through Mass Selection for Tenderness in Sweet Corn” by Glenn M. Ito and James L. Brewbaker (J. Amer. Soc. Hort. Sci. 106(4):496-499.1981) there are errors in the numbering of and textual references to the figures and tables. Table 1 on page 497 should be labeled Table 4, Table 2 on page 497 should be labeled Table 1, Table 3 on page 498 should be labeled Table 2, and Table 4 on page 499 should be labeled Table 3. Figure 1 on page 497 should be labeled Figure 3, Figure 2 on page 498 should be labeled Figure 1, and Figure 3 on page 498 should be labeled Figure 2. Accordingly, line 7 of the section beginning “Correlation of bite-test scores and pericarp thickness measurements” on page 498 should refer to Table 4; the last line on page 498 should refer to Figure 3; and line 8 of the first paragraph, second column, of page 499 should refer to Table 2. All other textual references correspond to the correct table and figure numbers as presented above.

Free access

Neil O. Anderson and Peter D. Ascher

Commercial garden and greenhouse chrysanthemums [Dendranthema ×grandiflora (Ramat.) Kitam. (syn. Chrysanthemum xmorifolium Ramat.)] are facultative short-day plants for flower bud initiation, obligate short-day plants for flower bud development, and are categorized into short-day response groups. Flower initiation can be delayed by high night temperatures. Recent research has identified true day-neutral genotypes. The purpose of this investigation was to test environments for selecting genotypes that are both day-neutral and heat-delay insensitive. One greenhouse and 18 garden genotypes were selected. A series of environments were used to select for day-neutral genotypes and then differentiate between these genotypes for heat delay insensitivity: short days, long days/red light, long days/far red light and high temperatures, and natural day lengths under field conditions. Day-neutral selections from these environments were then grown in a fifth environment of long days/continuous far red and red light with high temperature. Data were collected on the number of days to first and third flower, long day leaf number, stem length, number of strap-shaped leaves subtending the terminal flower, internode lengths, number of nodes with axillary branching, and flower bud development of the first to the sixth flowers. Genotypes required 3 to 8 weeks for complete flower bud initiation/development. Flowering responses in the first four environments were highly significant for both the first and third flowers. Genotypes ranged from obligate short-day to day-neutral for the first six flowers. Three day-neutral genotypes were selected that differed significantly for all traits in the fifth environment; flower bud development with the first six flowers occurred with only one genotype, 83-267-3. Broad sense heritability estimates ranged from h2 = 0.75 for number of nodes with axillary branching, h2 = 0.79 for long day leaf number and number of strap-shaped leaves, to h2 = 0.91 for stem length. An ideotype for day-neutral and heat-delay-insensitive garden chrysanthemums was developed for use in breeding programs.

Free access

Tao Wang, Ruijie Hao, Huitang Pan, Tangren Cheng, and Qixiang Zhang

, China) according to the manufacturer’s instructions. The cDNAs were diluted 1:10 with nuclease-free water before qRT-PCR analyses. Selection of potential reference genes. The 10 candidate genes evaluated in this experiment were based on the mei

Open access

Géza Bujdosó, Sezai Ercisli, Alina Ratiu, and Klara Cseke

base for selection from the local population ( Iordănescu et al., 2021 ; Trandafir and Cosmulescu, 2020 ). Walnut production in Hungary started with the planting of seedlings of French-bred varieties at the beginning of 20th century. As a result of

Open access

Job Teixeira de Oliveira, Rubens Alves de Oliveira, Priscilla Andrade Silva, and Paulo Eduardo Teodoro

appropriate selection ( Belay, 2018 ). Path coefficient analysis, or path analysis, has been widely used to understand production better and to determine the nature of the relationships between fruit and their constituent components, and to identify those

Free access

Hassan Hajnajari, Bahaeddin Chashnidel, Kourosh Vahdati, Mohsen Ebrahimi, Alireza Nabipour, and Esmaeil Fallahi

traits for progeny selection in the breeding program demands genetic studies to distinguish the environmental and the genetic variances from the phenotypic variances, to calculate the expected genetic contribution in the form of heritability, and to

Free access

William S. Castle, James C. Baldwin, Ronald P. Muraro, and Ramon Littell

gathered from those combined sources is assembled into summary charts that are used as a guide for rootstock selection ( Castle et al., 1993 , 2006 ; Ferguson et al., 1990 ; Newcomb, 1978 ). It is uncommon that additional or better selection criteria

Free access

Ryan J. Hayes, Karunakaran Maruthachalam, Gary E. Vallad, Steven J. Klosterman, and Krishna V. Subbarao

section was interpreted as a positive result (infected) for that plant. Accessions evaluated. Selection for Verticillium wilt resistance was conducted in two independent populations of accessions (Populations A and B) ( Table 1 ). Each population was