Cycles Of Phenotypic Recurrent Selection Research Articles

Registration of ‘Espresso’ lowland switchgrass

Abstract‘Espresso’ (Reg. no. CV‐293, PI 687202) is a lowland ecotype (Gulf sub‐population) of switchgrass (Panicum virgatum L.) developed and released by Mississippi State University and the Mississippi Agricultural and Forestry Experiment Station. Espresso was developed from seven cycles of phenotypic recurrent selection for rapid seed germination without stratification. All cycles of selection were made using seed harvested from open‐pollinated isolation blocks containing approximately 100 mother plants. Germination was assessed in laboratory conditions for 15 years, culminating in 2 years of field‐based germination and emergence evaluation at five locations across Mississippi. Over a 2‐year period, germination and emergence of Espresso was significantly greater (P < 0.05) than seed from ‘Alamo’ and ‘Kanlow’. Field testing revealed Espresso as having significantly (P < 0.05) greater establishment success (mean number of seedlings per linear 30 cm) when compared to Alamo. Espresso was released based on the need for southeastern US‐adapted germplasm that possesses enhanced germination characteristics.

TX‐BHS berseem clover germplasm

AbstractTX‐BHS (Reg. no. GP‐312, PI 699627) is a germplasm line of berseem clover (Trifolium alexandrinum L.) selected for increased cold tolerance and hard seed production. This germplasm line was developed by Texas A&M AgriLife Research at Overton and is intended to extend the range and utility of this annual clover species. Berseem is well adapted to wet and waterlogged soils and has potential for expanded use in both pasture and cover crop systems. Improved hard seed production would allow expanded use of berseem in reseeding pasture and cropping systems. Three cycles of recurrent half‐sib selection and two cycles of recurrent phenotypic selection were applied to the variable base population (Mississippi Winter Hardy Berseem) at Overton, TX, from 1982 to 1988. Selection was successful in improving hard seed levels of TX‐BHS relative to ‘Bigbee’ berseem. Selection for winter survival and reduced cold damage caused a reduction in winter growth of TX‐BHS berseem relative to Bigbee berseem. This growth pattern shift was only observed in only one trial. The actual impact of selection on winter survival and cold tolerance of TX‐BHS berseem needs further study.

Improving Fusarium Basal Rot Resistance of Onion Cultivars through Artificial Inoculation and Selection of Mature Bulbs

Fusarium basal rot (FBR) of onion, caused by the soil-borne fungus Fusarium oxysporum f.sp. cepae (FOC), results in a substantial storage loss of marketable bulbs. Seedling and field screening methods, which were used to generate FBR resistant long-day and intermediate-day onion cultivars, were found to be ineffective at increasing FBR resistance in short-day onion cultivars. This study attempted to improve the FBR resistance of seven commercial short-day onion cultivars and two check cultivars when evaluated at their mature bulb stage. Mature bulbs were artificially inoculated with 1 cm diameter potato dextrose agar plugs containing conidia of a virulent FOC isolate, CSC-515, at a concentration of 3 × 104 spore mL−1, after transversely cutting the basal plate tissue. Incubated bulbs, which had few or no FBR symptoms, were selected after 20 d using visual scoring, from 1 (no disease) to 9 (>70% basal plate is infected), and combined in seed production cages to produce the selected generation of a cultivar. Multiple cycles of phenotypic recurrent selection were conducted, and the resultant populations were compared with their respective original populations for FBR severity and incidence, from 2016 to 2019, using the same conidial inoculation method. A variable amount of progress was achieved in reducing FBR severity and incidence in the seven cultivars, with maximum improvement in the most advanced selected populations. FBR development in the advanced selected populations differed between mature bulbs of each entry and was influenced by yearly environmental variation. The progress of FOC infections was slower in resistant bulbs when compared to susceptible bulbs. These results indicated a partial or quantitative resistance against FBR. The partial FBR resistant cultivar populations could be used to develop synthetic short-day FBR resistant cultivars after multi-locational and multi-seasonal field trials. These populations could also be used to study the mechanism(s) of FBR resistance in onion, which has yet to be determined.

Recurrent phenotypic selection for resistance to diseases caused by Bipolaris oryzae in switchgrass (Panicum virgatum L.)

Switchgrass (Panicum virgatum L.) is a biomass candidate crop which has been improved for yield, but disease resistance development has largely been ignored. Bipolaris oryzae (Breda de Haan) Shoemaker can cause Bipolaris seed rot, reducing seedling establishment, and Bipolaris leaf spot, reducing biomass yield. In order to initiate a breeding program, heritability based on half-sib progenies of the disease resistance were conducted in 47 half-sib progenies of lowland ‘Kanlow’ and upland ‘Cave-in-Rock’. Test crosses of progenies from resistant and susceptible parents in upland ‘Shelter’ and Cave-in-Rock were conducted to determine genetic control of resistance to Bipolaris leaf spot. To breed for resistance to two diseases, two cycles of recurrent phenotypic selection were done separately in Shelter and Cave-in-Rock at 10% selection intensity. As a result, resistance to Bipolaris seed rot showed moderate to high heritability (0.33 ± 0.16 to 0.83 ± 0.09) in both individual- and half-sib-based computations, reflecting actual genetic gain (44.5–125.3%) from two cycles of selections. However, resistance to Bipolaris leaf spot showed non-significant heritability (0.02 ± 0.06 to 0.19 ± 0.19) and non-significant progress of selection for the trait. Results from test crosses suggested that the resistance was not controlled by R genes but possibly was quantitatively inherited by many alleles with small effects. Such a difference in the gains resulted in non-significant correlation between two resistances. Due to high progress in selection resistance to Bipolaris seed rot, the screening method for resistance can be integrated to existing breeding programs.

Selection Mapping Identifies Loci Underpinning Autumn Dormancy in Alfalfa (Medicago sativa).

Autumn dormancy in alfalfa (Medicago sativa) is associated with agronomically important traits including regrowth rate, maturity, and winter survival. Historical recurrent selection experiments have been able to manipulate the dormancy response. We hypothesized that artificial selection for dormancy phenotypes in these experiments had altered allele frequencies of dormancy-related genes. Here, we follow this hypothesis and analyze allele frequency changes using genome-wide polymorphisms in the pre- and postselection populations from one historical selection experiment. We screened the nondormant cultivar CUF 101 and populations developed by three cycles of recurrent phenotypic selection for taller and shorter plants in autumn with markers derived from genotyping-by-sequencing (GBS). We validated the robustness of our GBS-derived allele frequency estimates using an empirical approach. Our results suggest that selection mapping is a powerful means of identifying genomic regions associated with traits, and that it can be exploited to provide regions on which to focus further mapping and cloning projects.

Molecular characterization of two cycles of phenotypic recurrent selection in globe artichokes using microsatellite and SRAPs markers

Molecular characterization of two cycles of phenotypic recurrent selection in globe artichokes using microsatellite and SRAPs markers

Rapid development of a castor cultivar with increased oil content

Castor seed oil contains 90% ricinoleic acid which has a wide range of industrial applications. Improvement in oil content would be of great benefit to castor growers and oil processers. Two cycles of phenotypic recurrent selection were conducted through screening for high oil content castor seeds using magnetic resonance spectroscopy (NMR). Selection increased mean oil content of a base population (Cycle 0) of cultivar Impala from 50.33% to 53.87% in Cycle 1 and 54.47% in Cycle 2. Gains from Cycle 1 and Cycle 2 were 3.54% and 0.6%, respectively. The small gain in the second cycle indicated a genetic ceiling of oil content or the genetic variability of the base population was extensively explored. Nevertheless, the 54.47% mean oil content of Cycle 2 ranks the selected material in the top 1% of the entire 1103 castor accessions maintained at United States of Department of Agriculture. As a result of the recurrent selection, we found average seed weight was also increased from 0.44g in Cycle 0 to 0.50g in Cycle 1 and 0.54g in Cycle 2. Correlation between oil content and weight was moderate (r=0.43, p<0.0001) in Cycle 0, and strong in Cycle 1 (r=0.63, p<0.0001) and Cycle 2 (r=0.77, p<0.0001). To our knowledge, this is the first report of utilizing NMR and recurrent selection for improving oil content in castor.

A proteome analysis of freezing tolerance in red clover (Trifolium pratense L.).

BackgroundImprovement of freezing tolerance of red clover (Trifolium pratense L.) would increase its persistence under cold climate. In this study, we assessed the freezing tolerance and compared the proteome composition of non-acclimated and cold-acclimated plants of two initial cultivars of red clover: Endure (E-TF0) and Christie (C-TF0) and of populations issued from these cultivars after three (TF3) and four (TF4) cycles of phenotypic recurrent selection for superior freezing tolerance. Through this approach, we wanted to identify proteins that are associated with the improvement of freezing tolerance in red clover.ResultsFreezing tolerance expressed as the lethal temperature for 50 % of the plants (LT50) increased markedly from approximately −2 to −16 °C following cold acclimation. Recurrent selection allowed a significant 2 to 3 °C increase of the LT50 after four cycles of recurrent selection. Two-dimensional difference gel electrophoresis (2D-DIGE) was used to study variations in protein abundance. Principal component analysis based on 2D-DIGE revealed that the largest variability in the protein data set was attributable to the cold acclimation treatment and that the two genetic backgrounds had differential protein composition in the acclimated state only. Vegetative storage proteins (VSP), which are essential nitrogen reserves for plant regrowth, and dehydrins were among the most striking changes in proteome composition of cold acclimated crowns of red clovers. A subset of proteins varied in abundance in response to selection including a dehydrin that increased in abundance in TF3 and TF4 populations as compared to TF0 in the Endure background.ConclusionRecurrent selection performed indoor is an effective approach to improve the freezing tolerance of red clover. Significant improvement of freezing tolerance by recurrent selection was associated with differential accumulation of a small number of cold-regulated proteins that may play an important role in the determination of the level of freezing tolerance.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0751-2) contains supplementary material, which is available to authorized users.

Estimate of genetic gain in popcorn after cycles of phenotypic recurrent selection

Popcorn is widely consumed in Brazil, yet there are few breeding programs for this crop. Recurrent selection (RS) is a viable breeding alternative for popcorn; however, the gains achieved must be frequently checked. The aim of this study was to assess the effect of selection for grain type (round and pointed) after four cycles of phenotypic RS on the main agronomic traits of popcorn, to estimate the genetic gain achieved for the trait of expansion volume (EV), and to obtain estimates of phenotypic correlations for the main traits of the crop in the UFLA E and UFLA R populations. The zero, one, two, and three cycles of the UFLA E and UFLA R populations, the fourth cycle, and the controls IAC-112 and IAC-125 were used. The experiments were conducted at the experimental farm of Universidade Federal de Lavras (UFLA; Environment 1) and at the experimental area of the Genetics and Plant Breeding Sector of the Department of Biology at UFLA (Environment 2) in the 2010/11 crop season. Nine agronomic traits were evaluated, including EV and grain yield (GY). The UFLA R and UFLA E populations showed similar behavior for all evaluated traits. The type of grain did not affect the genetic gain for EV, which was 5 and 3.7% in each cycle carried out in the UFLA E and UFLA R population, respectively. Phenotypic selection carried out during recombination for EV is an effective method for increasing expression of the trait. EV and GY did not show a linear association.

Behavior of half-sib progenies of coriander

This work evaluated the behavior of coriander half-sib progenies ( Coriandrum sativum L.) regarding their agronomic traits. The study was developed in a greenhouse in the Universidade Federal Rural de Pernambuco, PE, Brazil. The experiment was designed as augmented block design with 26 coriander genotypes, of which 24 were coriander half-sib treatments, and two control treatments, ‘Verdao’ and ‘Tabocas’. These progenies were selected from four cycles of phenotypic recurrent selection from the ‘Verdao’ population, which were selected for later bolting. Plant height and canopy diameter were evaluated in the field, and shoot fresh mass. There were significant differences between the treatment means for all variables analyzed. Regarding analysis of variance and SNK test, there is available variability to select half-sib progenies. Genotypes C 4 -014, C 4 -015, C 4 -016, and C 4 -018 had promising productivity compared to the commercial control varieties. The broad-sense heritability values were 77.3, 81.5 and 95.8% for canopy diameter, shoot fresh mass, and plant height, respectively. This result showed that the majority of phenotypic variance is genetic. Therefore, these genotypes may be used in coriander breeding programs of recurrent selection to obtain cultivars adapted to tropical conditions.

Selection by seed weight improves traits related to seedling establishment in Panicum coloratum L. var. makarikariense

AbstractSelection for heavy seed was implemented to overcome establishment problems in Panicum coloratum var. makarikariense. A collection covering the genetic diversity of the species available in Argentina was used as a base population (BP), and two cycles of recurrent phenotypic selection to increase seed weight were performed. Seedlings, obtained from seeds from each cycle and the BP, were further evaluated in the greenhouse. An increase of 17% in mean seed weight was obtained after two cycles of recurrent selection. No differences in germination or emergence were detected among the selected materials and the BP. However, seedlings from selected materials were taller and showed higher leaf elongation rate, adventitious roots elongation rate and total growth rate than that from BP. This research also revealed that in P. coloratum var. makarikariense, more vigorous seedlings can be selected from genotypes that produce heavier seeds.

Registration of Two Improved Yellow‐Flowered Alfalfa Germplasms

Journal of Plant Registrations, Vol. 1, No. 2, September 2007 131 IAMF101 and IAMF102, yellow-fl owered alfalfa [Medicago sativa subsp. falcata (L.) Arcang.] populations, were developed by the Raymond F. Baker Center for Plant Breeding at Iowa State University, Ames, IA and the U.S. Dairy Forage Research Center (USDA-ARS), Madison, WI. These populations were released by the Iowa State University Research Foundation in September 2006. IAMF101 is designated as Reg. No. GP-347 PI 643446 and IAMF102 is designated as Reg. No. GP-348 PI 643447 in the national plant germplasm system (NPGS). IAMF101 is a genetically broad based tetraploid (2n = 4x = 32) Medicago sativa subsp. falcata germplasm, and has pods that range from M. falcata (sickle-shaped) (~70%) to single coiled. IAMF101 was developed by two cycles of recurrent phenotypic selection for persistence, autumn regrowth, and vigor from a broad based, yellow-fl owered alfalfa germplasm collection. It was previously known by the name “IAFAL.” The parent plants were selected on 22 Sept. 1999 from a germplasm evaluation trial at the Iowa State University Agronomy and Agricultural Engineering Farm near Ames, IA that had been planted in spring 1997. Selection was based on yield performance, freedom from disease and insect pests, and autumn regrowth. The 36 selected parents of IAMF101 derived from the following sources (number of plants in parentheses): IA-3018 (Kehr, 1973) (3), PI 314092 (2), PI 315476 (2), PI 384507 (4), PI 494661 (2), PI 502441 (2), PI 502450 (2), PI 502453 (3), PI 505872 (1), PI 538985 (1), PI 538989 (1), PI 538993 (1), PI 538994 (2), PI 573175 (1), PI 631597 (4), PI 631806 (2), WISFAL (Bingham, 1993) (3). The experimental yellow-fl owered alfalfa population IA-3018 is an 11-clone synthetic of diverse origin developed at Iowa State University by C.P. Wilsie in the 1960s (Kehr, 1973). Parental plants were intercrossed by hand in the greenhouse at Ames, IA during the winter of 1999–2000 and equal quantities of seeds from each parent were bulked. Seeds were germinated in spring 2000 in the greenhouse, and approximately 1000 Registration of Two Improved Yellow-Flowered Alfalfa Germplasms

Response of a Maize Synthetic to Selection for Components of Partial Resistance to Exserohilum turcicum.

A synthetic population of maize (Zea mays) was created from five inbred lines of varying levels of partial resistance to northern leaf blight (NLB). This synthetic was subjected to three cycles of recurrent phenotypic selection with pollen control for either increased latent period or decreased lesion length. A selection intensity of ca. 10% was used in each selection cycle. The original synthetic and three advanced selection cycles for each of the two components of partial resistance were evaluated in field trials in the summers of 1999 and 2001, and in greenhouse trials. Selection for increased latent period was more effective in improving resistance to NLB (20 to 27% gain/cycle) (as measured by area under the disease progress curve [AUDPC]) than was selection for decreased lesion length (14 to 18% gain/cycle). Responses in AUDPC to selection for either component of resistance were linear in the 1999 field trial, but were quadratic (decreased response in advanced cycles) in the 2001 trial. Selection for increased latent period in the field resulted in a 0.6-day increase in latent period per selection cycle when measured in the greenhouse and a 2-day increase per selection cycle when measured in the field. Selection for decreased lesion length in the field did not significantly alter latent period in the greenhouse. These results support using selection for increased latent period as an effective means of improving partial resistance to NLB in maize populations. Decreased lesion length was more difficult to measure and selection based on this criterion was less effective in improving partial resistance.

Increased Glyphosate Tolerance in ‘Aurora Gold’ Hard Fescue (Festuca longifolia)

Studies were conducted in New Jersey and Virginia to evaluate the response of ‘Aurora Gold’ hard fescue, which had undergone five cycles of phenotypic recurrent selection for increased glyphosate tolerance, to direct applications of glyphosate. ‘Discovery’ hard fescue, which had not undergone recurrent selection, was also included in the study. Glyphosate treatments were initiated in early/mid-May and applied once, twice, or three times at 4- to 5-wk intervals at rates ranging from 0.1 to 1.6 kg ae/ha. Aurora Gold was more tolerant to glyphosate than Discovery in all experiments, indicating that recurrent selection was successful in increasing glyphosate tolerance in hard fescue. Single applications of glyphosate at rates ranging from 0.6 to 0.8 kg/ha could be applied to Aurora Gold with minimal injury or stand thinning (&lt;20%), whereas multiple applications of glyphosate could be applied at rates ranging from 0.4 to 0.6 kg/ha. The use of Aurora Gold in areas planted to hard fescue, such as golf course roughs, vineyards, orchards, and landscapes, would allow the integration of direct glyphosate applications into an overall weed management program providing potential economic and environmental benefits.

Five cycles of recurrent selection for increased essential oil content in East Indian lemongrass: response to selection, and effects on heritabilities of traits and intertrait correlations

AbstractFive cycles of phenotypic recurrent selection for increased essential oil content were carried out in East Indian lemongrass, Cymbopogon flexuosus. In each cycle, the top 5% of plants for essential oil content were selected and their ramets were planted in isolated polycross blocks to produce the seed of the next cycle. Response to selection for essential oil content and its effect on three unselected traits, leaf yield, dry matter content in leaves and citral content in the essential oil, were determined by evaluating C0‐C5 populations in a replicated trial. Genetic variation, heritability estimates and intertrait correlations for essential oil content, leaf yield, leaf width, tiller number and citral content in the essential oil in C4 were determined, by evaluating 40 clones and their half‐sib progenies produced from 40 randomly selected C4 plants, in a replicated experiment. These were compared with those determined in C0 earlier. The mean essential oil content increased from 0.66% in C0 to 1.67% in C5 (i.e. by about 31% per cycle over C0). Selection for essential oil content did not affect leaf yield and its effect on dry matter content in leaves was marginal. The first three cycles of selection for essential oil content did not affect citral content in the oil but two further cycles significantly decreased citral content. Heritabilities and intertrait correlations between all traits studied, except citral content and essential oil content, were similar to those found in C0.

Selection for Orchardgrass Seed Yield in Target vs. Nontarget Environments

Simultaneous improvement of forage traits and seed yield in orchardgrass (Dactylis glomerata L.) has been problematic because of geographic separation of forage and seed production locations. Previous work has shown that a complex multilocation selection program in forage production environments can increase forage yield as well as seed yield in Oregon. The objective of this experiment was to compare target-environment (TE) and nontarget-environment (NTE) selection approaches for increasing seed yield of orchardgrass in Oregon. Two cycles of recurrent phenotypic selection for panicle seed mass (PSM) and agronomic traits were conducted on four populations in four eastern USA locations (NTE) and one Oregon location (TE). Seed yield was increased in three of four orchardgrass populations by TE selection, averaging 5.1% cycle -1 , but was improved by NTE selection in only one of four populations. Conversely, TE selection for PSM and agronomic traits resulted in no changes to forage yield in the eastern USA and Canada, while NTE selection for PSM and agronomic traits increased forage yield in two of four populations, confirming results of a previous study. It appears that the most efficient system for simultaneously improving forage and seed traits of orchardgrass would be to practice selection for forage traits in forage production environments and seed traits in seed production environments, with sufficiently large populations to allow multitrait selection.

Selection for Orchardgrass Seed Yield in Target vs. Nontarget Environments

Simultaneous improvement of forage traits and seed yield in orchardgrass (Dactylis glomerata L.) has been problematic because of geographic separation of forage and seed production locations. Previous work has shown that a complex multilocation selection program in forage production environments can increase forage yield as well as seed yield in Oregon. The objective of this experiment was to compare target-environment (TE) and nontarget–environment (NTE) selection approaches for increasing seed yield of orchardgrass in Oregon. Two cycles of recurrent phenotypic selection for panicle seed mass (PSM) and agronomic traits were conducted on four populationsin four eastern USA locations (NTE) and one Oregon location (TE). Seed yield was increased in three of four orchardgrass populations by TE selection, averaging 5.1% cycle−1, but was improved by NTE selection in only one of four populations. Conversely, TE selection for PSM and agronomic traits resulted in no changes to forage yield in the eastern USA and Canada, while NTE selection for PSM and agronomic traits increased forage yield in two of four populations, confirming results of a previous study. It appears that the most efficient system for simultaneously improving forage and seed traits of orchardgrass would be to practice selection for forage traits in forage production environments and seed traits in seed production environments, with sufficiently large populations to allow multitrait selection.

Breeding of Italian Ryegrass (Lolium multiflorum Lam.) for a low nitrate concentration by seedling test

In Japan, nitrate poisoning in ruminantscaused by the accumulation of nitrate inforage crops is a serious concern. In thisstudy, 3 cycles of phenotypic recurrentselection for nitrate concentration on adry matter basis were conducted for Italianryegrass (Lolium multiflorum Lam. cv.Nioudachi) to develop a breeding methodusing a seedling test. The seedling testinvolved the nitrate analysis of a shootfrom a plant grown for 6 or 8 weeks in thepresence of 50 mM KNO3. The selectionintensity was approximately 0.07 for eachcycle. The realized heritability of thethird generation was calculated to be 0.21for seedlings and 0.57 for adult plants. Ina pot experiment, the nitrate concentrationof the adult plants of the third generationwas found to be 60% of the value for theoriginal population at an early headingstage. The reduction is related to theincrease in dry matter (DM) content as wellas the decrease in nitrate concentration ona fresh matter basis. The original andselected populations did not differ in theheading date. The concentrations of K, Nand P in the third generation decreasedwith the increase of DM content, whereas Caand Mg concentrations remained constant. Variation in the nitrate concentration wasfound among varieties on the market. Inconclusion, the ability to accumulatenitrate is a quantitative genetic trait ofItalian ryegrass and large-scale selectionfor the breeding of low nitrate populationsis possible using a seedling test.

Selection of white clover ( Trifolium repens L.) using root traits related to dinitrogen fixation

A synthetic population of white clover was developed during three cycles of phenotypic recurrent selection in plants of two varieties, which were in second and third cycles crossed and in all cycles inoculated by Rhizobium. The plants were grown in sand hydroponics with and without mineral nitrogen. The selection criteria were aerial matter, root system size and volume of the pink (active) root nodules. The content of nitrogen in aerial matter of 21 developed and randomly chosen clones was higher by 5.5% than in the four varieties compared, due to higher concentration of nitrogen and due to higher yield. The developed synthetic population 1 The synthetic population was registered in the Czech Republic and OECD as Nivel. 1 consisting of 51 clones proved similar yield of dry matter as two standard varieties in 33 environments for 5 years on eight locations. However, it was adapted to more fertile environments as proved by regression analysis, since the regression coefficient of the yield in the environments amounted 1.121 and 1.144, when the basis of comparison of the new synthetic was average yield of two standard varieties, or yield of one of the parental varieties, respectively. It means that increased yield due to environmental influence by 1 t ha −1 proved increasing of yield in the new synthetic by 1.121 and 1.144 t ha −1, respectively. The overall averaged yield of the standard varieties from the 33 environments amounted 9.47 t ha −1, but in one-third of the most fertile environments 12.50 t ha −1 and of the new synthetic 12.97 t ha −1 (i.e. more by 3.8%).

Selecting Resistance to Bipolaris sorokiniana and Fusarium graminearum in Intermediate Wheatgrass.

Forage yield and persistence of intermediate wheatgrass and pubescent intermediate wheatgrass can be adversely affected by foot rot caused by Fusarium graminearum, Bipolaris sorokiniana, or both. Putative B. sorokiniana- and F. graminearum-resistant plants were selected from both Reliant and Manska cultivars of intermediate wheatgrass to produce four populations. When plants from half-sib families that were selected for resistance were intercrossed and progeny subjected to subsequent selection cycles for B. sorokiniana and F. graminearum resistance, progressively higher percentages of putative resistant seedlings were found for three of the four selected populations compared to the original base populations. In cycle 3 of three populations, 7 to 91% of half-sib families with statistically higher seedling survival rates than the base populations were considered more resistant than the base populations. Thus, progressive improvement in seedling survival was realized for three populations selected for resistance using three cycles of recurrent phenotypic selection among and within half-sib families.