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a Dep. of Soil and Crop Sciences, Colorado State Univ., Ft. Collins, CO 80523
b Univ. of Idaho, 3793 N 3600 E, Kimberly, ID 83341-5076
c Dep. of Bioagricultural Sciences and Pest Management, Colorado State Univ., Ft. Collins, CO 80523
d USDA-ARS, Soybean Genomics and Improvement Lab., Building 006, Plant Sciences Institute, Beltsville Agricultural Research Center, Beltsville, MD 20705-2350
* Corresponding author (Mark.Brick{at}colostate.edu).
ABSTRACT
Drought stress reduces dry bean (Phaseolus vulgaris L.) yield in more than 60% of the production regions worldwide. Pinto bean germplasm line CO46348 (Reg. No. GP-275, PI 651500) was developed by the Colorado Agricultural Experiment Station in cooperation with the University of Idaho and USDA-ARS and released 1 Apr. 2007. CO46348 is a drought-tolerant pinto bean germplasm with a 95 to 98 d growing season, high yield potential, excellent pinto seed quality, and resistance to rust caused by Uromyces appendiculatus. The complete pedigree of CO46348 is unknown; however, it was derived from a single cross made in 1989 with the pinto cultivar Othello as the female parent. Othello is a short-season pinto cultivar released in 1987 that combines excellent pinto seed color and resistance to some strains of bean common mosaic caused by Bean common mosaic virus (a potyvirus).
Abbreviations: BCMV, Bean common mosaic potyvirus • DS, drought-stress environment • HR, hypersensitive reaction • NS, nonstress environment
Drought stress reduces dry bean seed yield in most production regions worldwide (White and Singh, 1991). The release of pinto bean (Phaseolus vulgaris L.) germplasm CO46348 (Reg. No. GP-275, PI 651500) will provide plant breeders with drought-tolerant, pinto bean germplasm that takes advantage of a full growing season (95–98 d) and has high yield potential, excellent pinto seed quality, and resistance to rust caused by Uromyces appendiculatus. CO46348 was developed by the Colorado Agricultural Experiment Station in cooperation with the University of Idaho and USDA-ARS and released 1 Apr. 2007. CO46348's female parent is the pinto cultivar Othello, a short-season pinto cultivar that combines excellent pinto seed color and resistance to some strains of bean common mosaic caused by Bean common mosaic virus (a potyvirus).
In the western United States, drought occurs in both arid and semiarid regions due to inadequate summer precipitation and inadequate supplies of irrigation water, sometimes causing severe crop loss (Cook et al., 2004). Most crop production areas in the western United States use supplemental irrigation. In recent years, however, irrigation water supplies have been limited because of reduced winter precipitation needed to refill storage reservoirs and declining groundwater supplies. Perhaps the greatest threat to the availability of irrigation water in the western United States is the increasing demand and consumption of water for domestic and industrial purposes. Surface water rights are routinely purchased and transferred away from agriculture, thereby reducing the amount of water available for growing crops including dry bean. These events have created a need to identify and develop crop cultivars that use less water and can withstand drought stress. Furthermore, environmental concerns demand that improved cultivars withstand nutrient stress that results from lower amounts of applied fertilizer as a result of inadequate soil moisture. Bean cultivars with resistance to these abiotic stresses will allow western dry bean producers to reduce input costs, stabilize yields, and remain economically competitive with other bean production regions.
Drought stress has been shown to reduce dry bean biomass and seed yield. Yield loss varies depending on the severity and duration of the drought. Water stress during the vegetative stage reduces growth by reducing plant height and leaf area (Nielsen and Nelson, 1998). Stress during reproductive stages reduces seed yield by reducing biomass, pod number, and number of seeds per pod (Dubetz and Mahalle, 1969; Miller and Burke, 1983; Nielsen and Nelson, 1998; Ramírez-Vallejo and Kelly, 1998.). Drought resistance has been shown to differ among germplasm from different geographic races of common bean. Terán and Singh (2002) reported that the highest level of drought resistance in common bean occurs in race Durango germplasm that originated in the semiarid central and northern highlands of Mexico (Singh et al., 1991). In this region, the bean growing season is relatively short (
100 d) and the soils typically have limited moisture. Bean rust caused by the basidiomycete fungus Uromyces appendiculatus Pers.:Pers. Unger, is an economically important disease of common bean (Stavely and Pastor-Corrales, 1989). This disease is a threat in humid to moderately humid bean production areas worldwide and east of the Rocky Mountains in the United States. At least 80% of bean production occurs east of the continental divide from Colorado and Wyoming to Nebraska, North, Dakota, Minnesota, and Michigan, the leading dry bean–producing states in the United States. The bean rust disease tends to be recurrent in Tennessee, Florida, and eastern Colorado. The objective for the release of CO46348 was to provide plant breeders with pinto bean germplasm with tolerance to drought, full-season maturity (95–98 d), high yield potential, excellent pinto seed quality, resistance to rust, and adaptation to northern latitudes in the United States.
Methods
The complete pedigree of CO46348 is unknown. It was derived from a single cross made in 1989 with the pinto cultivar Othello as the female parent. A short-season pinto cultivar, Othello was released in 1987 and combines excellent pinto seed color and resistance to some strains of bean common mosaic caused by the Bean common mosaic potyvirus (BCMV) (Burke et al., 1995a). The pedigree for Othello is ‘NW 410’//‘Victor’/‘Aurora’. The cultivars NW 410 (Burke, 1982), Victor (Burke et al., 1995b), and Aurora are pinto, pink, and small white market classes, respectively. Seed for testing CO46348 was derived from a single F5 plant selection made in Fort Collins, CO, in 1994. From this plant, 20 seeds were planted in the greenhouse at Fort Collins to produce seed for single plant rows in 1995. Seed from 12 single plant rows was bulked to form the initial seed stocks. Subsequent increases were made in Fruita, CO, from this seed.
CO46348 was tested in 1998 by the Colorado State University Crops Testing Program and in drought-stress (DS) and nonstress (NS) environments at the University of Idaho-Kimberly Research and Extension Center, Kimberly in 2003 and 2004. The Colorado Crops Testing Program conducted yield tests on commercial crop farms in Colorado (Johnson et al., 1998). The Colorado tests used a completely randomized block design with four replicates. All planting and harvest machinery are modified commercial grain equipment. Each plot consisted of four rows of 7.62 m length and 0.76 m between rows. Approximately 16 seeds m–1 of row were planted at each site. All plots were harvested at crop maturity and seed weight adjusted to 13% moisture content.
In Idaho, Muñoz-Perea et al. (2006) evaluated dry bean landraces and cultivars released from 1932 to 1998 in DS and NS environments. Their research was conducted using furrow irrigation at University of Idaho-Kimberly Research and Extension Center in 2003 and 2004. Kimberly has average precipitation of 47 mm and an average temperature of 27°C during the growing season (June–September). The soil is a Portneuf silt loam (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid), pH 7.6, and moderate permeability in the A-horizon and slow in the B-horizon. The six pinto cultivars and one landrace were arranged in a randomized complete block design with four replicates, each in NS and DS environments. Each plot consisted of eight rows 7.62 m in length and 0.56 m between rows. An average of 23 seeds m–1 of row were planted. The NS and DS trials were planted adjacent to each other in the same field separated by a band of eight rows of dry bean in DS to reduce lateral infiltration of water from NS to DS plots. The NS trial received seven irrigations (661 mm) in 2003 and five irrigations (571 mm) in 2004 (Table 1 ). The DS trial received four irrigations (378 mm) in 2003 and two irrigations (201 mm) in 2004. The amount of irrigation water was monitored using three pairs of small trapezoidal flumes according to the procedures described by the Water Resources Research Laboratory (2001). Mean daily precipitation; minimum, maximum, and mean temperature; solar radiation; evapotranspiration; mean humidity; and average wind speed were recorded from the Twin Falls Agrimet Station (<1000 m away from the plots) at the USDA-ARS Northwest Irrigation and Soils Research Laboratory at Kimberly, ID (http://www.usbr.gov/gp/agrimet/index.cfm). Growth habit was recorded during flowering and verified at maturity. Days to maturity was recorded when 90% of the pods changed color from green to yellow. Biomass yield (kg ha–1) was determined for each genotype by cutting 10 plants at ground level at maturity and drying at 60°C for 3 d. The six central rows (25.60 m2) were cut at 108 d after planting in 2003 and 100 d in 2004, threshed 8 d later, cleaned, dried, and seed yield recorded (kg ha–1) at 12% moisture by weight. Harvest index was determined as the ratio between seed and biomass yield. Weight of 100 seeds was taken from each experimental unit and recorded.
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Characteristics
Colorado
In 1998 CO46348 was tested in Eaton, Rocky Ford, and Wiggins, CO. CO46348 had higher yield (P < 0.05) that the local check cultivar Bill Z (Wood et al., 1989) in two of the three locations (Johnson et al., 1998). In 1998 mean seed yield across the three locations for CO46348 and Bill Z were 2491 and 1923 kg ha–1, respectively (a combined statistical analysis was not conducted), and mean seed weights were 36 g 100 seed–1 for both lines when averaged over three locations in Colorado.
Idaho Stress and Nonstress Trials
Biomass Yield
The year, test environment, replication, genotype, and interaction between year and genotype were highly significant (P < 0.01) for biomass yield. No significant (P > 0.05) interaction occurred between year and test environment (DS vs. NS) and between test environment and genotype. Large differences between NS and DS occurred in overall mean for biomass yield among genotypes in 2003 and 2004 (Table 3
). CO46348 had higher biomass yield among all entries except Othello in the severe DS environment of 2003 (Table 3). When averaged over 2 yr, Buster and CO46348 had high biomass yield in both NS and DS.
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Harvest Index
Mean squares for year, test environment, genotype, and the year x test environment interaction were highly significant. The lowest average harvest index was observed in DS in 2003 (Table 3). Othello and CO46348 had the lowest reduction in harvest index due to severe drought stress in 2003. The largest harvest index reduction was observed in Topaz, Buster, and landrace Common Pinto under DS in 2003.
Seed Weight
Mean squares for year, test environment, genotype, and interaction of genotype with year and test-environment were highly significant for seed weight. Common Pinto had the smallest and Buster, CO46348, and UI 320 had the largest seed weight (Table 3). In NS seed weights for CO46348 were 37 and 39 g 100 seed–1 in 2003 and 2004, respectively, and in DS trials seed weights were 34 and 38 g 100 seed–1 in 2003 and 2004, respectively. CO46348 had higher (P < 0.05) seed weight than Bill Z in all four environments. Reduction in seed weight due to drought stress ranged from 3 to 24% in 2003 and from 0 to 10% in 2004 (Table 3). Drought-susceptible Bill Z, Common Pinto, and Topaz had higher reduction in seed weight due to drought stress. In contrast, CO46348 and Othello had the lowest reduction in seed weight over the 2 yr.
Days to Maturity
Mean squares for the number of days to maturity were significant for year, test environment, and genotype. Moreover, significant interactions occurred between year and genotype, and both interacted with the test environment. In 2003 all genotypes took longer to mature in the DS than in the NS environment (Table 3). The differences among genotypes ranged from 1 d for CO46348 to 14 d for Bill Z, Common Pinto, and Topaz. In contrast to 2003, in 2004 all genotypes except Topaz either matured the same day under DS and NS or took longer in NS than in DS.
Growth Habit
The growth habit of CO46348 was classified as indeterminate, prostrate, semivine (Type III) in both Idaho and Colorado.
Rust Reactions
CO46348 revealed a resistant reaction to all races used in this study, whereas Pinto 114 was susceptible to all (Table 2). Aurora (Ur-3) revealed a hypersensitive reaction (HR = a necrotic spot) to races 41, 53, and 108 and a susceptible reaction (large pustules) to the other races. Similarly, Early Gallatin (Ur-4) had an HR type of reaction to races 44, 49, 73, and 108 and Golden Gate Wax (Ur-6) was resistant to races 41, 44, 47, and 73. The reaction of Early Gallatin and Aurora to the other races was susceptible. PI 181996 was resistant to all but race 108, whereas PI 260418 was resistant to all eight races. The resistant reaction of these PIs was manifested as faint chlorotic spots and tiny pustules in PI 181996 and mostly as tiny pustules in PI 260418 (Table 2). The reaction of CO46348 to the eight races of the bean rust pathogen used in this study resembled that of bean germplasm lines carrying the combination of Ur-4 and Ur-11 rust-resistance genes (Pastor-Corrales and Stavely, 2002).
Germplasm such as CO46348 should be important for the future development of highly drought and rust resistant cultivars in the western United States, particularly those with pinto seed characteristics. Identifying and combining complementary drought resistant alleles from other common bean germplasm and gene pools and related Phaseolus species should allow progress for development of drought resistance.
Availability
Limited quantities of seed of CO46348 will be available for 5 yr from the corresponding author.
Acknowledgments
The development of this germplasm was financially supported by the Colorado Agricultural Experiment Station, the Colorado Dry Bean Administrative Committee, and the Colorado Seed Growers Association.
Footnotes
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.
Received for publication June 25, 2007.
References
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