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Seed quality evaluation of eight kenaf cultivars
INDUSTRIALCROPS ANDPRODUCTS AN INTERNATIONAL
ELSEVIER
JOURNAL
Industrial Crops and Products 3 (1994) 213-216
Seed quality evaluation of eight kenaf cultivars C.G. Cook*, J.R. Smart USDA, AgriculturalResearch Service, SubtropicalAgticulturalResearch Laboratory,Weslaco,‘IX 78596, USA
Received 9 May, 1994; accepted 12 Augustus, 1994
Abstract Kenaf (Hibiscus cannabinus L.), a promising nonwood fiber crop, produces a high oil content seed that loses viability as exposure to high temperature and humidity increases. Because a large proportion of kenaf seed production in the United States is located in areas with high temperature and humidity, identifying kenaf germplasm with superior seed quality and resistance to weathering and seed coat pathogens should provide beneficial information to both growers and genetic improvement programs. Eight cultivars were evaluated in a darkened seed germinator in the laboratory at 18.5”C for differences in germination, susceptibility to seed coat mold growth, and coefficient of velocity of germination. Laboratory results indicated that percent germination was generally greatest for cultivars Tainung 2, Cubano, Tainung 1, Cuba 108, and Everglades 71 and lowest for 19-117-2. Susceptibility to seed coat mold growth of Cuba 108, Cubano, Tainung 2, and Everglades 71 was consistently less than 19-117-2. Coefficient of velocity of germination or rate of germination was greatest for Tainung 2 and lowest for Everglades 71. In 1991, stand establishment of Everglades 71 and Tainung 2 was greater than 19-117-2. Stand establishment and postemergence damping-off were determined at 42 days after planting. Stands of Everglades 71, Tainung 2, Cuba 108, and Tainung 1 were significantly greater than 19-117-2, 45-9, Cubano, and 78-18RSlO in the 1992 study. Cultivars differed for postemergence damping-off, with Tainung 2, Cuba 108, Tainung 1, and Cubano having less incidence than 78-18RSlO. Laboratory and field studies indicated that kenaf cultivars differed in seed quality, stand establishment, and seedling disease susceptibility. Identification and improvement of favorable seed quality traits should result in more uniform stand establishment, seedling vigor, and resistance to the seed-seedling pathogen complex. Keywords: Hibiscus cannabinus L.; Kenaf seed; Seedling disease; Germination;
1. Introduction
Kenaf (Hibiscus cannabinus L.), an annual plant of the Malvaceae family, has potential use as an alternative nonwood fiber source. Kenaf fiber can be used in the manufacture of paper and pulp products, poultry litter, animal bedding, oil absorbency pads, and carpet backing (USDA, 1993). The majority of kenaf seed production in * Corresponding author. 0926-6690/94/$07.00 0 1994 Elsevier SSDI 0926-6690(94)00038-7
Science
B.V. All rights reserved.
Stand establishment
the United States is presently located in the Lower Rio Grande Valley (LRGV) of Texas, where temperature and humidity are relatively high. Kenaf seeds, which are high in oil content, lose viability as exposure to high humidity increases (Dempsey, 1975). Planting poor-quality seed can result in reduced germination, loss of seedling vigor, susceptibility to seedling disease, and inadequate stands (personal observation). Any or all of these factors have the potential to reduce yield, fiber quality, and harvest efficiency while increasing weed
214
C.G. Cook, J.R. Smart/Industrial Crops and Products 3 (1994) 213-216
competition. Although chemical seed treatments have been reported to reduce the effects of seedseedling pathogens (White et al., 1971; Cook et al., 1992), identifying kenaf germplasm with superior genetic seed quality and increased resistance to seed-seedling pathogens could reduce the need for chemical seed protectants. The objective of this study was to determine laboratory seed germination, seed coat resistance to mold growth, coefficient of velocity of germination (CVG), field stand establishment, and postemergence dampingoff for eight kenaf cultivars. 2. Materials and methods Cultivars evaluated in this study were Everglades 71 (E71), Tainung 1 (TAl), Tainung 2 (TX!), Cubano (CUB), Cuba 108 (Clog), 19117-2 (117), 7818-RSlO (RSlO), and 45-9 (459). Cultivars used in this study were selected because of their seed availability to growers and adaptability to growing conditions in the United States. Seeds used in the experiments were produced in 1990 at Rio Farms, Inc., Monte Alto, TX. Seeds of each cultivar were exposed to similar weather and storage (lO”C, 50% relative humidity) conditions. 2.1. Laboratory studies Three laboratory tests were conducted in a darkened seed germinator at 18.5”C and 90% relative humidity. The first two tests were conducted in April and June 1991, respectively. The third test was conducted in April 1992. Seeds of each cultivar were surface sterilized for 5 min in a 1% sodium hypochlorite solution. Methodology used for the laboratory evaluations previously was reported by Cook et al. (1992) and is a modification of those procedures developed by Bird (1982) for the selection for and improvement of cotton seed quality. Twenty randomly selected seeds of each cultivar were placed on 1.5% water agar in 100 x 20 mm petri dishes. The lids of the petri dishes were removed for approximately 5 min at the time of seed placement to allow both the seeds and agar to become infested with naturally occurring fungal spores, which were primarily those of
Alternaria spp., Fusarium spp, Rhizopus spp., and Aspergillus spp. These fungi also were identified
in empty petri dishes containing potato dextrose agar. Because these fungi also are naturally occurring in the LRGV, seed were probably exposed to them prior to harvest. The dishes were arranged in a randomized complete block design, with six replications. Daily germination counts were made for seven days in the first two tests. In the third test set germination was recorded only at the termination of the study. Percentages of seed germination and seed coats supporting visible mold growth were also determined at termination of the studies. In the first two tests, CVG was calculated from daily germination counts based on the formula of Kotowski (1927). 2.2. Field studies Cultivars were also evaluated for seed quality under field conditions at Weslaco, TX on a Hidalgo sandy clay loam (fine-loamy, mixed, hyperthermic Typic Calciustolls) in 1991 and 1992. The 1991 test was located in an area previously planted with kenaf, whereas the 1992 test followed sorghum [Sorghum bicolor (L.) Moench]. Planting dates were 1 April 1991 and 8 April 1992. The experimental design was a randomized complete block with five replications. One hundred seeds of each cultivar were planted on 6.7 m single-row plots spaced 1.0 m apart. Weekly plant counts were made through 42 days after planting (DAP). Postemergence damping-off was calculated as the percent of emerged seedlings that died. Major kenaf pathogens (Fan et al., 1989) present in the soil at the Weslaco location were Rhizoctonia solani Kuhn, Pythium spp., Fusarium spp., and Alternaria SPP. 2.3. Data analysis Data from the laboratory and field experiment were analyzed by analysis of variance (SAS, 1985). When measured traits had a significant F-value (P 5 0.05), means were separated with Duncan’s Multiple Range test. Pearson correlation coefficients (r) were calculated for the laboratory traits, and field stand and postemergence damping-off.
C.G. Cook J.R. Smartllndustrial
3. Results
Germination percentage differed among cultivars (Table 1). Cultivars TA2, C108, TAl, E71, 459, and RSlO had significantly higher percentages of germination than 117. Seed coat mold growth also differed among cultivars. Seeds of cultivars E71, C108, CUB, TA2, TAl, and RSlO supported significantly less mold growth than 459 and 117. Cultivars differed for coefficient of velocity of germination, with E71 having the lowest CVG or slowest rate of germination. Across tests, TA2 had a greater CVG or faster rate of germination than E71, CUB, and RSlO. Field stand establishment differed among cultivars (Table 2). Stands ranged from 21.6 to 50.0%, with E71, TM, C108, and TAl producing greater plant stands than 459,117, CUB, and RSlO. Postemergence damping-off ranged from 8.7 to 26.1%, with cultivars E71 and RSlO having significantly more damping-off than TA2. In addition, C108, TAl, and CUB had less postemergence dampingoff than RSlO. Incidence of damping-off was significantly higher in the 1991 test (data not shown). Some of this variability in damping-off between years may have resulted from the previous cropping history, which was kenaf following kenaf in 1991 and kenaf following sorghum in 1992. Correlation coefficients among the laboratory traits and between the laboratory traits and field Table 1 Seed germination, seed coat mold growth, and coefficient of velocity of germination of eight kenaf cultivars at 7 days at 18.5”C Cultivar
Germination (%)
Tainung 2 Cuba 108 Tainung 1 Everglades 71 Cubano 45-9 78-18RSlO 19-117-2
91.6 89.1 89.1 88.1 84.7 81.6 80.0 62.2
(a) a (a) (a) (a) (ab) (b) (b) (c)
Mold growth (%)
Coefficient of velocity of germination
20.0 (ab) 15.8 (a) 23.3 (b) 14.9 (a) 19.6 (ab) 35.4 (c) 24.3 (b) 62.6 (d)
83.8 80.7 79.4 56.7 69.0 77.3 72.8 75.1
(a) (ab) (ab) (c) (b) (ab) (b) (ab)
a Means followed by the same letter are not significantly different at the 0.05 probability level according to Duncan’s multiple range test.
21.5
Crops and Products 3 (1994) 213-216
Table 2 Field stand establishment at 42 days and postemergence damping-off of eight kenaf cultivars (values are averages of five replicates of 100 seeds) Cultivar
Final stand
Damping-off
(%) Everglades 71 Tainung 2 Cuba 108 Tainung 1 45-9 19-117-2 Cubano 78-18RSlO
50.0 44.2 42.7 36.4 25.1 23.6 24.4 21.6
(%) (a) a (ab) (ab) (b) (c) (c) (c) (c)
23.4 (bc) 8.7 (a) 13.3 (ab) 15.7 (ab) 22.5 (abc) 21.8 (abc) 10.5 (ab) 26.1 (c)
a Means followed by the same letter are not significantly different at the 0.05 probability level according to Duncan’s multiple range test.
Table 3 Correlation coefficients of laboratory and field measurements
Germination Mold growth CVG Field stand
Mold growth
CVG a
Field stand
Damping-off
-0.95** -
0.03 0.16 -
0.66* -0.57 -0.12
-0.47 0.37 -0.46 -0.32
a Coefficient of velocity of germination. *,** Significance at (P 5 0.10) and (P 5 O.Ol), respectively.
measurements showed a negative and highly significant association between germination and seed coat mold growth (r = -0.95, P I 0.01) (Table 3). The only other significant correlation was a weak association between laboratory germination and field stand establishment (I = 0.66, P 5 0.10). In a previous study where E71 and TAl were evaluated with eight different fungicide seed treatments (Cook et al., 1992), CVG showed a positive association with germination and a negative correlation with seed coat mold growth. However, in this study with eight cultivars and untreated seed, CVG or rate of germination was not significantly correlated to any of the measured traits. 4. Discussion These studies indicated that the kenaf cultivars examined differed in seed quality, field stand
216
C.G. Cook, J.R. Smart/Industrial Crops and Products3 (1994) 213-216
establishment, and seed coat mold growth. Cultivars TA2, E71, C108, and TAl generally had greater laboratory germination and field stand establishment than 459, RSlO, and 117. Seed coat susceptibility to mold growth was lowest for E71 and Cl08 and greatest for 459 and 117. The lower incidence of seed coat mold growth could indicate that cultivars differ for either seed coat resistance to infection, resistance to mold growth during germination, or a combination of the two. Additional studies should be conducted to identify the mechanisms responsible for reducing seed deterioration. Cultivars TM, CUB, C108, and TAl had the lowest incidence of postemergence damping-off and suffered significantly less stand loss than E71 and RSlO. The highly significant negative relationship between germination and seed coat mold growth and the weaker association between laboratory germination and field stand establishment indicate potential problems that could be encountered due to poor seed quality. Seeds of cultivars 117 and 459 are known to have short storage-life and difficulty in establishing dense field stands (pers. observation; C. Taylor, pers. commun., 1991). This phenomenon may occur because of less genetically desirable seed quality traits, such as more rapid seed deterioration that could result from seed coat susceptibility to fungal pathogens. Since uniform, healthy stands may be associated with increased yields and harvest efficiency, identification of cultivars with superior seed qual-
ity and higher levels of resistance to the seedseedling disease complex could result in greater fiber yields. Dense plant stands also ensure reduced costs for weed control by providing early canopy closure and increased shading of the soil surface. In addition, cultivars with better seedseedling traits are valuable genetic resources in breeding programs to develop improved kenaf cultivars. References Bird, L.S., 1982. The MAR (multi-adversity resistance) system for genetic improvement of cotton. Plant Dis., 66: 172176. Cook, C.G., Hickman, M.V., Webber, C.L., Sij, J.W. and Scott, A.W., 1992. Fungicide treatment effects on kenaf seed germination and stand establishment. Ind. Crops Products, 1: 41-45. Dempsey, J.M., 1975. Fiber Crops. The University Presses of Florida, Gainesville, Fla., 457 pp. Farr, D.F., Bills, GE, Chamuris, G.P and Rossman, A.Y., 1989. Fungi on plants and plant products in the United States. The American Phytopathological Society. St. Paul, Minn., 373 pp. Kotowski, E, 1927. Temperature relations to germination of vegetable seed. Proc. Am. Sot. Hort. Sci., 23: 176-184. SAS Institute. 1985. SAS User’s Guide: Statistics, 5th ed. SAS Institite, Cary, N.C. USDA, 1993. New industrial uses, new markets for U.S. crops: status of technology and commercial adoption. Cooperative State Research Service, Office of Agricultural Materials, Washington, DC., 79 pp. White, G.A., Adamson, W.C., Whitely, E.L. and Massey, J.H., 1971. Emergence of kenaf seedlings as affected by seed fungicides. Agron. J., 63: 484-486.
ELSEVIER
JOURNAL
Industrial Crops and Products 3 (1994) 213-216
Seed quality evaluation of eight kenaf cultivars C.G. Cook*, J.R. Smart USDA, AgriculturalResearch Service, SubtropicalAgticulturalResearch Laboratory,Weslaco,‘IX 78596, USA
Received 9 May, 1994; accepted 12 Augustus, 1994
Abstract Kenaf (Hibiscus cannabinus L.), a promising nonwood fiber crop, produces a high oil content seed that loses viability as exposure to high temperature and humidity increases. Because a large proportion of kenaf seed production in the United States is located in areas with high temperature and humidity, identifying kenaf germplasm with superior seed quality and resistance to weathering and seed coat pathogens should provide beneficial information to both growers and genetic improvement programs. Eight cultivars were evaluated in a darkened seed germinator in the laboratory at 18.5”C for differences in germination, susceptibility to seed coat mold growth, and coefficient of velocity of germination. Laboratory results indicated that percent germination was generally greatest for cultivars Tainung 2, Cubano, Tainung 1, Cuba 108, and Everglades 71 and lowest for 19-117-2. Susceptibility to seed coat mold growth of Cuba 108, Cubano, Tainung 2, and Everglades 71 was consistently less than 19-117-2. Coefficient of velocity of germination or rate of germination was greatest for Tainung 2 and lowest for Everglades 71. In 1991, stand establishment of Everglades 71 and Tainung 2 was greater than 19-117-2. Stand establishment and postemergence damping-off were determined at 42 days after planting. Stands of Everglades 71, Tainung 2, Cuba 108, and Tainung 1 were significantly greater than 19-117-2, 45-9, Cubano, and 78-18RSlO in the 1992 study. Cultivars differed for postemergence damping-off, with Tainung 2, Cuba 108, Tainung 1, and Cubano having less incidence than 78-18RSlO. Laboratory and field studies indicated that kenaf cultivars differed in seed quality, stand establishment, and seedling disease susceptibility. Identification and improvement of favorable seed quality traits should result in more uniform stand establishment, seedling vigor, and resistance to the seed-seedling pathogen complex. Keywords: Hibiscus cannabinus L.; Kenaf seed; Seedling disease; Germination;
1. Introduction
Kenaf (Hibiscus cannabinus L.), an annual plant of the Malvaceae family, has potential use as an alternative nonwood fiber source. Kenaf fiber can be used in the manufacture of paper and pulp products, poultry litter, animal bedding, oil absorbency pads, and carpet backing (USDA, 1993). The majority of kenaf seed production in * Corresponding author. 0926-6690/94/$07.00 0 1994 Elsevier SSDI 0926-6690(94)00038-7
Science
B.V. All rights reserved.
Stand establishment
the United States is presently located in the Lower Rio Grande Valley (LRGV) of Texas, where temperature and humidity are relatively high. Kenaf seeds, which are high in oil content, lose viability as exposure to high humidity increases (Dempsey, 1975). Planting poor-quality seed can result in reduced germination, loss of seedling vigor, susceptibility to seedling disease, and inadequate stands (personal observation). Any or all of these factors have the potential to reduce yield, fiber quality, and harvest efficiency while increasing weed
214
C.G. Cook, J.R. Smart/Industrial Crops and Products 3 (1994) 213-216
competition. Although chemical seed treatments have been reported to reduce the effects of seedseedling pathogens (White et al., 1971; Cook et al., 1992), identifying kenaf germplasm with superior genetic seed quality and increased resistance to seed-seedling pathogens could reduce the need for chemical seed protectants. The objective of this study was to determine laboratory seed germination, seed coat resistance to mold growth, coefficient of velocity of germination (CVG), field stand establishment, and postemergence dampingoff for eight kenaf cultivars. 2. Materials and methods Cultivars evaluated in this study were Everglades 71 (E71), Tainung 1 (TAl), Tainung 2 (TX!), Cubano (CUB), Cuba 108 (Clog), 19117-2 (117), 7818-RSlO (RSlO), and 45-9 (459). Cultivars used in this study were selected because of their seed availability to growers and adaptability to growing conditions in the United States. Seeds used in the experiments were produced in 1990 at Rio Farms, Inc., Monte Alto, TX. Seeds of each cultivar were exposed to similar weather and storage (lO”C, 50% relative humidity) conditions. 2.1. Laboratory studies Three laboratory tests were conducted in a darkened seed germinator at 18.5”C and 90% relative humidity. The first two tests were conducted in April and June 1991, respectively. The third test was conducted in April 1992. Seeds of each cultivar were surface sterilized for 5 min in a 1% sodium hypochlorite solution. Methodology used for the laboratory evaluations previously was reported by Cook et al. (1992) and is a modification of those procedures developed by Bird (1982) for the selection for and improvement of cotton seed quality. Twenty randomly selected seeds of each cultivar were placed on 1.5% water agar in 100 x 20 mm petri dishes. The lids of the petri dishes were removed for approximately 5 min at the time of seed placement to allow both the seeds and agar to become infested with naturally occurring fungal spores, which were primarily those of
Alternaria spp., Fusarium spp, Rhizopus spp., and Aspergillus spp. These fungi also were identified
in empty petri dishes containing potato dextrose agar. Because these fungi also are naturally occurring in the LRGV, seed were probably exposed to them prior to harvest. The dishes were arranged in a randomized complete block design, with six replications. Daily germination counts were made for seven days in the first two tests. In the third test set germination was recorded only at the termination of the study. Percentages of seed germination and seed coats supporting visible mold growth were also determined at termination of the studies. In the first two tests, CVG was calculated from daily germination counts based on the formula of Kotowski (1927). 2.2. Field studies Cultivars were also evaluated for seed quality under field conditions at Weslaco, TX on a Hidalgo sandy clay loam (fine-loamy, mixed, hyperthermic Typic Calciustolls) in 1991 and 1992. The 1991 test was located in an area previously planted with kenaf, whereas the 1992 test followed sorghum [Sorghum bicolor (L.) Moench]. Planting dates were 1 April 1991 and 8 April 1992. The experimental design was a randomized complete block with five replications. One hundred seeds of each cultivar were planted on 6.7 m single-row plots spaced 1.0 m apart. Weekly plant counts were made through 42 days after planting (DAP). Postemergence damping-off was calculated as the percent of emerged seedlings that died. Major kenaf pathogens (Fan et al., 1989) present in the soil at the Weslaco location were Rhizoctonia solani Kuhn, Pythium spp., Fusarium spp., and Alternaria SPP. 2.3. Data analysis Data from the laboratory and field experiment were analyzed by analysis of variance (SAS, 1985). When measured traits had a significant F-value (P 5 0.05), means were separated with Duncan’s Multiple Range test. Pearson correlation coefficients (r) were calculated for the laboratory traits, and field stand and postemergence damping-off.
C.G. Cook J.R. Smartllndustrial
3. Results
Germination percentage differed among cultivars (Table 1). Cultivars TA2, C108, TAl, E71, 459, and RSlO had significantly higher percentages of germination than 117. Seed coat mold growth also differed among cultivars. Seeds of cultivars E71, C108, CUB, TA2, TAl, and RSlO supported significantly less mold growth than 459 and 117. Cultivars differed for coefficient of velocity of germination, with E71 having the lowest CVG or slowest rate of germination. Across tests, TA2 had a greater CVG or faster rate of germination than E71, CUB, and RSlO. Field stand establishment differed among cultivars (Table 2). Stands ranged from 21.6 to 50.0%, with E71, TM, C108, and TAl producing greater plant stands than 459,117, CUB, and RSlO. Postemergence damping-off ranged from 8.7 to 26.1%, with cultivars E71 and RSlO having significantly more damping-off than TA2. In addition, C108, TAl, and CUB had less postemergence dampingoff than RSlO. Incidence of damping-off was significantly higher in the 1991 test (data not shown). Some of this variability in damping-off between years may have resulted from the previous cropping history, which was kenaf following kenaf in 1991 and kenaf following sorghum in 1992. Correlation coefficients among the laboratory traits and between the laboratory traits and field Table 1 Seed germination, seed coat mold growth, and coefficient of velocity of germination of eight kenaf cultivars at 7 days at 18.5”C Cultivar
Germination (%)
Tainung 2 Cuba 108 Tainung 1 Everglades 71 Cubano 45-9 78-18RSlO 19-117-2
91.6 89.1 89.1 88.1 84.7 81.6 80.0 62.2
(a) a (a) (a) (a) (ab) (b) (b) (c)
Mold growth (%)
Coefficient of velocity of germination
20.0 (ab) 15.8 (a) 23.3 (b) 14.9 (a) 19.6 (ab) 35.4 (c) 24.3 (b) 62.6 (d)
83.8 80.7 79.4 56.7 69.0 77.3 72.8 75.1
(a) (ab) (ab) (c) (b) (ab) (b) (ab)
a Means followed by the same letter are not significantly different at the 0.05 probability level according to Duncan’s multiple range test.
21.5
Crops and Products 3 (1994) 213-216
Table 2 Field stand establishment at 42 days and postemergence damping-off of eight kenaf cultivars (values are averages of five replicates of 100 seeds) Cultivar
Final stand
Damping-off
(%) Everglades 71 Tainung 2 Cuba 108 Tainung 1 45-9 19-117-2 Cubano 78-18RSlO
50.0 44.2 42.7 36.4 25.1 23.6 24.4 21.6
(%) (a) a (ab) (ab) (b) (c) (c) (c) (c)
23.4 (bc) 8.7 (a) 13.3 (ab) 15.7 (ab) 22.5 (abc) 21.8 (abc) 10.5 (ab) 26.1 (c)
a Means followed by the same letter are not significantly different at the 0.05 probability level according to Duncan’s multiple range test.
Table 3 Correlation coefficients of laboratory and field measurements
Germination Mold growth CVG Field stand
Mold growth
CVG a
Field stand
Damping-off
-0.95** -
0.03 0.16 -
0.66* -0.57 -0.12
-0.47 0.37 -0.46 -0.32
a Coefficient of velocity of germination. *,** Significance at (P 5 0.10) and (P 5 O.Ol), respectively.
measurements showed a negative and highly significant association between germination and seed coat mold growth (r = -0.95, P I 0.01) (Table 3). The only other significant correlation was a weak association between laboratory germination and field stand establishment (I = 0.66, P 5 0.10). In a previous study where E71 and TAl were evaluated with eight different fungicide seed treatments (Cook et al., 1992), CVG showed a positive association with germination and a negative correlation with seed coat mold growth. However, in this study with eight cultivars and untreated seed, CVG or rate of germination was not significantly correlated to any of the measured traits. 4. Discussion These studies indicated that the kenaf cultivars examined differed in seed quality, field stand
216
C.G. Cook, J.R. Smart/Industrial Crops and Products3 (1994) 213-216
establishment, and seed coat mold growth. Cultivars TA2, E71, C108, and TAl generally had greater laboratory germination and field stand establishment than 459, RSlO, and 117. Seed coat susceptibility to mold growth was lowest for E71 and Cl08 and greatest for 459 and 117. The lower incidence of seed coat mold growth could indicate that cultivars differ for either seed coat resistance to infection, resistance to mold growth during germination, or a combination of the two. Additional studies should be conducted to identify the mechanisms responsible for reducing seed deterioration. Cultivars TM, CUB, C108, and TAl had the lowest incidence of postemergence damping-off and suffered significantly less stand loss than E71 and RSlO. The highly significant negative relationship between germination and seed coat mold growth and the weaker association between laboratory germination and field stand establishment indicate potential problems that could be encountered due to poor seed quality. Seeds of cultivars 117 and 459 are known to have short storage-life and difficulty in establishing dense field stands (pers. observation; C. Taylor, pers. commun., 1991). This phenomenon may occur because of less genetically desirable seed quality traits, such as more rapid seed deterioration that could result from seed coat susceptibility to fungal pathogens. Since uniform, healthy stands may be associated with increased yields and harvest efficiency, identification of cultivars with superior seed qual-
ity and higher levels of resistance to the seedseedling disease complex could result in greater fiber yields. Dense plant stands also ensure reduced costs for weed control by providing early canopy closure and increased shading of the soil surface. In addition, cultivars with better seedseedling traits are valuable genetic resources in breeding programs to develop improved kenaf cultivars. References Bird, L.S., 1982. The MAR (multi-adversity resistance) system for genetic improvement of cotton. Plant Dis., 66: 172176. Cook, C.G., Hickman, M.V., Webber, C.L., Sij, J.W. and Scott, A.W., 1992. Fungicide treatment effects on kenaf seed germination and stand establishment. Ind. Crops Products, 1: 41-45. Dempsey, J.M., 1975. Fiber Crops. The University Presses of Florida, Gainesville, Fla., 457 pp. Farr, D.F., Bills, GE, Chamuris, G.P and Rossman, A.Y., 1989. Fungi on plants and plant products in the United States. The American Phytopathological Society. St. Paul, Minn., 373 pp. Kotowski, E, 1927. Temperature relations to germination of vegetable seed. Proc. Am. Sot. Hort. Sci., 23: 176-184. SAS Institute. 1985. SAS User’s Guide: Statistics, 5th ed. SAS Institite, Cary, N.C. USDA, 1993. New industrial uses, new markets for U.S. crops: status of technology and commercial adoption. Cooperative State Research Service, Office of Agricultural Materials, Washington, DC., 79 pp. White, G.A., Adamson, W.C., Whitely, E.L. and Massey, J.H., 1971. Emergence of kenaf seedlings as affected by seed fungicides. Agron. J., 63: 484-486.