| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
a Univ. of Arkansas Division of Agriculture Northeast Research and Extension Center, P.O. Box 48, Keiser, AR 72351
b Cotton Inc., 6399 Weston Pkwy., Cary, NC 27513
* Corresponding author (bourland{at}uark.edu).
ABSTRACT
Arkot 9608ne (Reg. No. GP-888, PI 651854) is a noncommercial breeding line of cotton (Gossypium hirsutum L.) that was released by the Arkansas Agricultural Experiment Station in August 2007. The line was selected from a 1996 cross of ‘MD51ne’ and Arkot 8712, and possesses the nectariless and smooth-leaf morphological traits. Lint yields of Arkot 9608ne have approximated commercial check cultivars with highest relative yields achieved in north Mississippi River Delta locations. Arkot 9608ne is early maturing and possesses improved fiber length and strength. The combinations of nectariless, smooth leaf, longer fiber length, stronger fiber strength, and specific yield adaptation and host plant resistance traits make this line valuable to cotton breeding programs.
Arkot 9608ne (Reg. No. GP-888, PI 651854) is a noncommercial breeding line of cotton, Gossypium hirsutum L. that was released by the Arkansas Agricultural Experiment Station in August 2007. Arkot 9608ne was derived from a 1996 cross of ‘MD51ne’ (Meredith, 1993) and Arkot 8712 (Bourland et al., 2005). The line was released because it possesses the nectariless and smooth-leaf morphological traits along with improved fiber quality and host plant resistance. Jenkins and Wilson (1996) reviewed articles indicating that the absence of nectaries on leaves and flowers confers resistance to tarnished plant bug [Lygus lineolaris (Palisot de Beauvois)].
Methods
Early Generation Population and Line Development
Arkot 9608ne was developed using the generalized procedures outlined by Bourland (2004). Within F1 populations grown at the Southeast Branch Station (Rohwer, AR) in 1997, bolls from visually superior individual plants were harvested and bulked. The F2 bulk populations were grown at the Northeast Research and Extension Center (Keiser, AR) in 1998, and superior individual plants were selected and harvested separately. One of the individual plants was designated as 9608-08 and was evaluated with other progenies at Keiser and Rohwer in 1999, 2000, and 2001. The progeny designated as 9608-08 was among the progenies that were selected and advanced as progeny bulks in both 1999 and 2000. Individual plant selections from 9608-08 in 2001 (F5 generation) were evaluated as progenies in 2002. One of these selections produced Arkot 9608ne (tested as 9608-08-03).
Field Test Evaluations
From 2003 through 2006, Arkot 9608ne was compared to ‘PSC 355’ and ‘SG 105’ in 14 replicated field tests at five Arkansas Agricultural Research Station sites in eastern Arkansas. Test sites included the Northeast Research and Extension Center at Keiser in 2003 to 2006; the Delta Branch Experiment Station at Clarkedale in 2003; the Judd Hill Cooperative Research Site at Judd Hill (near Trumann) in 2005 and 2006; the Lon Mann Cotton Research Station at Marianna in 2004 to 2006; and the Southeast Branch Experiment Station at Rohwer in 2003 to 2006.
Each field test was arranged in a randomized complete block design with four replications. Standard production practices, including furrow irrigation, were followed in each test. Leaf pubescence was rated each year using the rating system established by Bourland et al. (2003). Bracts were sampled and marginal trichome density was determined using methods established by Bourland and Hornbeck (2007). Percentage of open bolls was visually rated just before defoliation of the plots. Seed-cotton yields were determined by spindle machine picking the plots. Boll samples, taken from two of the four replications, were ginned on a laboratory gin. Variables determined using the gin data and samples included lint fraction, seed index, lint index, fibers per seed, seed per area, and High Volume Instrument (HVI) fiber parameters. All data were analyzed across and within locations using PROC GLM (SAS Institute, 2002).
Pest Resistance Evaluations
Response to tarnished plant bug was determined in small plot tests conducted at Keiser in 2004 through 2006. Plots (single rows, 6 m long) were replicated 12 times and were managed to encourage tarnished plant bug populations. White flowers having any discolored anthers (damaged flowers) were sequentially examined five to eight times over a 2-wk period in August of each year. A collective measure of percentage of damaged flowers over the sequential samples was determined for each plot.
During selection, Arkot 9608ne was screened for resistance to multiple races of Xanthomonas campestris pv. malvacearum (Smith) Dye, the causal agent of bacterial blight. Resistance to the multiple races conveys resistance to all known U.S. races of this pathogen.
Percentages of wilted plants associated with Verticillium wilt (caused by Verticillium dahliae Kleb) were visually estimated in field tests at Clarkedale in 2004 and at Judd Hill in 2005 and 2006. Both of these sites have naturally occurring infestations of this pathogen. Expression of the disease is dependent on environmental conditions. Response of Arkot 9608ne to Fusarium wilt [caused by Fusarium oxysporum Schlectend.:Fr. f. sp. vasinfectum (Atk.) W.C. Snyder & H.N. Hans.] was determined in the 2005 and 2006 National Cotton Fusarium Wilt Test at Tallassee, AL.
Characteristics
Field Performance
When compared over all tests, lint yields of Arkot 9608ne were equal to or greater than one of the two check cultivars each year except 2006 (Table 1
). Over all years, Arkot 9608ne yielded 4.8% less than the average of the two check cultivars. Highest relative yields of Arkot 9608ne were found at the Delta Branch Station (Clarkedale) and the Judd Hill/UA/ASU Cooperative Research Station near Trumann, AR (data not shown). Tests were conducted on a Dundee silt loam (fine-silty, mixed, active, thermic Typic Endoaqualf) at both of these northeast Arkansas locations. Lowest relative yields of Arkot 9608ne were obtained at the Lon Mann Cotton Research Station at Marianna (central Arkansas) and the Southeast Research Station at Rohwer (southeast Arkansas).
|
Compared with the check cultivars, lint yields of Arkot 9608ne were achieved with 5% more seed per area (Table 1) and 10% lower lint index (i.e., weight of lint per seed) (Table 2 ). Lewis et al. (2000) suggested that achieving lint yields on the basis of increased seed per area rather than improved lint index may contribute to less stable yield production. However, the lower lint index and 10% fewer fibers per seed associated with Arkot 9608ne were likely related to its smaller seed size (12% lower seed index than check cultivars). Consequently, Arkot 9608ne had higher lint fraction (0.8% points greater) than the check cultivars.
|
Insect and Disease Resistance
As indicated by significantly fewer damaged flowers in 2004 and 2006, Arkot 9608ne was significantly more resistant to tarnished plant bug than SG 105 and a highly susceptible Frego-bract line but equal to PSC 355 (Table 3
). The nectariless trait may provide additional resistance that was not readily measured in these tests.
|
Morphological Traits
Nectaries do not occur on leaves or flowers of Arkot 9608ne. Otherwise, morphological traits of Arkot 9608ne are similar to SG 105. Leaf pubescence and marginal bract trichome density of Arkot 9608ne were also similar to SG 105 (Table 3).
Availability
Small quantities of Arkot 9608ne seed may be obtained for breeding purposes from the corresponding author. Unless specifically approved by the Arkansas Agricultural Experiment Station, the line may not be used as recurrent parents in a breeding program.
Acknowledgments
Arkot 9608ne was developed with financial support from Arkansas Agricultural Experiment Station and Cotton Incorporated.
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 October 29, 2007.
References
| ||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| The SCI Journals | Agronomy Journal | Crop Science | |||
| Vadose Zone Journal | Soil Science Society of America Journal | ||||
| Journal of Natural Resources and Life Sciences Education |
Journal of Environmental Quality |
||||
