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Ecological Effects of Flaveria Bidentis in Cotton Field and Its Chemical Control

Author: PengJun
Tutor: LiXiangJu
School: Chinese Academy of Agricultural Sciences
Course: Pesticides
Keywords: WONG bidentis , Cotton fields Competitive effect Allelopathy Biological activity Chemical Control
CLC: S451
Type: Master's thesis
Year: 2011
Downloads: 48
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Abstract

The Flaveria Ju (Flaveria bidentis (L.) Kuntz) originating in South America, is important invasive weeds in China in recent years. Are mainly semi-arid cotton-growing areas of central and southern Hebei epidemic distribution point 15 million occurrence area of ??23,000 ha ^{2 . Tianjin, Henan and Shandong have occurred. Flaveria daisy occurred during the growth environment and regional distribution agreement with cotton, is a threat to China's cotton production potential \-Competitive effects of this study from the yellow bidentis with cotton, cotton fields Allelopathy, chemical control of the four aspects of the cotton fields of biological active and cotton fields conducted research. The main results are as follows: 1. Cotton by Flaveria daisy invasion affect flower bud stage plant height increased significantly, a 5.7% increase, while the fruit branch number, bud number reduce, to F. bidentis was 4 to 8 plants / 8 meters governors to reduce the most obvious, decrease 6.25% to 36.7%; small boll of cotton boll number decrease of 62.8%, fruit branch number, boll number representing a decrease of 11.6% and 5.59%; boll opening of cotton plant stem diameter narrowing, a reduction of up to 18.8%. Only 4.4 / strains of cotton bolls per plant when the yellow the top daisy-density for the 4/8 m governors, representing a decrease of 36.6%; the Flaveria bidentis 20/8 meters governor density of cotton symbiotic period of more than four weeks, the cotton plant stem diameter reduced by 2.8% to 16.0%, a significant reduction in cotton production more than eight weeks, 10 weeks the effective number of bolls of cotton per plant decreased by 63.7%, 61.2% reduction in the number of acres boll, seed cotton and lint cut by 62.8% and 61.3%, respectively. The resulting yellow bidentis cotton has strong invasive and competitive, 4/8 meter governor should be lower than the density symbiotic period of eight weeks before controlling its economic threshold of 2/8 m controlling president. . The yellow bidentis different growth stages of extraction liquid germination of weed seeds Cotton, from May to July strongest inhibition, 8 October weakened. The low concentration of extract can promote barnyard grass seed germination, high concentrations inhibit the germination of barnyardgrass. The the Flaveria purpurea root extract can promote the growth of barnyard grass radicle and germ the flower extract performance high concentrations inhibited, stem, leaf extract of barnyard grass radicle and germ was inhibited by low concentrations promote, and with concentration inhibition increased; each organ extract velvetleaf seed germination and the inhibition performance leaves gt; spend gt; roots, stems, Abutilon radicle and germ inhibition performance with Flaveria purpurea root, stem extract concentration improve suppression enhancement flower extract showed low concentrations to promote high concentration inhibition; Huang bidentis organ extract Eclipta prostrata seed germination of the strength of the order of the leaves, stems, flowers gt; promote Eclipta prostrata radicle roots, dig up the roots to the low concentration germ growth, the rest of the organ extracts tested concentrations inhibited Eclipta prostrata radicel, germ growth, with the concentration and strengthen; Huang bidentis different organ extract inhibited germination of cotton seeds, the degree of inhibition showed leaf flower gt; stem gt; roots. Yellow bidentis different organs, different concentrations of extract have different effects on different cotton varieties the radicle, germ growth, its flower extract CCRI 36 radicle germ growth were to play a catalytic role to promote CCRI 75 radicle growth inhibited germ growth, CCRI 76 radicle, plumule disincentive. Comprehensive analysis The yellow bidentis strong allelopathic potential, this potential also indicates that in the cotton fields a strong competitive advantage and risk of invasion. Litura Huang bidentis 1g dry weight · ml ^{to -1 direct spray of water extract 72h survival rate of only 54.17%, Baptist Leaf 24h and 48h survival rates were 70.00% and 80.00 % and 62.00% to 74.00%; the yellow bidentis different organizations and the artificial diet press 1:6 Hunban, flower Hunban stomach toxicity slightly stronger, Helicoverpa armigera, Spodoptera litura mortality were 5.0% and 3.33%; leaves, flowers obvious growth inhibition of H. armigera, larvae ratio dropped to 76.67% and 56.67%, 81.67% lower than that of the control; leaves no obvious effect on the growth of Spodoptera litura affect performance, spend significantly inhibited 4 instar compared to just 13.33%; flowers, stems significantly inhibited Spodoptera litura worm weight inhibition rates were 57.26% and 10.07%, respectively, and leaves no obvious effect; flowers and stems of Spodoptera litura male, female pupal weight inhibition rate were 12.14% and 19.73% , emergence rate decreased from 64.00% to 72.00%, which spent the strongest inhibition; the Flaveria the chrysanthemum leaves Hunban feed allows the Spodoptera litura pupation postpone the peak period of about three days, the flower Hunban feed about 10 days later; stem Hunban to feed twill armyworm male, female pupal eclosion time about 5 days and 3 days later; leaves, flowers Hunban feed delayed 2 to 3 days, and the female pupae postponed more evident than male pupae. Cotton Soil treatment of herbicide inhibition rate of 97.11% to 96% fine metolachlor EC720.0 ~~ 1440.0g ai · hm ^{-2 handling of the yellow bidentis control efficiency, seed germination to 99.32%, root length inhibition rate of 73.41% to 89.40%, the bud inhibition rate of 63.09% to 93.85%; 48% trifluralin EC1081.1 ~~ 1621.6g ai · hm ^{-2 Flaveria purpurea root long inhibition rate highest, up to 78.97% to 81.87%; 90% of acetochlor EC1687.5 to 3375.0g ai · hm ^{-2 Flaveria chrysanthemum bud highest inhibition rate up to 60.84% ??to 73.41 %; 50% prometryn WP1404.5 2343.8g ai · hm ^{-2 treatment also showed a higher control efficiency. Foliar treatment herbicides ether 25% fluorine sulfonamides grass the AS control effect, 281.5 to 563.1g ai · hm ^{-2 21 days after treatment chrysanthemum strains of Flaveria control efficiency of 89.06% to 100%, fresh weight efficiency 95.90% to 100%; 20% paraquat AS375.0 1127.8g ai · hm ^{-2 75% trifluoroacetic piperidine metsulfuron sodium salt WP14.1 to 28.1 g of ai · hm ^{-2 , 75% ether pyrithiobac grass WP562.5 ~ 1125.0g ai · hm ^{-2 and 41% glyphosate AS768.8 ~ 2312.0g ai · hm ^{-2 of the yellow bidentis anti efficiency also ideal, can be used as the cotton fields Flaveria daisy stems directed spray controlling Pharmacy; the 10% Fluoroglycofen ether EC and 50% Napropamide, WP processing Flaveria daisy anti- efficiency is poor. The results of this study further to clear yellow bidentis cotton field ecology guidance cotton fields Flaveria daisy chemical control has greater practical significance.}}}}}}}}}}}

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