scholarly journals Morphological and Biochemical Bases of Resistance of Some Groundnut Germplasms against Tobacco Caterpillar, Spodoptera litura (Fabricius) and Leaf Miner, Aproaerema modicella (Deventer)

2021 ◽  
pp. 195-204
Author(s):  
Shaik Moizur Rahman ◽  
K Vijayalakshmi ◽  
Ch. V. Durga Rani ◽  
S. Ameer Basha ◽  
C. Srinivas
Keyword(s):  
Insect Pests ◽  
Block Design ◽  
Insect Pest ◽  
Leaf Damage ◽  
Leaf Miner ◽  
College Of Agriculture ◽  
Pest Damage ◽  
Randomized Block Design ◽  
Germplasm Line ◽  
Tobacco Caterpillar

A screening experiment of forty germplasm lines was conducted at College Farm, College of Agriculture, Rajendranagar, Hyderabad in rabi, 2019-20 and was laid in Randomized block design (RBD) having two replicates. Three germplasm lines viz., ICGV 16679 (13.71% leaf damage), ICGV 07222 (14.00% leaf damage) and ICGV 93468 (14.25% leaf damage) showed greater resistance than the resistant check, ICGV 86031 (15.04% leaf damage) against tobacco caterpillar and with respect to resistance against leaf miner, no germplasm line was found to be superior than the resistant check, ICGV 86031 (7.82% leaf damage). However, the germplasm line, ICGV 02266 (8.35% leaf damage) was next best to the resistant check. The various morphological and biochemical characters were recorded and correlated with insect pest damage and incidence to know their role in imparting resistance/susceptibility. Resistance to various insect pests in germplasm lines was due to significantly higher trichome density on leaf lamina, higher phenol and tannin content.

scholarly journals APLIKASI PUPUK DAN MULSA JERAMI PADA TANAMAN KEDELAI TERHADAP SERANGAN HAMA DAN PRODUKSI

EUGENIA ◽  
2015 ◽  
Vol 21 (1) ◽  
Author(s):  
J. Rimbing ◽  
J. Pelealu ◽  
D. Sualang
Keyword(s):  
Insect Pests ◽  
Block Design ◽  
Insect Pest ◽  
Inorganic Fertilizer ◽  
Flying Insects ◽  
Randomized Block Design ◽  
Soybean Pest ◽  
Crop Damages ◽  
Virus Attack ◽  
Soybean Plants

ABSTRACT   The research was arranged in a randomized block design (RBD), with 10 treatments and 3 replications. To get the active insects pests, net sweepings were done for the flying insects, while other pests were observed directly on the plants. Collecting data of plant damages were made by systematic diagonal lines, except for viruses, census was conducted on each experimental plot.  The results of this experiment documented 12 species of insect pests attacking soybean plants. Soybean pest populations were relatively low, except for Aphis glycine that was quite high. In all treatments, plant damage caused by sucking pest Piezodorus sp and Riptortus linearis were relatively low of 1.53 % to 1.94 %; it indicated an insignificant effect to decline the production. Crop damages by virus showed a significant effect. The lowest virus attacks found on compost of 5 tons per ha with 43 plants infected per treatment, the highest virus attack showed on combination of 5 tons compost per ha + inorganic fertilizer + mulch, in which there were 274 infected plants per treatment. Apparently virus attacks gave impact on soybean production. The highest production were documented on treatment of 5 tons compost per ha with production of 0.55 tons per ha, while the lowest production was found on combination of 5 tons compost per ha + inorganic fertilizer + mulch, in which the production was 0.22 tons per ha. Keywords:  fertilizer, mulch, insect pest, production

scholarly journals Screening of Genotypes against Major Sucking Insect- Pests of Mothbean [Vigna aconitifolia] in Arid Region

2021 ◽  
pp. 80-88
Author(s):  
K. L. Naga ◽  
A. R. Naqvi ◽  
B. L. Naga ◽  
H. L. Deshwal ◽  
L. Jhumar
Keyword(s):  
Integrated Pest Management ◽  
Pest Management ◽  
Arid Region ◽  
Insect Pests ◽  
Block Design ◽  
Insect Pest ◽  
Management Programme ◽  
Natural Resistance ◽  
Vigna Aconitifolia ◽  
Randomized Block Design

Aim: Some genotypes of mothbean were screened for their comparative preference against jassids, whiteflies and thrips. Materials and Methods: The experiment was laid out during Kharif season in Randomized Block Design with three Replications. Ten genotypes (viz., RMO-225, RMO-40, RMO-423, RMO-435, RMO-257, RMO-25, RMO-141, RMO-20-36, RMO-04-01-28 and RMO-28-80) were screened against major sucking insect pests which were replicated thrice. Observations: The observations were recorded after two weeks of sowing at weekly intervals after two weeks of sowing. The pest populations were recorded on five randomly selected and tagged plants per plot in early hours when insect have minimum activity. Results: The data revealed that none of the genotypes ware found free from sucking insect pest attack. On the basis of peak population, the genotypes RMO-25 and RMO-141 were categorized as least preferred to jassids, whiteflies and thrips, whereas, RMO-435, RMO-225 and RMO-04-01-28 as highly preferred to jassids and whiteflies and RMO-435, RMO-225 and RMO-257 as highly resistant to thrips. Conclusion: It is well known that certain genotypes of crops are less attacked by a specific insect-pest than others because of natural resistance. In the integrated pest management programme, growing of varieties (RMO-25 and RMO-141) with less preference to sucking insect-pests is one of the most important tools without additional cost.

scholarly journals ​Bio-efficacy of Chemical Insecticides and Biopesticides against Gram Pod Borer, Helicoverpa armigera (Hubner) and Spotted Pod Borer, Maruca testulalis (Geyer) on Greengram, [Vigna radiata (L.) Wilczek]

2021 ◽  
Author(s):  
V.P. Meena ◽  
S.K. Khinchi ◽  
D.K. Bairwa ◽  
Akhter Hussain ◽  
K.C. Kumawat ◽  
...  
Keyword(s):  
Helicoverpa Armigera ◽  
Vigna Radiata ◽  
Insect Pests ◽  
Block Design ◽  
Maruca Testulalis ◽  
College Of Agriculture ◽  
Randomized Block Design ◽  
Pod Borer ◽  
Helicoverpa Armígera ◽  
Helicoverpa Armigera Hubner

Background: Gram pod borer, Helicoverpa armigera (Hubner) and spotted pod borer, Maruca testulalis (Geyer) are important pod boring insects infesting the greengram, [Vigna radiata (L.) Wilczek] throughout the India. A number of synthetic insecticides are known to be effective against these borers but most of them have been phased out as a result of high toxicity to the pollinators and other biotic fauna, therefore, a group of new chemical insecticides with biopesticides have been tested for bioefficacy against these insect pests. Method: A field experiment was conducted at S.K.N. College of Agriculture, Jobner, Rajasthan during kharif, 2018 in randomized block design (RBD) with 9 treatments and 3 replications. The observations were recorded of Helicoverpa armigera (Hubner) and spotted pod borer, Maruca testulalis (Geyer) borers one day before and 1, 3, 7 and 15 days after application of insecticides and biopesticides in each the spray from ten randomly selected and tagged plants/ plot. From the data recorded per cent reduction in population over control was calculated. The per cent pod damage was calculated by counting damaged pods out of healthy pods of greengram. Result: The spinosad 45 SC (0.01%) proved to be most effective, indoxacarb 14.5 SC (0.01%) followed by fipronil 5 SC (0.01%), whereas, treatments of neem leaf extract (10.00%), Beauveria bassiana 1.15 WP 1X108 spore/ l proved to be least effective. The maximum seed yield of 9.13 q ha–1 was obtained in the plots treated with spinosad 45 SC (0.01%) followed by indoxacarb 14.5 SC (0.01%) (8.89 q ha-1), fipronil 5 SC (0.01%) (8.60 q ha-1).

scholarly journals Assessment of leaf miner Liriomyza spp (diptera: Agromyzidae) damage on tomato and the yield output in Ilorin, Southern Guinea Savannah, Nigeria

Agrosearch ◽  
2021 ◽  
Vol 20 (2) ◽  
pp. 1-9
Author(s):  
S. Mustapha ◽  
A.K. Musa ◽  
A.S. Aliyu
Keyword(s):  
Block Design ◽  
Insect Pest ◽  
Experimental Treatment ◽  
Control Measures ◽  
Leaf Damage ◽  
Leaf Miner ◽  
Tomato Fruits ◽  
Tomato Plants ◽  
Significant Difference ◽  
Screen House

Tomato plays an important nutritional role in human diet. Although, Nigeria is the largest producers of tomato in Africa, its production is threatened by the invasive polyphagous insect pest belonging to the genus Liriomyza. An experiment was conducted to enumerate the level of damage of the agromyzid fly Liriomyza spp on the tomato variety, UC82B. Infestations were observed on potted tomato plants and studied from December 2016 to March, 2017. The experimental treatment consisted of both screen house and field trials. The experiment was laid out in a Randomized Complete Block Design with four replicates. Data were collected on the number of tomato leaves mined by larvae of the pest every week after transplanting (WAT) and on the total weight of tomato fruits harvested. Using t-test statistical analysis, results revealed that tomato plants grown in the field were the most infested by the insect pest from 5 to 10 WAT having significantly higher (P < 0.05) mean population of the pest when compared to the screen house which had little or no infestation. However, there was no significant difference in the leaf damage by Liriomyza spp from 2 to 4 WAT. Tomato fruits harvested at the end of the experiment were weighed and observation showed that the screen house gave more fruit yield (90.80±6.10g) compared to the field experiment (24.20±2.27g) which was significantly lower due to leaf miner flies’ damage on tomato leaves. Therefore, appropriate control measures of the insect pest are recommended where screen houses may not be accessible.

​Effects of Genotypic Diversity on Insect-pests of Soybean

2021 ◽  
Author(s):  
Lokesh Kumar Meena ◽  
Vangala Rajesh ◽  
Amar Nath Sharma
Keyword(s):  
Effective Treatment ◽  
Natural Enemy ◽  
Agronomic Traits ◽  
Insect Pests ◽  
Block Design ◽  
Insect Pest ◽  
Genotypic Diversity ◽  
Intraspecific Diversity ◽  
Small Scale ◽  
Randomized Block Design

Background: Intercropping and mixed cropping based on two or more different crops have been widely used in Insect Pest Management to manage the population density of insect pests in various crops like maize with soybean, sorghum with soybean and sunflower with soybean. Genotypic diversity is the mixture or combination of various varieties/lines/genotypes of a crop. It decreases the insect-pests population by unfitness of crop to them due to intraspecific diversity such as mixture of susceptible and resistant varieties. Also, it increases the natural enemy population more due to longer period of flowering, availability of wide diverse food, more movement of herbivores etc. This concept has also been used successfully to manage insect-pests in maize, wheat and potato. In India, this connect is used in very small scale in crop. The objective of this study was to determine effects of genotypic diversity by comparing the population densities of major insect pests between monoculture of single variety and mixture of varieties. Methods: To test the effects of genotypic diversity on soybean insect-pest and their natural enemy population an experiment was laid in kharif 2018 and 2019 at the ICAR-Indian Institute of Soybean Research, Indore. All recommended agronomic package of practices were followed for raising of crop. Randomized block design with three replication having plot size of 9 rows of 5 meter row length was used. Totally 20 treatments were chosen for this experiment and out of 20 four treatments namely, T1, T6, T11 and T16 were the treatments of four varietal mixture treatments of almost similar maturity duration and agronomic traits and rest of treatments were of sole varietal treatments. Observations were made on insect-pests from 10 selected plants in each plot on three leaves selected at top, middle and lower portion of plant. Result: Effects of genotypic diversity in soybean revealed that for whitefly management T11 (NRC-86, JS-335, JS-2098 and RKS-45) was found most effective treatment. In case of mite, thrips and treehoppers management T1 (JS-9560, JS-20-34, MAUS-47 and MAUS-1460) was found most effective treatment. For leafhopper and mealy bug T6 (JS-9305, JS-2029, RVS-2001-4 and Dsb-28-3) was found most effective treatment. While for spittlebug T16 (NRC-37, JS-9752, RSC-1046 and RKS-113) was found most effective treatment. So, genotypic diverse treatments were found more effective than their respective sole varietal treatments.

scholarly journals Respons Lima Varietas Kubis (Brassica oleracea L.) Terhadap Serangan Hama Pemakan Daun Plutella Xylostella ( Lepidoptera ; Plutellidae)

Agrologia ◽  
2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Jerry. N Luhukay ◽  
Muhammad Riadh Uluputty ◽  
Ria Y Rumthe
Keyword(s):  
Plutella Xylostella ◽  
Crop Production ◽  
Block Design ◽  
Leaf Damage ◽  
Pests And Diseases ◽  
Pest Damage ◽  
Randomized Block Design ◽  
Brassica Oleraceae ◽  
High Yielding Varieties ◽  
The Village

Efforts to increase crop production often faced difficulty with pests and diseases. The use of high yielding varieties can be an alternative control. This study aimed to determine the population and intensity of pest damage Plutella xylostella on five varieties of cabbage (Brassica oleraceae L.). The experiment was conducted in the village Waipirit in October 2012 until January 2013. The study was designed using a randomized block design with five treatments, namely cabbage as the Grand 11, KK-Cross, Green Coronet, Green Hero, and Investor. The results showed that Investors were varieties that were resistant to pests Plutella xylostella, indicated by low population groups such as eggs 2.75, 16.55 tails larvae and 1.95 tails pupae, and the low intensity of leaf damage 28.51% which was classified medium.

scholarly journals Quantification of Avoidable Yield Losses in Oilseed Brassica Caused by Insect Pests

2011 ◽  
Vol 51 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Jagdev Kular ◽  
Sarwan Kumar
Keyword(s):  
Seed Yield ◽  
Yield Loss ◽  
Insect Pests ◽  
Block Design ◽  
Maximum Yield ◽  
The Other ◽  
Yield Losses ◽  
Eruca Sativa ◽  
Mustard Aphid ◽  
Randomized Block Design

Quantification of Avoidable Yield Losses in OilseedBrassicaCaused by Insect PestsA six year field study was conducted from 2001-2002 to 2006-2007 at Punjab Agricultural University, Ludhiana, India to study the losses in seed yield of differentBrassicaspecies (B. juncea, B. napus, B. carinata, B. rapaandEruca sativa) by the infestation of insect pests. The experiment was conducted in two different sets viz. protected/sprayed and unprotected, in a randomized block design, with three replications. Data on the infestation of insect pests, and seed yield were recorded at weekly intervals and at harvest, respectively. The loss in seed yield, due to mustard aphid and cabbage caterpillar, varied from 6.5 to 26.4 per cent.E. sativasuffered the least loss in seed yield and harboured the minimum population of mustard aphid (2.1 aphids/plant) and cabbage caterpillar (2.4 larvae/plant). On the other hand,B. carinatawas highly susceptible to the cabbage caterpillar (26.2 larvae/plant) and suffered the maximum yield loss (26.4%).

scholarly journals Populasi Hama dan Musuh Alami pada Tiga Cara Budidaya Padi Sawah di Sukamandi

Agrikultura ◽  
2018 ◽  
Vol 29 (1) ◽  
pp. 35
Author(s):  
N. Usyati ◽  
Nia Kurniawati ◽  
Ade Ruskandar ◽  
Oco Rumasa
Keyword(s):  
Natural Enemy ◽  
Block Design ◽  
Rice Variety ◽  
Rice Cultivation ◽  
Limiting Factors ◽  
Pest Damage ◽  
Organic Rice ◽  
Randomized Block Design ◽  
Rice Yields ◽  
The Difference

ABSTRACTPest and natural enemy population in three different rice cultivation in Sukamandi RegionSome on limiting factors in rice production include the cultivation system and pest damage. To suppress the damage, several control techniques have been applied, such as technical culture. The aim of this study was to gain information on population and pest damage, as well as natural enemy population in three different rice cultivation systems. The study was arranged in Randomized Block Design with three treatment and 9 replications. The treatments were: 1) organic rice cultivation, 2) semi organic, and 3) farmer technique. The used rice variety was Inpari 30. The plot size was 6 m x 90 m. The variables observed included population and pest damage, natural enemy population, and rice yields. Thirthy two rice hills were observed randomly in diagonal direction, with 2 weeks interval from two weeks after transplanting until harvest. The data were analyzed by analysis of variance (Anova) and the difference among the treatments was evaluated with Duncan multiple area test at 5% level. The results showed that brown plant hoppers population on organic rice cultivation is lower than semi-organic rice cultivation and farmer technique, but there were no difference of natural enemy population among treatments. The lowest yield was obtained from the organic rice cultivation (2.67 t/ha).Keywords: Rice cultivation, Pests, Natural enemiesABSTRAKBeberapa faktor pembatas produksi padi diantaranya adalah cara budidaya dan adanya serangan hama. Untuk menekan serangan hama, beberapa teknik pengendalian telah diterapkan diantaranya adalah pengendalian secara kultur teknis (cara budidaya). Pada MT-2 tahun 2016, penelitian dengan tujuan mendapatkan informasi mengenai populasi dan serangan hama, serta populasi musuh alami pada tiga cara budidaya padi telah dilakukan di lahan kebun percobaan Balai Besar Penelitian Tanaman Padi Sukamandi. Rancangan yang digunakan adalah Rancangan Acak Kelompok (RAK) dengan tiga cara budidaya dan diulang sebanyak sembilan kali. Adapun cara budidaya yang digunakan terdiri atas:1) budidaya padi organik; 2) semi organik; 3) cara petani. Varietas yang digunakan adalah Inpari 30. Ukuran plot 6 m x 90 m. Variabel yang diamati meliputi populasi dan tingkat serangan hama, populasi musuh alami, dan hasil panen. Pengamatan dilakukan secara langsung di pertanaman pada 32 rumpun sampel secara acak diagonal dengan interval dua minggu sekali mulai umur tanaman dua minggu setelah tanam sampai menjelang panen. Data yang diperoleh dianalisis dengan analisis ragam (Anova) dan perbedaan antar perlakuan dievaluasi dengan uji wilayah berganda Duncan pada taraf 5%. Hasil penelitian menunjukkan bahwa populasi hama wereng coklat pada cara budidaya padi organik lebih rendah dibandingkan cara budidaya padi semi organik dan budidaya padi cara petani, tetapi tidak ada perbedaan populasi musuh alami pada cara budidaya padi organik, cara budidaya padi semi organik dan budidaya padi cara petani. Hasil panen terendah (2,67 t/ha) terlihat pada perlakuan budidaya padi organik.Kata Kunci: Budidaya padi, Hama, Musuh alami

scholarly journals KETAHANAN BEBERAPA AKSESI KAPAS TERHADAP HAMA PENGISAP DAUN Amrasca biguttula (ISHIDA)

2020 ◽  
Vol 13 (3) ◽  
pp. 81
Author(s):  
I G.A.A. INDRAYANI ◽  
SIWI SUMARTINI ◽  
B. HELIYANTO B. HELIYANTO
Keyword(s):  
Gossypium Hirsutum ◽  
Chemical Control ◽  
Block Design ◽  
Insect Pest ◽  
Resistant Variety ◽  
Plant Spacing ◽  
Experimental Station ◽  
Randomized Block Design ◽  
Mental Problems ◽  
Moderately Resistant

ABSTRAK<br />Amrasca biguttula (Ishida) adalah serangga hama pengisap daun<br />yang sangat potensial menurunkan produktivitas kapas. Pengendaliannya<br />secara kimiawi menimbulkan banyak masalah lingkungan, seperti<br />pencemaran dan peningkatan resistensi hama terhadap insektisida kimia<br />sintetis. Salah satu solusi dalam masalah tersebut adalah penggunaan<br />varietas tahan (resisten) yang juga merupakan bagian dari pengendalian<br />hama terpadu (PHT) pada kapas. Penelitian ketahanan beberapa aksesi<br />kapas terhadap A. biguttula (Ishida) dilakukan di Kebun Percobaan Balai<br />Penelitian Tanaman Tembakau dan Serat di Asembagus, Situbondo, mulai<br />Januari hingga Desember 2006. Tujuannya adalah untuk mengetahui<br />ketahanan beberapa aksesi kapas terhadap serangan hama pengisap daun,<br />A. biguttula. Sebagai perlakuan adalah 30 aksesi kapas yang ditanam<br />dalam plot berukuran 10 m x 3 m, dengan jarak tanam 100 cm x 25 cm,<br />satu tanaman per lobang. Setiap aksesi disusun dalam rancangan acak<br />kelompok dengan tiga kali ulangan. Parameter yang diamati adalah jumlah<br />nimfa A. biguttula per daun, jumlah bulu daun per cm 2 luas daun, dan<br />posisi bulu terhadap lamina (tegak/rebah), serta skor kerusakan tanaman.<br />Hasil penelitian menunjukkan bahwa setiap aksesi kapas berpotensi<br />terserang A. biguttula, meskipun tingkat populasi hama ini tidak<br />menunjukkan perbedaan nyata antar aksesi. Terjadi korelasi negatif (R 2 =<br />0,2425) antara jumlah bulu daun dan populasi nimfa A. biguttula dan<br />antara jumlah bulu daun dan skor kerusakan tanaman (R 2 = 0,2027).<br />Berdasarkan jumlah bulu daun, aksesi kapas yang termasuk kategori<br />sedikit berbulu dengan kriteria ketahanan sedikit tahan adalah: AC 134,<br />Stoneville 7, Fai Nai, SHR, CRDI-1, Kanesia 5, Kanesia 8, dan Kanesia 9.<br />Sedangkan aksesi lainnya termasuk kategori tidak berbulu dan peka<br />terhadap serangan A. biguttula.<br />Kata kunci : Kapas, Gossypium hirsutum, aksesi, hama, Amrasca<br />biguttula (Ishida), toleran, peka, kerusakan, Jawa Timur<br />ABSTRACT<br />Resistance of several cotton accessions to sucking insect<br />pest, Amrasca biguttula (Ishida)<br />Amrasca biguttula (Ishida) is a sucking insect pest which potentially<br />reduces cotton productivity. Its chemical control often cause environ-<br />mental problems mainly air pollution and increase of pest resistance to<br />certain chemical insecticides. One solution can be used to solve these<br />problems is by using resistant variety that is also an integral part of the<br />integrated pest management (IPM). Study on the resistance of several<br />cotton accessions to sucking insect pest, Amrasca biguttula (Ishida) was<br />conducted at the Experimental Station of the Indonesian Tobacco and<br />Fiber Crops Research Institute (IToFCRI) in Asembagus, Situbondo, East<br />Java, from January to December 2006. The objective of the study was to<br />find out the resistance of cotton accessions to sucking insect pest. Thirty<br />accessions of cotton were used as treatment and were planted in plots 10 m<br />x 3 m with plant spacing 100 cm x 25 cm, one plant per hole. Each<br />accession was arranged in a randomized block design with three<br />replications. Parameters observed were number of nymph of A. biguttula,<br />number of leaf hair, leaf hairs position (erect or lie down), and score of<br />damage. The result showed that every accession of cotton can be attacked<br />by A. biguttula although the insect population was not significantly<br />different among accessions. There is negative correlation (R 2 = 0.2425)<br />between number of leaf hair and population of A. biguttula and between<br />number of leaf hair and score of plant damage (R 2 = 0.2027). Accessions<br />that categorized as lightly hairy and moderately resistant to A. biguttula<br />were AC 134, Stoneville 7, Fai Nai, SHR, CRDI-1, Kanesia 5, Kanesia 8,<br />and Kanesia 9, while the others were categorized as glabrous and<br />susceptible to the sucking pest.<br />Key words: Cotton, Gossypium hirsutum, accession, insect pest, Amrasca<br />biguttula (Ishida), tolerant, sensitive, damage, East Jav

scholarly journals PENGARUH UKURAN BRAKTEA BEBERAPA AKSESI KAPAS TERHADAP TINGKAT SERANGAN HAMA PENGGEREK BUAH Helicoverpa armigera (HUBNER)

2020 ◽  
Vol 13 (4) ◽  
pp. 125
Author(s):  
IG.A.A. INDRAYANI ◽  
SIWI SUMARTINI
Keyword(s):  
Helicoverpa Armigera ◽  
Morphological Character ◽  
Insect Pests ◽  
Block Design ◽  
Morphological Characters ◽  
Floral Bract ◽  
Randomized Block Design ◽  
Cotton Plants ◽  
American Bollworm ◽  
Helicoverpa Armígera

<p>ABSTRAK<br />Hingga kini teknik perakitan varietas kapas tahan hama masih<br />dilakukan secara konvensional berdasarkan beberapa karakter morfologi<br />tanaman, seperti: bulu daun, daun okra, braktea berpilin, nektar, dan<br />gosipol tinggi. Karakter-karakter ini diketahui erat hubungannya dengan<br />ketahanan terhadap hama, khususnya H. armigera. Berkaitan dengan<br />serangan H. armigera pada buah, diduga ada bagian-bagian buah kapas<br />yang berkontribusi secara langsung pada serangan hama ini, misalnya<br />braktea buah. Namun demikian, besarnya pengaruh braktea terhadap<br />kerusakan buah kapas perlu dipelajari dalam upaya meminimalkan<br />kerusakan. Penelitian ini bertujuan untuk mengetahui pengaruh ukuran<br />braktea terhadap tingkat kerusakan buah oleh H. armigera pada beberapa<br />aksesi kapas. Penelitian dilaksanakan di Kebun Percobaan Balai Penelitian<br />Tanaman Tembakau dan Serat, di Asembagus, Situbondo, Jawa Timur<br />mulai bulan Januari hingga Desember 2006. Sebanyak 18 aksesi dari 50<br />aksesi kapas dengan berbagai variasi ukuran braktea digunakan sebagai<br />perlakuan. Setiap perlakuan (aksesi) disusun dalam rancangan acak<br />kelompok (RAK), dengan tiga kali ulangan. Lima tanaman kapas dari<br />masing-masing aksesi ditentukan secara acak, dan sebanyak 5 buah kapas<br />muda (diameter ± 4 cm) dipetik dari masing-masing tanaman sampel,<br />kemudian dibawa ke laboratorium untuk diukur luas braktea dan buahnya.<br />Selain itu dilakukan pula pengamatan kerusakan buah dan hasil kapas<br />berbiji di lapang. Hasil penelitian menunjukkan bahwa ukuran braktea<br />berkorelasi positif dengan tingkat kerusakan buah (R 2 = 0,9014), sehingga<br />braktea berukuran besar dan lebar serta menutupi buah secara total<br />berpotensi mengalami kerusakan akibat serangan H. armigera lebih tinggi<br />dibanding braktea berukuran kecil dan sempit. Ukuran panjang dan lebar<br />braktea pada 18 aksesi kapas bervariasi antar aksesi dan masing-masing<br />berkorelasi positif dengan luas (R 2 = 0,876; R 2 = 0,894). Hasil penelitian<br />ini dapat dimanfaatkan dalam merakit varietas tahan hama, dan<br />kombinasinya dengan karakter-karakter morfologi kapas yang sudah ada<br />untuk menghasilkan varietas kapas baru dengan tingkat ketahanan yang<br />lebih tinggi terhadap hama penggerek buah H. armigera.<br />Katakunci : Braktea, Helicoverpa armigera, aksesi kapas, karakter<br />morfologi.</p><p><br />ABSTRACT<br />Effects of bract size of several cotton accessions to<br />American bollworm injury level<br />Conventional  method  by  crossing  technique  based  on<br />morphological characters of plant is now still used in providing resistant<br />varieties of cotton against insect bollworms. A number of genetic<br />characters are now available and have been studying for their assosiation<br />with insect pests resistance such as hairiness, okra leaf, frego bract,<br />nectariless, and high gossypol. Regarding to boll damage by H. armigera,<br />it can be mentioned that there are many other morphological characters of<br />cotton attributable to bollworm damage, such as floral bract. As a part of<br />boll, it is estimated that bracts assosiated with bollworm attacked due to<br />their larger size compared with boll size. Objective of the study was to find<br />out the effect of bract size in relation to bollworm damage on cotton<br />accessions. The study was conducted at Experimental Station of<br />Indonesian Tobacco and Fiber Crops Research Institute in Asembagus,<br />Situbondo, East Java from January to December 2006. Eighteen of fifty<br />cotton accessions were used as treatment and they were arranged in<br />Randomized Block Design (RBD) with three replications. Five randomly<br />cotton plants from each accession and five young bolls were sampled<br />from the selected plant with about 4 cm of diameter were brought in the<br />laboratory to collect information on bract and boll sizes. Bollworm<br />damage was determined by counting the damaged bolls in the field as well<br />as the seed cotton yield. Result showed that bract size was positively<br />correlated with boll damage (R 2 = 0.9014). Higher damaged bolls occured<br />on bolls which is covered completely by bracts. There is variation between<br />length and wide size of bracts among cotton accessions and both showed<br />positive correlation to bract area (R 2 = 0.876; R 2 = 0.894). Based on this<br />study, higher resistance of cotton variety against H. armigera will<br />possiblly be provided through combination between bract size and any<br />other morphological characters of cotton.<br />Key words : Floral bract, Helicoverpa armigera, cotton accession,<br />morphological character</p>

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