PATOGENISITAS BEBERAPA ISOLAT CENDAWAN TERBAWA BENIH KAKAO HIBRIDA
Authors: BAHARUDIN BAHARUDIN , PURWANTARA A. , ILYAS S. , SUHARTANTO M.R. 
Published: June 2020

<p>ABSTRAK<br />Benih kakao hibrida diketahui dapat membawa beberapa mikroba<br />yang bersifat patogenik dan menurunkan mutu benih. Penelitian bertujuan<br />untuk mengetahui pengaruh beberapa isolat cendawan terbawa benih<br />terhadap penurunan viabilitas benih dan vigor bibit kakao hibrida.<br />Penelitian dilakukan di Kebun Benih Pusat Penelitian Kopi dan Kakao<br />Indonesia, Jember, Laboratorium Mikrobiologi dan rumah kaca Balai<br />Penelitian Bioteknologi Perkebunan Indonesia, Bogor, pada bulan Juli<br />sampai November 2008. Penelitian menggunakan 13 cendawan terbawa<br />benih kakao hibrida. Benih diperoleh dari persilangan buatan antara kakao<br />TSH 858 dengan Sca 6. Penelitian menggunakan model Rancangan Acak<br />Lengkap dengan 4 ulangan. Inokulasi patogen pada benih kakao dilakukan<br />dengan cara merendam benih di dalam suspensi patogen dengan kerapatan<br />10 6 spora/ml selama 30 menit. Selanjutnya benih ditanam pada media pasir<br />steril dalam boks plastik ukuran 30 x 30 cm, menurut rancangannya.<br />Setiap perlakuan diulang 4 kali. Parameter yang diamati adalah daya<br />berkecambah, indeks vigor, kecepatan tumbuh relatif, kecepatan<br />berkecambah T 50 , laju pertumbuhan kecambah, jumlah daun, tinggi bibit,<br />panjang akar, jumlah akar dan kematian benih. Data dianalisis dengan<br />ANOVA dan dilanjutkan dengan uji Jarak Berganda Duncan. Hasil<br />penelitian menunjukkan bahwa ke-13 spesies cendawan bersifat patogenik<br />pada benih kakao hibrida. Cendawan patogen terbawa benih yang bersifat<br />patogenik adalah Aspergillus flavus, A. ochraceus, Cladosporium<br />herbanum, Curvularia geniculata, Fusarium oxysporum, Phoma<br />glomerata dan Macrophoma sp. Cendawan patogen tersebut dapat<br />menurunkan daya berkecambah 20-40%, indeks vigor 30-47%, kecepatan<br />tumbuh relatif 13-45%, dan meningkatkan kecepatan perkecambahan<br />(T 50 menurun) dari 0,62-7,36 hari. Ke-13 isolat patogen dapat<br />menyebabkan kematian benih 29-52% dibanding kontrol. Ke-13 isolat<br />patogen juga menginfeksi bagian tanaman seperti kotiledon, daun, batang<br />dan akar bibit kakao, namun hanya Phoma glomerata dan Macrophoma<br />sp. yang menurunkan tinggi bibit, jumlah daun, jumlah dan panjang akar<br />secara nyata. Tujuh dari 13 isolat cendawan patogen terbawa benih tidak<br />hanya menurunkan viabilitas dan vigor benih kakao hibrida tetapi juga<br />dapat berkembang pada bibit sehingga perlu penanganan benih secara dini.<br />Kata kunci: benih hibrida, patogen terbawa benih, viabilitas, vigor benih,<br />Theobroma cacao</p><p>ABSTRACT<br />In 2009 revitalization of cacao plantations in Indonesia required 168<br />million seeds. Distribution of low quality and infected seeds leads to huge<br />losses and in a long term will destruct cultivation of cacao. Seed-borne<br />pathogens of infected cacao hybrid seeds are dangerous because they may<br />reduce physiological qualities of the seeds. The study aimed at<br />determining the effect of several isolates of seed borne fungi on the<br />viability and vigor of hybrid cacao seeds as well as growth of the<br />seedlings. The study was conducted at the Seed Garden Indonesian Coffee<br />and Cacao Research Center in Jember, Microbiology Laboratory and glass<br />house of Biotechnology Research Institute for Estate Crops of Indonesia,<br />Bogor, from July to November 2008. The study used 13 seed-borne fungi<br />in hybrid cacao. The cacao seeds were obtained from hand pollinated<br />crossing between TSH 858 with Sca 6. The experiment was arranged using<br />Completely Randomized Design with four replicates. Cacao seeds were<br />inoculated by immersing them for 30 minutes in the spore suspension of<br />13 isolates of seed-borne fungi CTB at a density of 10 6 spores/ml. After<br />inoculation, the seeds were planted on sterile sand in a plastic box (30 x 30<br />cm). Parameters observed were germination rate, vigor index, KCT-R T 50<br />rate of seedling growth, leaf number, seedling height, root length, root<br />number, and level of pathogenicity. Data were analyzed by ANOVA<br />followed with Duncan's Multiple Test. The results showed that the 13<br />species of seed-borne pathogens were in hybrid cacao seeds with varying<br />pathogenicity. The most pathogenic fungi were Aspergillus flavus,<br />Aspergillus ochraceus, Cladosporium herbanum, Curvularia geniculata,<br />Fusarium oxysporum, Phoma glomerata, and Macrophoma sp. Seed borne<br />pathogenic fungi had the ability to reduce seed germination of 20-40%,<br />vigor index of 30-47%, relative growth rate of 13-45%, and delayed<br />germination speed (T 50 decreases) from 0.62 to 7.36 days. Seed borne<br />pathogens caused (29-52%) death seed compared to control. All that 13<br />isolates of seed-borne pathogens infected plant tissues such as cotyledons,<br />leaves, stems, and roots of cacao seedlings, but only isolates of Phoma<br />glomerata and Macrophoma sp. which lowered the height of seedlings,<br />leaf number, root number and length. The study indicated that infection of<br />seed-borne pathogens on cacao seed hybrid can cause seed death.<br />Therefore, seeds should be handled properly.<br />Key words: hybrid seeds, seed borne pathogens, viability, seed vigor,<br />Theobroma cacao</p>