PEWARISAN SIFAT HERMAPRODIT DAN KONTRIBUSINYA TERHADAP DAYA HASIL PADA JARAK PAGAR (Jatropha curcas L.) - HARTATI, RR. SRI; SUDARSONO, SUDARSONO (Pusat Penelitian dan Pengembangan Perkebunan)
ABSTRAKKontribusi sifat hermaprodit terhadap daya hasil tanaman jarakpagar belum banyak diketahui. Tujuan penelitian adalah mengetahui peranbunga hermaprodit terhadap daya hasil dan mekanisme pewarisannya.Penelitian dilakukan terhadap 60 genotipe jarak pagar di Kebun PercobaanBalittri Sukabumi. Penelitian dilaksanakan mulai bulan Mei 2007 sampaidengan Juli 2010. Jarak tanam 2 m x 2 m, menggunakan 2,5 kg pupukkandang + 20 g Urea + 20 g SP 36 + 10 g KCl per tanaman. Penelitianterdiri dari (1) evaluasi tipe bunga jarak pagar dan (2) pewarisan sifathermaprodit dan kontribusinya terhadap daya hasil. Hasil evaluasimenunjukkan bahwa delapan dari 60 genotipe jarak pagar yang dievaluasimerupakan tanaman tri-monoecious yang menghasilkan bunga jantan,bunga betina, dan bunga hermaprodit, 52 lainnya merupakan tanamanmonoecious yang hanya menghasilkan bunga jantan dan bunga betina.Karakter yang dimiliki oleh delapan genotipe tri-monoecious yangdievaluasi adalah lebih lambat berbunga (mulai berbunga pada umur 120-274 hari) dan berdaya hasil rendah sampai sedang (jumlah buah 23-228per tanaman pada tahun pertama). Kemunculan bunga hermaprodit tidakterjadi sepanjang tahun, tetapi lebih dominan pada tanaman berumur enambulan. Persentase bunga hermaprodit berkisar 6,25-53% dari total bungayang dihasilkan. Persentase fruitset pada tandan bunga hermaprodit lebihtinggi dibanding tandan bunga non-hermaprodit, dengan tingkatkeberhasilan rata-rata 80% (kisaran 56-100%). Pada tandan bunga yangtidak menghasilkan bunga hermaprodit, buah jadi rata-rata sebesar 50%(kisaran 11-100%). Daya hasil tanaman jarak pagar ditentukan olehgenetik tetua. Bunga hermaprodit diwariskan oleh tetua betina maupuntetua jantan. Gen pengendali sifat hermaprodit diduga adalah gensederhana yang bersifat dominan.Kata kunci: Jatropha curcas, monoecious, tri-monoecious, bungahermaprodit, fruit setABSTRACTHermaphrodite character has been reported in physic nut, its roleand contribution to production process especially to the yield has not beeninvestigated. The objectives of this research were to evaluatehermaphrodite flowers contribution on yield and their mechanisminheritance. The evaluation was conducted at the Experimental Station ofBalittri Sukabumi from May 2007 to July 2010. The spacing was 2 m x 2m with 2,5 kg manure + 20 g Urea + 20 g SP 36 + 10 g KCl/plant. Theexperiment consisted of (1) evaluation of flower type of physic nut and(2) hermaphrodite inheritance and their contribution on yield. Results ofthe experiment indicated eight from 60 physic nut genotypes were tri-monoecious which were capable on producing male, female, andhermaphrodite flowers while as the rest (52 genotypes) were monoeciouswhich produced only male and female flowers. The tri-monoecious weregenerally late flowering (120-274 days after planting) and low to mediumyield (producing 23-228 fruits per plant in the first year). Hermaphroditeflowers generally occurred six months after planting at the amount rangedfrom 6,25-53% of total flowers. Fruit set of inflorescences havinghermaphrodite flowers was higher, average of 80% (ranged from 56-100%) than those with female and male flowers, average of 50% (rangedfrom 11-100%). Yield of physic nut was affected by the genetic potentialof their parents rather than hermaphrodite character. Hermaphrodite flowercharacter was inherited by both female and male parents and might becontrolled by simple-dominant gene.Key words: Jatropha curcas, monoecious, tri-monoecious, hermaphroditeflower, fruit set