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

<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>

Vriesea mourae (Bromeliaceae), a new critically endangered species from Serra da Bocaina, southeastern Brazil

A new, critically endangered taxon, Vriesea mourae, endemic to the Serra da Bocaina mountains in southeastern Brazil, is described. We provide data on its conservation status, etymological and taxonomic notes, photographs, and illustrations. The taxon is morphologically similar to V. warmingii, differing mainly in the shorter blade, diameter of peduncle and rachis, inflorescence length, floral bract shape and color, sepal shape, petal shape, length, and color.

Platanthera guangdongensis and P. zijinensis (Orchidaceae: Orchideae), two new species from China: Evidence from morphological and molecular analyses

Two new Platanthera (Orchidinae, Orchideae, Orchidoideae) species, P. guangdongensis and P. zijinensis, from the Guangdong Province in China are described and illustrated based on morphological and molecular analyses. Platanthera guangdongensis is leafless and resembles P. fujianensis, but it differs in terms of the shorter and/or smaller inflorescence, floral bract, dorsal sepal, lateral sepal, petal, and ligulate lip. Platanthera zijinensis is morphologically similar to P. minor, but it differs by the ovate-oblong to ovate floral bract, colour of flower, ovate dorsal sepal, oblong lateral sepal, ovate-oblong lip, and curved forward spur. The phylogenetic analyses based on nuclear ribosomal ITS and chloroplast (rbcL and matK) sequence data support that P. zijinensis and P. guangdongensis being sisters to each other and genetically sister to P. minor. The chloroplast rbcL of P. guangdongensis is a pseudogene, supporting its characterization as a holomycotrophic orchid.

Liparis meihuashanensis, a new orchid species from Fujian, China: Evidence from morphological and molecular analyses

A new orchid species, Liparis meihuashanensis, from Fujian, China is described and illustrated based on morphological and molecular analyses. Detailed morphological comparisons indicate that L. meihuashanensis is similar to L. auriculata and L. pauliana, but it can be distinguished from them by the shorter inflorescence, triangular floral bract, and a lip with a truncate-emarginate and mucronate apex and 2 small subconical calli on contracted base. Molecular analyses based on nuclear ITS and plastid matK DNA sequence data support the L. meihuashanensis as a distinct species.

A new species of Brachionidium (Pleurothallidinae: Orchidaceae) from the high montane forest in the Central Jungle of Peru

A new species of Brachionidium was found on the highest mountains of the Central Jungle of Peru, on a wet Puna forest at 3470 m altitude. This species is similar to B. loxense and B. diaphanum but can be distinguished by its elliptic leaves with petioles 3–4 mm long; the short erect floral peduncle 2–3 mm long; the pink translucent sepals, red-wine toward the base; the floral bract spatuliform 15 × 5 mm; lip red-wine, bimarginated, trapezoidal, small, fleshy, obtuse acuminate, slightly prolonged lateral lobes antrorse and straight with a strongly pubescent cordate callus, split towards the apex.

Lomandra marginata (Asparagaceae), a shy-flowering new species from south-western Australia

Lomandra marginata T.D.Macfarl. & Conran is described as a new species and illustrated by photographs and a distribution map. Recognised initially from vegetative plants during a biological survey at Lochada Station, it was realised subsequently that the species is widespread from Geraldton to Corrigin. However, it apparently flowers only occasionally under favourable conditions, so earlier collections were mostly vegetative. Lomandra marginata is placed in L. series Sparsiflorae on the basis of possessing a narrow floral bract that does not encircle the pedicel and a bracteole, when present, offset rather than opposite the bract. It has distinctive membranous leaf margins resembling those of the related genus Chamaexeros and the longest pedicels in the genus, mostly 10–16mm long, on which are borne white flowers resembling those of L. effusa (Lindl.) Ewart. Although L. effusa is the most similar species in flower and inflorescence and is also a member of L. series Sparsiflorae, it differs vegetatively by having distinctly two-toothed leaf tips.

Anatomy of the floral, bract, and foliar nectaries of Triumfetta semitriloba (Tiliaceae)

Triumfetta semitriloba Jacq. (Tiliaceae) is a tropical weedy species with floral nectaries and glands located at the margins of the leaves. The objectives of this work were to describe the anatomy of these secretory structures and to analyze their exudates. Sucrose, glucose, and fructose were identified in the product released by these secretory structures, characterizing them as nectaries. The nectaries of T. semitriloba are of a specialized type; a secretory epidermis comprised of pluricellular and multiserial nectariferous trichomes covers a nectariferous parenchyma, vascularized by phloem and xylem. A mass of phenolic compounds occurs in the head cells of the nectariferous trichomes of the foliar and bract nectaries; however, it is absent in trichomes of the floral nectary. The leaf and bract nectaries differed from those from flowers in their length and diameter. Structural features of the nectaries of T. semitriloba are typical of other taxa of the Malvales.Key words: foliar anatomy, histochemistry, Malvales, nectaries, Tiliaceae, Triumfetta semitriloba.

Genetics of Mutations Affecting the Development of a Barley Floral Bract

Two groups of mutants that affect the morphology of the lemma, a floral bract of barley, are described. The first comprises phenotypes associated with mutant alleles of calcaroides loci. On the lemma of these mutants, a well-organized neomorphic structure is formed, termed the sac. We provide a morphological description of wild-type (WT) and mutant lemmas, based on scanning electron microscopy (SEM), showing that both consist of similar tissues, but that the mutant is characterized by reversed growth polarity. The sac is a unique structure among grasses, and it is remarkable that recessive mutations at five different genetic loci lead to the same organ. The second group of mutants carry recessive alleles of two leafy lemma genes, both of which are necessary to cause the transformation of the lemma into a structure having all characteristics of a vegetative leaf, as shown by SEM analysis. The presence of sheath, blade, and ligule in the mutant lemma suggests that wild-type lemma development is interrupted at a leaf-like stage. The genes cal a, b, C, d, 23, lel1, and lel2 have now been mapped at precise positions on linkage groups 2, 7, 7, 3, 7, 5, and 7, respectively. The mutants considered in this article are unaffected in other floral organs. A model for lemma development is suggested.