Keragaman morfologi dan genetik serta derajat kompetisi beberapa aksesi gulma Echinochloa crus-galli (L.) Beauv. terhadap tanaman padi sawah

Abstract

Weed disturbance is an important issue in rice production in Indonesia. Echinochloa crus-galli (L.) Beauv. is the most dominant weed in rice leading to loss of production. The research aims to analyze the morphology and genetic diversity of weeds accession E. crus-galli from West Java and degree of competition of E. crus-galli to rice. Research was carried out by using several steps, i.e : (1) Preliminary experiments on growth and production of rice with E. crus-galli weed population levels originating from three locations, (2) Morphological and genetic evaluation, (3) Identification of potential weed allelophaty E. crus-galli accession, (4) Study effect of E. crus-galli accession on the growth and rice production (greenhouse experiments), (5) Effects of accession and population rate of E. crus-galli on the growth and rice production (field trial), (6) Estimation of degree competition of E. crus-galli by the replacement series method, (7) Study of physiology competition between rice with weeds. Results showed that E. crus-galli accession from West Java exhibited morphological and genetic diversity. Accession from different geographical locations showed differences in morphology. The diversity of morphology is presumably due to the phenotypic plasticity and adaptation ability of E. crus-galli accessions. Cluster analysis based on SSR molecular markers produced four sub-groups with similarity coefficient of 0.86, with most of the group clustered in geographic zones of western West Java and northen. This genetic diversity might be caused by the movement of genetic material through harvest or through irrigation, isolation distance, and the possibility of mutation. E. crus-galli accessions had the potential allelophaty based on inhibit of radicle and plumula growth of rice. Based on the potential allelophaty, the accessions clustered to six groups at 0.72 similarity coefficient. Each accession of E. crus-galli showed a potential difference in reducing the growth and yield of rice plants. This ability is probablt related to morphological characteristics and allelophatyic potential. Accession K6 from Karawang showed the highest ability to suppress the growth and production of rice plants. E. crus-galli weed had a higher degree of competition to rice plants when the weed population was higher than the population of rice plants. Based on the value of aggressiveness, E. crus-galli competed stronger than rice when the population of rice plants and weeds is equal or weed population was higher than that of rice population. Each rice variety had a different response to population levels of E. crus-galli. The competition between rice plants with a E. crus-galli inhibited the physiological process of rice plant.

Salah satu masalah penting dalam upaya peningkatan produksi padi di Indonesia adalah menurunkan gangguan gulma selama pertumbuhan. Echinochloa crus-galli (L.) Beauv. merupakan gulma dominan pada tanaman padi sawah yang menyebabkan kehilangan hasil produksi. Penurunan produksi tersebut disebabkan oleh adanya kompetisi antara gulma dan tanaman padi terhadap sumberdaya yang tersedia. Penelitian bertujuan untuk : (1) menganalisis keragaman morfologi dan genetik aksesi gulma E. crus-galli asal Jawa Barat, (2) Mengidentifikasi potensi alelopati aksesi gulma E. crus-galli asal Jawa Barat, (3) Mempelajari pengaruh aksesi dan tingkat populasi E. crus-galli terhadap pertumbuhan dan produksi padi sawah, (4) Mengkaji derajat kompetisi gulma E. crus-galli dengan metode replacement series, dan (5) Mempelajari fisiologi kompetisi antara padi dengan gulma E. crus-galli. Penelitian dilakukan dengan beberapa tahapan antara lain : (1) Percobaan pendahuluan tentang Pertumbuhan dan Produksi Padi pada berbagai Tingkat Populasi Gulma E. crus-galli yang Berasal dari Tiga Lokasi, (2) Keragaman Morfologi dan Genetik Aksesi E. crus-galli asal Jawa Barat, (3) Identifikasi Potensi Alelopati Aksesi Gulma E. crus-galli Asal Jawa Barat, (4) Kajian Pengaruh Aksesi Gulma E. crus-galli terhadap Pertumbuhan dan Produksi Padi (Percobaan Rumah Kaca), (5) Kajian Pengaruh Aksesi dan Tingkat Populasi Gulma E. crus-galli terhadap Pertumbuhan dan Produksi Padi (Percobaan Lapangan), (6) Pendugaan Derajat Kompetisi Gulma E. crus-galli dengan Metode Replacement Series, (7) Kajian Fisiologi Kompetisi antara Padi dengan Gulma.