Resistensi terhadap Hama Wereng Batang Coklat dan Toleransi Kekeringan pada Galur-Galur Dihaploid Padi Sawah Berdaya Hasil Tinggi

Abstract

Padi merupakan bahan pangan pokok sebagian besar penduduk di dunia, terutama di Indonesia. Produksi padi nasional terus mengalami penurunan seiring dengan penurunan luas panen yang disebabkan oleh alih fungsi lahan. Penurunan produktivitas padi yang signifikan juga disebabkan oleh perubahan iklim dunia. Perubahan iklim menyebabkan lahan-lahan pertanian mengalami cekaman biotik seperti serangan hama penting yaitu wereng batang coklat (WBC) dan cekaman abiotik seperti kekeringan. Hal ini memerlukan upaya yang ramah lingkungan dengan menanam varietas padi unggul yang berdaya hasil tinggi, tahan WBC dan toleran kekeringan. Perakitan varietas padi unggul berdaya hasil tinggi, tahan WBC dan toleran kekeringan dapat dilakukan dengan teknik kultur antera untuk mempersingkat waktu menghasilkan galur murni. Tujuan umum penelitian ini ialah untuk mendapatkan galur-galur dihaploid padi sawah berdaya hasil tinggi, tahan terhadap hama WBC dan toleran kekeringan. Serangkaian percobaan dilakukan untuk mencapai tujuan tersebut, mulai dari uji daya hasil pendahuluan (UDHP) galur-galur dihaploid (DH) padi yang bertujuan untuk menyeleksi galur-galur DH berdasarkan seleksi indeks dan karakter agronomi. UDHP dilakukan terhadap 60 galur DH, 5 galur/varietas pembanding yaitu galur elit KP4, galur elit BioNL 6-1, varietas Inpari-45, Ciherang Malaka dan Inpari-42. Hasil penelitian menunjukkan bahwa terdapat 29 galur yang memiliki karakter agronomi yang baik pada produktivitas (4,93-6,77 ton ha-1), jumlah anakan produktif (12,7-19,4 anakan), jumlah gabah total (154,9-262,1 biji), dan persentase gabah isi (53,2-85,5%). Galur-galur DH padi terpilih selanjutnya diuji daya hasil lanjutan. Uji daya hasil lanjutan (UDHL) galur-galur DH padi dilakukan di 3 lokasi (Bogor, Indramayu, Malang), bertujuan untuk memperoleh informasi tentang penampilan agronomis, stabilitas hasil dengan cara menyeleksi galur-galur DH yang memiliki produktivitas tinggi di tiga lokasi. Pengujian ini menggunakan 29 galur DH padi terseleksi dan tiga varietas pembanding yaitu Inpari 42, Inpari 18 dan Bioni 63 Ciherang Agritan. Analisis stabilitas dilakukan di 3 kondisi lingkungan berbeda untuk mengetahui hasil tinggi dan stabil. Berdasarkan seleksi stabilitas metode Kang, Francis dan Kannenberg, terdapat 8 galur dengan produktivitas tinggi dan stabil yaitu WH03 (7,82 ton ha-1), WH07 (7,66 ton ha-1), WH20 (7,39 ton ha-1), WH21 (7,38 ton ha-1), WH37 (7,32 ton ha-1), WH49 (7,38 ton ha-1), WH52 (7,21 ton ha-1) dan WH54 (7,23 ton ha-1). Hasil seleksi indeks pembobotan menunjukkan 12 galur DH padi memiliki nilai indeks positif dan karakter agronomi lebih baik di tiga lokasi dibandingkan dengan varietas pembanding Bioni 63 Ciherang Agritan dan Inpari 18. Uji ketahanan WBC pada galur-galur DH padi dilakukan untuk seleksi tingkat ketahanan galur-galur DH padi terhadap WBC biotipe 1, 2, 3 dan populasi Cilacap. Pengujian ini menggunakan 25 galur DH, varietas unggul pembanding Inpari 18 dan Bioni 63 Ciherang Agritan dan varietas pembanding WBC yaitu varietas TN1 (kontrol rentan), varietas PTB 33 dan IR 72 (kontrol tahan). Hama WBC yang digunakan yaitu biotipe 1, 2, 3 dan populasi Cilacap. Pengujian dilakukan di bak skrining ukuran panjang 2 m x lebar 80 cm x tinggi 25 cm. Hasil penelitian menunjukkan bahwa terdapat 9 galur DH padi yaitu WH03, WH04, WH06, WH07, WH08, WH09, WH16, WH17 dan WH20 yang memiliki kriteria tahan dan agak tahan terhadap WBC biotipe 1, 2, 3 dan populasi Cilacap. Uji marka molekuler SSR dilakukan dengan tujuan memverifikasi hasil uji biologi dan memperoleh informasi galur-galur DH padi yang mengandung gen ketahanan WBC (bph4 dan Bph6) melalui uji molekuler SSR. Materi genetik yang digunakan 25 galur DH, varietas pembanding WBC yaitu TN 1 (kontrol rentan), Babawee (bph4), Bioni63 Ciherang Agritan (Bph6), Swarnalata (Bph6) dan tetua persilangan (KP4, BioNL 6-1, Inpari 45 dan Ciherang Malaka). Hasil penelitian menunjukkan 25 galur DH yang diuji terindikasi mengandung gen bph4 dan 12 galur DH diantaranya terindikasi mengandung gen Bph6. Uji toleransi kekeringan dilakukan di rumah kaca untuk mengidentifikasi galur-galur DH padi yang toleran kekeringan melalui uji kekeringan fase bibit. Uji toleransi kekeringan menggunakan 25 galur DH padi, dua pembanding varietas unggul (Inpari 18 dan Bioni 63 Ciherang Agritan) dan dua varietas pembanding untuk cekaman kekeringan yaitu varietas Salumpikit (kontrol toleran) dan IR 20 (kontrol sensitif). Berdasarkan nilai skoring penggulungan daun, daun mengering dan daya tumbuh kembali (recovery) dilakukan seleksi indeks. Hasil seleksi indeks menunjukkan terdapat 13 galur yang memiliki nilai indeks positif sama dengan varietas Salumpikit. Galur-galur tersebut memiliki kriteria toleran terhadap cekaman kekeringan. Rekapitulasi dari berbagai pengujian berdasarkan analisis heatmap clustergram menghasilkan 9 galur DH padi sawah yang memiliki produktivitas tinggi, tahan terhadap hama WBC dan toleran kekeringan. Galur-galur tersebut ialah galur WH03, WH04, WH06, WH07, WH08, WH09, WH17, WH20 dan WH21. Galur-galur DH padi tersebut lebih baik dari varietas pembanding yaitu varietas Inpari 18 dan Bioni 63 Ciherang Agritan dengan rata-rata produktivitas di tiga lokasi sebesar 7,46 ton ha-1, berkisar antara 7,03-7,82 ton ha-1.

Rice is the staple food for most of the world's population, especially in Indonesia. Rice production continues to decline in line with the decline in harvested area as caused by land conversion and a significant decline in rice productivity as caused by global climate change. The change has caused agricultural lands to experience biotic stress, i.e attacks by important pests such as brown planthoppers (BPH) and abiotic stresses such as drought. This requires environmentally friendly superior rice varieties that are high yielding, BPH resistant, and drought-tolerant. The development of superior rice varieties with high yields, BPH resistance and drought tolerance can utilize anther culture techniques to shorten the time to produce pure lines. The general aim of this study was to obtain doubled haploid lines of lowland rice with high yields, BPH resistance, and drought tolerance. A series of experiments were carried out to achieve this goal, starting from a preliminary yield trial of doubled haploid (DH) rice lines produced by anther culture. The objective was to select DH rice lines based on selection indices and agronomic characteristics. Preliminary yield trial was carried out on 60 DH lines and five check lines/varieties, namely KP4, BioNL 6-1, Inpari-45, Ciherang Malaka, and Inpari-42. The results of the research showed that there were 29 lines that had good agronomic characteristics, namely productivity (4.93-6.77 tons ha-1), number of productive tillers (12.7-19.4 tillers), total grain number (154.9 -262.1 seeds), and the percentage of filled grain (53.2-85.5%). The selected DH lines were evaluated further in advanced yield trials. Advanced yield trials (AYT) of DH rice lines were conducted in three locations (Bogor, Indramayu and Malang). The objective was to obtain information on agronomic performance, yield stability, and to select doubled haploid lines that have high productivity in three locations. AYT used 29 selected DH rice lines and three check varieties, namely, Inpari 42, Inpari 18, and Bioni 63 Ciherang Agritan. Stability analysis was carried out under three different environmental conditions to determine high and stable yields. Based on two stability analysis Kang, Francis and Kannenberg, it was shown that there were 8 lines with high and stable yields, namely WH03 (7.82 tons ha-1), WH07 (7.66 tons ha-1), WH20 (7.39 tons ha-1), WH21 (7.38 tons ha-1), WH37 (7.32 tons ha-1), WH49 (7.38 tons ha-1), WH52 (7.21 tons ha-1) and WH54 (7.23 tons ha-1). The result of the weighted index selection showed that 12 DH lines had positive index values and better agronomic characteristics compared to the check varieties Bioni 63 Ciherang Agritan and Inpari 18. A BPH resistance evaluation on DH rice lines was carried out to select and determine the level of resistance of DH lines to BPH biotypes 1, 2, and 3 and the Cilacap population in the greenhouse. Twenty five DH lines, the superior check varieties Inpari 18 and Bioni 63 Ciherang Agritan, and the BPH check varieties namely the TN 1 variety (susceptible check), PTB 33 and IR 72 (resistant check) were evaluated. The BPH pests used were biotypes 1, 2, and 3 and the Cilacap population. Evaluation was conducted in the box of 2 m long x 80 cm wide x 25 cm high. The results showed that there were nine DH rice lines, namely WH03, WH04, WH06, WH07, WH08, WH09, WH16, WH17, and WH20, which met the criteria resistant and moderate resistant to BPH biotypes 1, 2, 3, and the Cilacap population. The SSR molecular marker test was carried out in Plant Molecular Biology Laboratory IPB. The objective of the study was to verify bioassay test and identify DH rice lines containing BPH resistant genes (bph4 and Bph6) using SSR markers. The genetic material used were 25 DH lines, BPH check varieties, namely TN 1 (susceptible check), Babawee (bph4), Bioni63 Ciherang Agritan (Bph6), Swarnalata (Bph6) and parent crosses (KP4, BioNL 6-1, Inpari 45, and Ciherang Malaka). The results of this study showed that 25 DH lines tested contained the bph4 gene and 12 DH lines also contained the Bph6 gene. A drought tolerance evaluation was carried out in BBPSI Biogen greenhouse. The objective of the study was to identify drought tolerant DH rice lines at a seedling phase. The drought tolerance evaluation used 25 DH lines, two check varieties (Inpari18 and Bioni 63 Ciherang Agritan) and two drought check varieties namely Salumpikit variety (tolerant check) and IR 20 (sensitive check). Index selection was carried out based on the scoring values of leaf rolling, leaf drying, and recovery. The results of index selection showed that 13 lines had the same positive index value as the Salumpikit variety. These lines have criteria for tolerance to drought stress. The recapitulation of various tests and clustergram heatmap analysis yielded nine DH rice lines with high productivity, resistant to BPH and tolerant to drought. The lines were WH03, WH04, WH06, WH07, WH08, WH09, WH17, WH20 and WH21. These lines were better than the check varieties, namely the Inpari 18 and Bioni 63 Ciherang Agritan. They had a range of productivities in three locations 7.03-7.82 tons ha-1 with an average of 7.46 tons ha-1.