Most of Indonesian red rice is not grown in dry land. New varieties could be breeded through mutation breeding. This research objective was to evaluate the selection strategy of drought tolerant on red rice. The study was conducted on Ultisol soil in Bangka Belitung Province, Indonesia, in February 2012-February 2015. It consisted of three activities, selection M5, evaluation of selected M5 and evaluation of drought critical period on selected M6. Mutant of M5 was selected and evaluated with polyethylene glycol (PEG) -0.5 MPa and less of soil moisture. Selected M6 was evaluated to observe a critical period of drought stress. Evaluation with PEG produces five superior mutants that more vigor than the elders. Selection on low humidity shows that M5-GR150-1-9 produces higher filled grain and weight filled grain than other mutants and elders. The selected red rice line M5-GR150-1-9-13, has a better tolerance towards drought than its control. It could be obtained such mutant lines which have a high yield, early maturing and drought tolerant from the result of six generations gamma irradiation mutant selection.

Accession of red rice does not have the traits of early maturity, drought tolerance and high yield. Mutation is needed to obtain the desired genetic resources. Gamma-ray irradiation is the right method because it was proved capable of producing hundreds of new varieties, which are better than the previous. This study aimed to identify the improvement of early maturity and drought tolerance of red rice mutant to gamma ray irradiation results. The research materials are M4, M5 and M6 strain, which are derived from the Bangka's accession local red rice (Celak Madu, Ruten Puren and radix). The three accession seed have been treated with gamma-ray irradiation doses of 150, 200 and 250 Gray. The results showed gamma ray irradiation dose of 150 Gray and 200 Gray to red rice accession can form a mutant with the character of harvesting time less than 115 days after planting and was more drought tolerant than the previous. M6-GR150-1-9-13 strain was selected as a candidate for early maturity, drought tolerant and high yield mutant.

Pengembangan tebu di Indonesia saat ini sebagian besar terdapat di lahan kering, oleh karena itu perakitan varietas toleran kekeringan merupakan suatu langkah yang bijaksana, karena merupakan pendekatan yang paling mudah aplikasinya dan ekonomis. Saat ini telah diperoleh beberapa genotipe harapan tebu untuk lahan kering. Penelitian ini bertujuan unuk mengkaji daya hasil genotipe tebu hasil persilangan untuk pengembangan di lahan kering. Penelitian dilaksanakan di Kebun Percobaan Ngemplak, Pati dari bulan Januari sampai dengan November 2017, menggunakan 8 genotipe tebu yang berpotensi toleran kering dibandingkan dengan 2 varietas PS 864 dan Kenthung) sebagai pembanding. Penelitian disusun dalam Rancangan Acak Kelompok yang diulang tiga kali. Petak yang digunakan berukuran 5 m x 10 m, serta jarak pusat ke pusat (PKP) 1 m, atau 10 juring dengan panjang masing-masing 5 m. Parameter yang diamati meliputi tinggi tanaman, diameter batang, jumlah batang per meter juring, jumlah ruas, panjang batang, bobot batang, nilai brix nira batang bagian atas, tengah dan bawah, rendemen serta hasil hablur. Hasil penelitian menunjukkan bahwa genotipe berpengaruh terhadap keragaan hasil tebu dan komponen hasilnya. Genotipe MLG 1308 mempunyai produksi hablur tertinggi diantara genotipe lain, 21% lebih tinggi dibandingkan varietas pembanding PS 864 dan 156% dibandingkan dengan Kenthung. Dengan demikian genotipe MLG 1308 adalah genotipe harapan untuk pengembangan tebu di lahan kering. Kata kunci: Saccharum officinarum, uji daya hasil, lahan kering, genotipe unggul

Abstract. Rudarmono, Ardiarini NR, Waluyo B, Ashari S. 2022. Interspecific and Intraspecific cross-compatibility of Durio kutejensis and hybrid Durio zibethinus x kutejensis. Biodiversitas 23: 1837-1843. Lai (Durio kutejensis) and Mandong (Durio zibethinus x kutejensis) fruits that have advantages and high consumer preference values. Fruit productivity and development of Lai and Mandong plant varieties are still not optimal. The aim of this study was to analyze the level of incompatibility of interspecific and intraspecific crosses between Lai (D. kutejensis) and Mandong (D. zibethinus x kutejensis hybrid) plants. Artificial crosses were made utilizing flower samples from Mahakam, Kutai, and Batuah types of Lai plants, as well as Mandong varieties of Mandong, employing a scheme of 20 crossings that included a combination of these varieties (12 treatments), as well as each variety from the same flower and tree (8 treatments). The intensity level and incompatibility classification were determined according to Wang's (1963) method, which was based on the number of fruits formed from artificial crosses, and the pollen incompatibility intensity level (IIL) was determined according to the ratio of flowers that produced fruit from the cross to the total number of flowers crossed. The results showed that overall crosses of the same flower (selfing) from three varieties of Lai and one variety of Mandong were incompatible. Lai Mahakam x Lai Batuah crosses yielded 14.28 % harvested fruit, Lai Mahakam x Lai Mahakam crosses yielded 18.75 % harvested fruit, Lai Kutai x Lai Kutai crossings yielded 14.81 % harvested fruit, while a cross of Durian Mandong x Lai Batuah yielded 16.67 % harvested fruit. It shows partially compatible. The complete compatibility value showed the number of harvested fruit ranged from 23.44 to 46.77%, with the most significant being obtained from a Lai Mahakam x Durian Mandong cross. The Mahakam, Kutai, Batuah, and Mandong varieties are compatible with all pollen sources.

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