Judul: Effect of Maturation Stages and Seed Position within a Fruit of Sugar apple (Annona squamosa Linn.) on Seedling Performance by Optimizing the Use of Plant Growth Promoting Rhizobacteria (PGPR
Abstrak: Benih srikaya yang bermutu sangat diperlukan untuk mendukung pengembangan bibit tanaman srikaya. Penelitian ini bertujuan menentukan tingkat kemasakan dan posisi benih dalam buah yang tepat guna mendapatkan benih bermutu dan mendapatkan perlakuan terbaik untuk meningkatkan performa bibit melalui penggunaan rizobakteri dan CaCO3. Percobaan pertama menggunakan rancangan acak lengkap (RAL) dua faktor dengan faktor pertama adalah warna kulit buah dan faktor kedua adalah posisi benih dalam buah. Percobaan kedua menggunakan RAL dengan rizobakteri, CaCO3, dan kombinasi keduanya sebagai faktor tunggal. Waktu hitungan pertama pengamatan daya berkecambah pada 36 hari setelah tanam (HST) dan hitungan akhir pada 56 HST. Kualitas benih terbaik diperoleh dari warna kulit buah kuning berdasarkan bobot kering benih, daya berkecambah, indeks vigor, bobot kering kecambah normal, dan kecepatan tumbuh benih. Vigor tumbuh benih tertinggi diperoleh dari buah dengan warna kulit kuning dari bagian ujung dan pangkal buah. Perlakuan CaCO3mempengaruhi pemanjangan akar, lebar daun, diameter batang, dan panjang daun. Aplikasi CaCO3 memberikan pengaruh terbaik terhadap pertumbuhan bibit diikuti dengan perlakuan Pseudomonas + Actimomycetes + CaCO3.
Keyword: Annona squamosa, batang bawah, hitungan akhir, indeks vigor,  rizobakteri, Annona squamosa, batang bawah, hitungan akhir, indeks vigor, rizobakteri

Judul: Induksi Pembungaan dan Perbaikan Mutu Buah Srikaya Jumbo (Annona squamosa L.)
Abstrak: Sugar apple (Annona squamosa-Annonaceae) is one of favorite local fruits. The main constraint in increasing fruit production is low flower production and dichogamy in which male and female reproductive organ did not mature at the same time. The objectives of this research were to increase flower production by pruning and to improve fruit quality by pollination. The research was conducted in Pakem, Sleman, North Yogyakarta in February until July 2013. The research consisted of two experiments, both were arranged in randomized complete block design with one factor. The factor for the first experiment was pruning i.e. total pruning, partial pruning, and unprunned as control. The second experiment was started with observation on flowering phenology from appearance of flower buds to anthesis, and continued on the receptive period of stigma. Following the observation pollination in which three types of pollination was employed, i.e. controlled pollination, natural pollination, and modified natural pollination. The result of the first experiment showed that flowering increased by total pruning up 83.3% and by partial pruning up to 41.8% compared to unprunned trees. The fruit yield from totally prunned trees was 5%, partially prunned was 3.9%, and unprunned was 2.2% of the flower bud appearance. Observation on flowering phenology showed that development of flower bud appearence until anthesis took 25-34 days. The receptivity of the stigma occurred twice during 05.00 am - 14.00 pm and 17.00 pm - 02.00 am. Controlled pollination resulted in 90 % fruit set as compared to 70 % fruit set in natural and modified natural pollination. Controlled pollination produced more symetrical fruit, ranged 136.8-287.8 g, natural pollination ranged 150.0-367.8 g. Modified natural pollination produced the smallest fruit ranged 82.0-235.2 g.
Keyword: sugar apple, stigma receptivity, pollination, pruning, dichogamy

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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