Judul: Pengaruh Perlakuan Pendahuluan dan Berat Benih terhadap Perkecambahan Benih Kayu Afrika (Maesopsis eminii Engl.)
Abstrak: INTRODUCTION. Kayu Afrika (Maesopsis eminii Engl.) is categorized as fast growing and exotic species in Indonesia. The use of Kayu Afrika were for light construction, packaging, boxes, and even for ply wood raw materials. In terms of its potensial, Kayu Afrika has good prospect to be developed for plantation forest. For the planting of this species, there is a need for high quality seeds with high vigor and germination capacity. Seeds of Kayu Afrika have strong dormancy feature due to their hard and thick seed coat. The breaking of the such dormancy needs a certain treatment to the seed. Research concerning the effect of pretreatment on germination of Kayu Afrika seeds has ever been conducted, but it had not been fully able to break the dormancy of the seeds. Seed size has some correlation with vigor. The relatively heavy seeds are preferable due to its general relation with germination quality. MATERIALS AND METHOD. This research consisted of two experiments designed as Completely Randomized Experimental Design. The first experiment comprised the factor of seed pretreatment, consisting of 12 treatments, namely soaking in coconut water for 1,2 and 3 hours; water for 24, 48 and 72 hours; H2SO4 1% for 10, 20 and 30 minutes; and KNO3 0.2% for 15, 30 and 45 minutes. The second experiment comprised the factor of seed weight, consisting of 3 treatments, namely the use of heavy seeds (≥ 1.50 gram), moderate seeds (1.25-1.50 gram) and light seeds (≤1.25 gram). Variables observed for each experiment were germination capacity, growth speed and germination value. For learning the effect of treatments on the observed variables, Analysis of Variance was performed. If the treatment showed significant effect, further Duncan test were performed to test the differences between means. The obtained data were analyzed with the aid of SPSS program version 12.0. RESULTS AND DISCUSSION. Seed moisture content of Kayu Afrika during this research ranged between 15.75%-16.95%. Weight of 1000 seeds ranged between 1378.7-1436.3 gram, and number of seeds/kg ranged between 696-725 seeds/kg. Research results showed that seed pretreatments of soaking in coconut water for 1,2 and 3 hours; water for 24, 48 and 72 hours; H2SO4 1% for 10, 20 and 30 minutes; and KNO3 0.2% for 15, 30 and 45 minutes had significant effect on germination capacity, and growth speed of Kayu Afrika seeds, howefer, they did not have significant effect on germination value of Kayu Afrika seeds. Similarly, seed weight did not have significant effect on germination capacity, growth speed and germination value of Kayu Afrika seeds. CONCLUSION. All pretreatments of soaking in coconut water, water, H2SO4 1% and KNO3 0,2% were able to increase seed germination capacity of Kayu Afrika from less than 50% to more than 65%. Statistically, soaking in coconut water (1, 2 and 3 hours), water (24 and 72 hours), H2SO4 1% (10, 20 and 30 minutes) and KNO3 0,2% (15, 30 and 45 minutes) did not differ significantly in increasing seed germination capacity and seed growth speed of Kayu Afrika. Howefer, all those treatments differed significantly from treatment of soaking in water for 48 hours.
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Judul: Daya Kecambah dan Pertumbuhan Kayu Afrika (Maesopsis eminii Engl.) di Lahan Pasca Tambang Batubara Pada Metode Direct Seeding
Abstrak: Lahan pasca tambang mempunyai kondisi yang kurang mendukung untuk dilakukannya penanaman maupun revegetasi. Revegetasi ditunjukan untuk memperbaiki kondisi lingkungan yang dapat memberikan manfaat ekologis, ekonomis, dan sosial secara berkelanjutan. Metode direct seeding merupakan salah satu metode yang dapat digunakan dalam mendukung keberhasilan kegiatan revegetasi dengan biaya yang lebih murah. Tujuan penelitian ini adalah untuk mengetahui kedalaman penanaman yang sesuai dalam penanaman benih kayu afrika pada lahan pasca tambang batubara dan kemampuan tumbuh dari tanaman kayu afrika pada lahan dengan pH rendah di areal pasca tambang batubara, serta mengetahui kadar kapur yang sesuai dalam mendukung pertumbuhan benih kayu afrika di lahan pasca tambang batubara. Jenis benih yang digunakan adalah kayu afrika (Maesopsis eminii Engl.) ditanam langsung di lapangan dengan jarak tanam 2 x 4 meter dan ditanam 2 benih per lubangnya menggunakan rancangan acak lengkap (RAL) dengan dua faktor. Parameter yang diamati antara lain daya berkecambah, persen hidup, diameter tanaman, tinggi tanaman dan jumlah daun. Hasil penelitian menunjukkan bahwa kadar kapur berpengaruh nyata terhadap daya kecambah, tinggi, diameter, dan jumlah daun tanaman. Pemberian kadar kapur 0.5 kg memberikan pengaruh terbaik pada parameter daya berkecambah, tinggi tanaman, diameter tanaman, dan jumlah daun tanaman. Perlakuan kedalaman penanaman 2 cm berpengaruh nyata terhadap tinggi tanaman dengan nilai rata-rata pertumbuhan sebesar 6.15 cm dalam satu bulan pengamatan.
Keyword: Direct seeding, kayu afrika, lahan pasca tambang, revegetasi

Judul: Invers Drazin dari Matriks Toeplitz Singular
Abstrak: Matriks Toeplitz adalah matriks yang setiap unsur pada diagonal utama bernilai sama dan setiap unsur pada subdiagonal yang bersesuaian dengan diagonal utama juga bernilai sama. Matriks singular adalah matriks yang tidak bisa ditentukan inversnya. Akan tetapi, dapat diupayakan untuk ditentukan inversnya menggunakan invers matriks yang diperumum. Invers Drazin merupakan salah satu jenis invers matriks yang diperumum. Pada karya ilmiah ini ditentukan invers Drazin dari matriks Toeplitz singular dengan menggunakan metode Leverrier Faddeev. Kemudian, ditentukan invers Drazin dari matriks Toeplitz singular yang direpresentasikan sebagai penjumlahan segitiga bawah dan segitiga atas matriks Toeplitz berdasar pada teorema Gohberg dan Semencul., Toeplitz matrix is a matrix in with element on the main diagonal has the same value and on the subdiagonal corresponding to the main diagonal also has the same value. Singular matrix is a matrix that has no inverse. However, it can be attempted to determine the inverse using a generalized inverse matrix. Inverse Drazin is a type of generalized matrix inverse. This paper discussed the inverse Drazin for a singular Toeplitz matrix using the Leverrier Faddeev method. Then, the Drazin inverse of the singular Toeplitz matrix which is represented as a sum of products of lower and upper triangular Toeplitz matrix based on Gohberg and Semencul theorem.
Keyword: inverse Drazine, singular Toeplitz matrix