Judul: Determination of Harvest Time for Water Spinach Seeds (Ipomoea reptans Poir.) based on The Stage of Maturation
Abstrak: Panen yang dilakukan serempak menghasilkan benih kangkung darat dengan tingkat kemasakan beragam. Benih belum masak bermutu rendah, sementara benih lewat masak cenderung mengalami seed coat-imposed dormancy. Oleh karena itu waktu panen perlu ditetapkan untuk mendapatkan proporsi benih mencapai masak fisiologi terbesar. Penelitian ini bertujuan mempelajari pola pembungaan tanaman kangkung dan menentukan umur panen serentak untuk mendapatkan proporsi benih masak fisiologi tertinggi. Penetapan waktu panen dilakukan dalam Rancangan Kelompok Lengkap Teracak (RKLT) satu faktor, yaitu waku panen yang terdiri atas 24, 26, 28, dan 30 hari setelah antesis (HSA). Hasil penelitian menunjukkan puncak pemunculan kuncup bunga terjadi pada 42-68 HST dan mulai mekar pada 51-60 HST. Bunga mekar satu hari, terjadi pada 10-11 setelah kuncup muncul dan buah masak sekitar 30 hari setelah bunga mekar. Fruit set berkisar 86±0,24% dan seed set berkisar 72±0,23%. Panen serentak menghasilkan benih dengan warna berbeda, yaitu coklat terang (belum masak), coklat gelap (masak) dan hitam (lewat masak). Daya berkecambah benih cokelat gelap dan hitam > 80%, sementara benih cokelat terang sekitar 66%. Benih masak fisiologi ditandai berwarna coklat gelap, dicapai pada 20-30 hari setelah bunga mekar. Panen pada 24 HSA dan 26 HSA menghasilkan proporsi benih coklat gelap tertinggi., Water spinach seeds are harvested at once; when the whole plant is removed from the field. Consequently, the seeds are of various maturity levels, including overripe seeds that tend to experience seed coat-imposed dormancy. This study aimed to study flowering patterns and to determine the suitable harvest time in order to obtain the highest proportion of physiologically matured seeds. The research was arranged in a randomized complete block design with one factor, time of harvest, i.e., 24, 26, 28, and 30 days after anthesis (DAA). The results showed that the peak of flower bud emergence occurred at 42-68 DAP and began to bloom at 51-60 DAP. The flowers only bloom one day, occurring 10-11 days after the buds appear and the fruit ripens about 30 DAA. Fruit set around 86±0,24% and seed set 72±0,23%. Harvesting the seeds at once resulted seeds with different colors, light brown (immature), dark brown (ripe) and black (ovveripe). The germination rate of dark brown and black seeds is >80%, while light brown seeds are around 66%. Physiologically mature seeds are marked with a dark brown color, reached 20-30 DAA. Harvesting at 24 DAA and 26 DAA produced the highest proportion of dark brown seeds.
Keyword: antesis, black seeds, dark brown seeds, flowering,light brown seed

Judul: Determination of Short Term Storage to Maintain Quality of Water Spinach Seeds (Ipomoea reptans Poir.)
Abstrak: Benih yang dipanen saat masak fisiologis akan memiliki mutu yang maksimal. Benih perlu disimpan pada kondisi yang optimum untuk mempertahankan mutunya. Penelitan ini bertujuan menetapkan kondisi simpan jangka pendek benih kangkung sehingga mutunya dapat dipertahankan. Rancangan yang digunakan adalah rancangan acak lengkap faktorial dua faktor dengan 4 ulangan. Faktor pertama adalah warna benih kangkung yaitu hitam, cokelat gelap, dan cokelat terang. Faktor kedua adalah ruang simpan yaitu ruang ber-AC (suhu 16 - 21 °C, RH 55 – 63%) dan ruang kamar (suhu 27,4 – 30,3 °C, RH 64 - 87%). Setiap ulangan terdiri atas 25 benih. Hasil penelitian menunjukkan bahwa benih kangkung darat berwarna hitam dan cokelat gelap telah mencapai masak fisiologis, sehingga viabilitas dan vigor lebih tinggi dibandingkan warna cokelat terang. Benih berwarna cokelat terang belum mencapai masak fisiologis, dan memiliki viabilitas yang rendah. Ruang ber-AC (suhu 16 - 21 °C, RH 55 – 63%) dan ruang kamar (suhu 27,4 – 30,3 °C, RH 64 - 87%) dapat digunakan untuk mempertahankan mutu benih kangkung darat yang dikemas dalam aluminium foil dengan kadar air awal 9% untuk penyimpanan jangka pendek (14 minggu)., The seed quality is highest when it reaches physiological maturity. In order to maintain the quality, the seed needs to be stored in an optimum condition. The study was aimed to determine the proper short term storage conditions for kangkong seeds for maintaining the quality. This study was arranged in a completely randomized design with two factors and repeated 4 times. The first factor was seed coat color i.e. black, dark brown, and light brown and the second factor was the storage condition i.e. air-conditioned room (temperature 16-21 °C, RH 55-63%) and ambient room (temperature 27,4 – 30,3 °C, RH 64 - 87%). Each replicates consisted of 25 seeds. The results showed that the black and dark brown colors of kangkong seeds has reached physiological maturity therefore had higher viability and vigor than that of the light brown seeds. The light brown seed is physiologically immature, and have low viability. For short term storage (14 weeks) air-conditioned room (temperature 16-21 °C, RH 55-63%) and ambient room (temperature 27,4 – 30,3 °C, RH 64 - 87%) were sufficient to maintain the quality of kangkong seeds packed in aluminium foil with 9% initial moisture content.
Keyword: seed coat color, storage condition, viability, vigo

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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