The development of isolated, defined wheat microspores undergoing in vitro embryogenesis has been followed by cell tracking. Isolated wheat (Triticum aestivum L.). microspores were immobilized in Sea Plaque agarose supported by a polypropylene mesh at a low cell density and cultured in a hormone-free, maltose-containing medium in the presence of ovaries serving as a conditioning factor. Embryogenesis was followed in microspores isolated from immature anthers of freshly cut tillers or from heat- and starvation-treated, excised anthers. Three types of microspore were identified on the basis of their cytological features at the start of culture. Type- microspores had a big central vacuole and a nucleus close to the microspore wall, usually opposite to the germ pore. This type was identical to the late microspore stage in anthers developing in vivo. Microspores with a fragmented vacuole and a peripheral cytoplasmic pocket containing the nucleus were defined as type 2. In type-3 microspores the nucleus was positioned in a cytoplasmic pocket in the centre of the microspore. Tracking revealed that, irrespective of origin, type-1 microspores first developed into type 2 and then into type-3 microspores. After a few more days, type-3 microspores absorbed their vacuoles and differentiated into cytoplasm-rich and starch-accumulating cells, which then divided to form multicellular structures. Apparently the three types of microspore represent stages in a continuous process and not, as previously assumed, distinct classes of responding and non-responding microspores. The first cell division of the embryogenic microspores was always symmetric. Cell tracking also revealed that the original microspore wall opened opposite to a region in the multicellular microspore which consisted of cells containing starch grains while the remaining cells were starch grain-free. The starch-containing cells were located close to the germ pore of the microspore. In more advanced embryos the broken microspore wall was detected at the root pole of the embryo.

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ABSTRAKPenelitian ini dilakukan untuk mengetahui karakteristik morfologi, produktivitas dan kualitas rumput gajah kultivar Taiwan, King dan Mott yang dipanen pada umur 8 dan 13 setelah tanam. Pengaruh kultivar dan umur panen disusun dalam Rancangan Tersarang (3x2). Peubah yang diamati terdiri atas karakteristik morfologi, produksi bahan kering dan kualitas hijauan. Hasil penelitian menunjukkan bahwa karakteristik morfologi, rasio daun batang, kadar serat, kandungan protein kasar dan kecernaan in vitro bahan kering rumput gajah kultivar Taiwan dan King tidak berbeda, namun keduanya memiliki karakteristik morfologi, kandungan serat lebih tinggi (P<0,05) dibandingkan dengan kultivar Mott, sebaliknya rasio daun batang, kandungan protein kasar dan kecernaan in vitro bahan kering kultivar Mott lebih tinggi (P<0,05) dibandingkan dengan kultivar Taiwan dan King. Secara umum, terjadi peningkatan tinggi tanaman dan kadar serat pada umur 13 minggu, sedangkan kandungan protein kasar dan kecernaan in vitro bahan kering menurun. Disimpulkan bahwa produksi bahan kering tertinggi terdapat pada kultivar Taiwan dan King, sedangkan kualitas tertinggi terdapat pada kultivar Mott. Produksi bahan kering tertinggi pada umur 13 minggu, sedangkan kualitas tertinggi pada umur 8 minggu setelah tanam untuk semua kultivar diuji.Kata kunci : kualitas, kultivar, produksi, rumput gajah ABSTRACTThe research was conducted to determine the morphological characteristics, productivity and quality of Napier grass cultivars Taiwan, King and Mott harvested at 8 and 13 after planting. Effect of cultivar and harvest arranged in a nested design (3x2). The variables were observed consisting of morphological characteristics, dry matter production and forage quality. The results showed that the morphological characteristics, leaf stem ratio, fiber content, crude protein content and in vitro dry matter digestibility of Napier grass Taiwan and King cultivar were not different, but both morphological characteristics, fiber content was higher (P <0.05) compared to Mott cultivar, whereas leaf stem ratio, crude protein content and in vitro dry matter digestibility Mott cultivar was higher (P <0.05) compared to Taiwan and King cultivars. In general, an increase in plant height and fiber content at the age of 13 weeks, whereas crude protein content and in vitro dry matter digestibility decreased. It was concluded that the highest dry matter production found in Taiwan and the King cultivars, whereas highest quality found in Mott cultivar. Dry matter production was highest harvested at 13 weeks, whereas the highest quality harvested at 8 weeks after planting for all cultivars tested. .