Photosynthetic and storage limitation to yield in Sorghum bicolor (E57)

English. To study the relationship between sink and source in sorghum E57, an experiment was done by altering assimilate supply and storage capacity of the grains. This experiment was done at Redland Bar Research Station, Australia, during January-March 1989. In this experiment assimilate supply was controlled by increasing or reducing the amount of solar radiation absorbed by plant. Increasing the amount of solar radiation was done by thinning up to 50 percent from the initial population. To reduce the amount of solar radiation absorbed, shading treatments were applied at two periods, three weeks before anthesis up to anthesis and the other was from anthesis to maturity. The capacity of plant to store assimilate in the grains simulated by removing spikelets at anthesis, 25 percent and 50 percent respectively. These five treatments were then arranged in a completely randomized block design with three replications. The results showed that decreasing the number of grains by spikelet removal increase grain size. By increasing the percentage of spikelet removal more assimilate was tranlocated to other sink component such as stem. Reducing solar radiation up to 50 percent which was simulated by shading from anthesis to maturity resulted in less assimilate produced by plant and accordingly reduced yield and total dry matter. In these shading treatments more assimilate was transferred to stem than to grain. Improvement in solar radiation absorbed by plant through thinning increased yield component of sorghum E57. From this experiment, it can be concluded that yield of sorghum E57 was limited by source than by sink

unknown. Untuk meneliti kaitan antara "sink" dan "source" pada tanaman sorgum E57, sebuah penelitian dilakukan dengan meragamkan produksi asimilat dan kapasitas penyimpanan asimilat di dalam biji. Penelitian dilaksanakan di Kebun Percobaan Redland Bay, Australia pada bulan Januari - Maret 1989. Dalam penelitian ini produksi asimilat dikendalikan dengan menambah atau mengurangi jumlah radiasi yang diterima. Penambahan jumlah radiasi dibuat dengan melakukan penjarangan tanaman hingga 50 persen dari populasi awal, sedangkan untuk mengurangi jumlah radiasi yang diterima oleh tanaman dilakukan pemberian naungan pada dua periode pengamatan, yaitu tiga minggu sebelum sampai fase antesis dan dari antesis sampai panen. Kapasitas tanaman untuk menyimpan asimilat di dalam biji disimulasi dengan mengurangi jumlah calon biji pada fase anthesis, masing-masing 25 persen dan 50 persen. Kelima perlakuan tersebut kemudian disusun dalam rancangan acak kelompok dengan tiga ulangan. Hasil penelitian menunjukkan bahwa pengambilan " spikelet " pada fase antesis meningkatkan ukuran biji tersisa pada fase pematangan. Dengan bertambahnya persentase dari "spikelet" yang diambil, menyebabkan banyak asimilat dialokasikan kepada komponen "sink" yang lain, misalnya batang