Kelas Benih Kentang (Solanum tuberosum L.) Berdasarkan Pertumbuhan, Produksi, dan Mutu Produk

<p>Sistem perbenihan kentang yang ada saat ini terdiri atas lima kelas benih, yaitu G0, G1, G2, G3, dan G4. Kelas benih G0 sampai G3 merupakan benih sumber, sedangkan kelas benih G4 merupakan benih sebar. Banyak penangkar, petani maupun stakeholder lainnya berpendapat bahwa proses produksi benih kentang dari kelas G0 sampai G3 cukup lama sehingga penyediaan benih untuk kentang konsumsi (G4) tidak dapat dilakukan secara cepat. Kegiatan penelitian bertujuan untuk mengetahui tingkat produktivitas kentang masing-masing kelas benih G0 sampai G4 agar dapat direkomendasikan sebagai kelas benih untuk kentang konsumsi. Penelitian dilakukan di Kebun Percobaan Margahayu Balitsa Lembang dari bulan September sampai November 2012 menggunakan rancangan acak kelompok dengan enam perlakuan, yaitu kelas benih (G0, G1, G2, G3, G4, dan kontrol) dan empat ulangan. Parameter yang diamati meliputi pertumbuhan tanaman, produksi, dan mutu produk. Hasil penelitian menunjukkan bahwa kentang yang berasal dari kelas benih G3 menghasilkan produksi dan kelas umbi A dan B yang tertinggi sehingga cocok untuk benih sebar. Untuk peningkatan produksi ternyata kelas benih yang lebih tinggi (G0 dan G1) memiliki peningkatan produksi dan menghasilkan umbi kelas C dan D yang lebih tinggi daripada kelas benih di bawahnya sehingga cocok dikategorikan sebagai benih sumber.</p><p>Potato seed systems that exist today consists of five seeds classes, namely G0, G1, G2, G3, and G4. G0 to G3 seed is the source seed, while classes G4 seed was extension seed. Many breeders, farmers and other stakeholders argue that the process of seed production from G0 to G3 class was too long so that the supply of potatoes seeds for consumption (G4) could not be carried out faster. Research was conducted to determine the level of productivity of each class of potato seed G0 to G4 to be recommended as a seed class for potato consumption. The reseach was conducted at Margahayu Experimental Garden of Indonesian Vegetable Research Institute Lembang from September–November 2012 in randomized block design with six treatments : seed class (G0, G1, G2, G3, G4, and control) with four replications. The parameters observed were plant growth, production, and product quality. Hence, it can be concluded that potatoes derived from G3 class was quite suitable for extension seeds. The higher the seed class (G0 and G1) the higher the increasing rate and it produced higher number of C and D tuber grade.</p>

Management of common scab of potato using planting and harvest dates

The influences of planting and harvest dates on yields and grade-out due to tuber damage by common scab (Streptomyces spp.) were evaluated over three cropping seasons using two cultivars of potato (Solanum tuberosum) grown on land heavily infested with pathogenic Streptomyces species. Early planting and delaying the harvest enhanced yields in both cultivars, but also increased tuber grade-out due to excessive levels of scab. Delaying the harvest reduced marketable yields more than did early planting. The longer harvest was delayed after top-kill, the greater was the grade out due to scab. Increased losses to scab exceeded any increase in tuber yields obtained by delaying harvest. This study demonstrates that common scab of potato may be managed by minimizing the period the crop is in the ground, but that this method of disease management is achieved at the expense of yields. Early planting coupled with timely harvesting after kill-down of the tops appears to be an effective compromise between the objectives of maximizing yields while avoiding excessive grade-out due to common scab. Key words: Potato scab, Streptomyces scabies, Solanum tuberosum, agronomy

589 Calcium Application at Preemergence and during Bulking May Improve Tuber Quality and Grade

An increase in calcium concentration of potato tuber tissue has been shown to reduce soft rot severity and the incidence of internal physiological defects. Higher tuber calcium also seems to increase sprout vigor and maintain apical dominance by reducing subapical necrosis and sprout tip death. Preemergent applications of calcium at a rate of 0 and 26.5 kg·ha–1 from ammonium nitrate (PreAmNit), ammonium nitrate plus calcium nitrate (PreCaN), or calcium chloride plus calcium nitrate plus urea (PreCUC). A group of post-emergent split calcium nitrate plus calcium chloride plus urea (PostCUC) applications beginning with hilling and proceeding at 3, 6, and 8 weeks after hilling were also made at a rate of 56 kg·ha–1 calcium at each application time. From visual ratings of stand quality taken 64 days after hilling, we found plants receiving a preemergent application of nutrients or PostCUC had higher stand ratings than paired control plots. Internal tuber quality ratings revealed less internal brown spot in the PostCUC application in 168–364-g tubers. Yield of 112–168-g tubers was greatest from plants treated with PreCaN or PreCUC followed by PostCUC. PreAmNit plots had higher culls than the PreCUC plots. The non-split ammonium nitrate control (all nitrogen by hilling) produced a higher number of B-sized tubers than the PostCUC treatment. Also the PreAmNit+PostCUC had more B-sized tubers than PreCaN+PostCUC. In general the PostCUC treatment produced fewer small tubers and more large tubers than other treatments. These results suggest application of a small amount of calcium prior to emergence but after the sprouts have begun to develop improves seed performance. Furthermore these data show that supplemental calcium application during the season may improve tuber grade.