Reduced water consumption of dormant-seeded sugar beet in a semiarid climate
Dormant seeding refers to sowing spring crop species in fall. In the spring, seedlings start growing and the crop is established before spring sowing is normally completed. A dormant-seeded crop can establish quickly in spring and may escape from early season drought. A study was conducted to compare performances of dormant seeding with early and late spring seeding of sugar beet. Field experiments were carried out in the Khorasn province (NE of Iran) in 2002 and 2003 by growing a bolting resistant variety (BR1). The experiment consisted of a randomized complete block design with four replications. Dormant seeding was subjected to six irrigation treatments in addition to an early and late spring seeding. The first irrigation was applied 0, 10, 20, 30, 40 and 50 days after 60% soil moisture depletion. After harvest, root yield, sugar concentration, white sugar yield, and non-sugar components of the root samples were measured and analyzed. The results of the dormant seeding showed that root yield of sugar beet decreased with increasing delay of irrigation at the early stages of plant growth. High white sugar yield was obtained at dormant seeding without irrigation delay compared to the early seeding. No significant differences were observed for white sugar yield until three and five water withholdings in 2002 and 2003, respectively. In the second year of the experiment (2003), a relatively cold winter induced about 4.5% bolters and reduced plant population with 33% compared to the early and late spring sowing treatments. In general, white sugar yield produced in response to specific irrigation amounts for dormant-seeded treatments was higher compared to early and late seeding. However, dormant seeding cannot yet be recommended as a comprehensive agricultural practice for sugar beet and, therefore, further investigations are required to improve the quality of the beet by both agronomic techniques and new improved varieties.
Effect of seeding date on canola seed quality and seed vigour
Seedling vigour is a key critical component to produce well-established canola (Brassica napus) seedlings under less than ideal conditions in western Canada. Our objective was to determine if seed lots from late October (fall) or early spring (April) seeding dates improve seed vigour relative to mid-May (May) seeding dates. We compared seed size, seed maturity, germination percentage, and seedling emergence under controlled-environment conditions from six seed lots obtained from fall-sown (1997, 1998), April-sown (1998, 1999) and May-sown canola (1998, 1999) cv. Quest. On average, 80% of fall-derived seed for both years was larger than 1.7 mm compared to only 32% for May-derived canola seed. April-derived seed was intermediate. Fall and April derived seed were considered 40% mature compared to 16% for May-derived seed. In germination tests at 8°C, May derived seed germinated and emerged slower with a lower total germination percentage compared to falland April-derived seed lots. Priming reduced difference...
Sugar Beet Response to Water Stress in Sandy Soils
ABSTRACT LEAF xylem pressure data suggest brief reductions to about -14 to - 15 bars may be tolerable pro-vided average pressure over 10-20 day intervals is above — 12 bars. Seasonal average pressures of -15 and -21 bars were found to reduce yields to 0.6 and 0.1 that of a nonstress treatment, respectively. Water management criteria based upon allowable levels of leaf xylem pressure are suggested.