Influence Of Sowing Dates Research Articles

Sowing date influence on the soybean tolerance to defoliation at the beginning of pod formation

Late sowings anticipate flowering and decrease the soybean vegetative plasticity. These changes may limit the ability of plants to tolerate leaf area losses. The objective of this research was to evaluate the sowing date effect on soybean tolerance to defoliation at the beginning of pod formation. The experiment was set in Lages (Santa Catarina State, Brazil) during the 2016/2017 growing season. Two sowing dates were tested: November 2, 2016 (preferential) and December 15, 2016 (late). Five levels of defoliation (0%, 17%, 33%, 50% and 67%) of cultivar NA 5909 RG were imposed at the R3 growth stage. Grain yield showed a quadratic response to defoliation, ranging from 4,313 to 6,478 kg ha-1 in the preferential sowing date and from 3,374 to 4,443 kg ha-1 in the late sowing date. The plants tolerated up to 45.6% of defoliation in early sowing and 55.8% in late sowing, without yield losses, in comparison to the control. The highest level of defoliation reduced grain yield by 26.9% and 13.4% in early and late sowings, respectively, compared to the control. The delay of sowing date did not increase the sensitivity of cultivar NA 5909 RG to defoliation at the beginning of pod formation.

INFLUENCE OF SOWING DATES AND SEED PLACEMENT DEPTH ON FIELD GERMINATION THAT YIELD CHICORY ROOT CROPS

INFLUENCE OF SOWING DATES AND SEED PLACEMENT DEPTH ON FIELD GERMINATION THAT YIELD CHICORY ROOT CROPS

Influence of different sowing dates of winter pea genotypes on winter hardiness and productivity as either winter catch crop or seed legume

The main purpose of this study was to examine the influence of three sowing dates (mid of September, beginning of October, mid of October) on the winter hardiness and productivity of six different genotypes of winter peas (Pisum sativum L.). The two field trials were conducted with winter peas in either pure stands as winter catch crop for biomass yield (three seasons) or mixed stands with rye as a seed legume (two seasons; seeding rate 20 and 225germinableseedsm−2, respectively) on the experimental farm of the University of Kassel, Germany.The main findings suggest that only those genotypes can be recommended for cultivation that have adequate winter hardiness. Results support the conclusion that winter peas have sufficient winter hardiness for cultivation in transitional climatic conditions when they display a rosette growth with small leaves and short internodes at the onset of winter and possess quantitative photoperiodic sensitivity. For these genotypes, no impact of the sowing date on the extent of winter hardiness could be determined.In the experiment winter pea pure stands, the highest biomass yield (assessed at the onset of flowering) was determined for the earliest sowings. In the experiment with winter pea/rye mixture, the influence of sowing date on seed yield of the frost-resistant peas was negligible.

Sowing date influence on winter oilseed rape overwintering in Estonia

In 2001–2005 an overwintering investigation of winter oilseed rape (Brassica napus L.) was carried out at the Institute of Agricultural and Environmental Sciences of the Estonian University of Life Sciences. In our trial we used two winter oilseed rape varieties: ‘Wotan’ and ‘Express’. The sowing was performed at four different times, with weekly intervals: 8, 15, 22 and 29 August. The soil type was Stagnic Luvisol by WRB classification; the texture was sandy loam with a humus layer of 20–30 cm. Our research indicated that successful wintering of winter oilseed rape depends directly on sowing date. From the data obtained it may be seen that differences between sowing dates and overwintering were statistically significant. Overwintering depends on numbers of growing-degree-days (GDD) in the autumn vegetative period. Three years’ data showed that in the autumn period plants need 416 GDD for developing a strong root system and to prepare for wintering.