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The studies concerned the variability in nectar and pollen production in flowers of 75 double-low lines of white mustard (Sinapis alba L.) and a reference cultivar ‘Nakielska’. Also, rates of insect visitation to flowers in 19 lines were investigated. Significant genotypic differences were found in nectar amount, sugar concentration in nectar and total nectar sugar amount. The average nectar amount/10 flowers varied from 2.3 to 24.4 mg, with a mean 14.7 mg for ‘Nakielska’. Nectar concentration for most lines exceeded 20%. The majority (52%) of the lines tested produced more than 2 mg of sugars/10 flowers in nectar. The average amounts of pollen varied from 1.2 to 12.0 mg/10 flowers, with the mean 8.5 mg for ‘Nakielska’. No clear genotypic effect on the amount of pollen/10 flowers was demonstrated. The lines did not differed significantly in their attractiveness to flower visitors. The main foragers were honey bees (93% of all visiting insects). It is concluded that the double-low lines of S. alba are comparable to conventional cultivars in their potential for nectar flow but perform poorer as pollen producers. The studies concerned the variability in nectar and pollen production in flowers of 75 double-low lines of white mustard (Sinapis alba L.) and a reference cultivar ‘Nakielska’. Also, rates of insect visitation to flowers in 19 lines were investigated. Significant genotypic differences were found in nectar amount, sugar concentration in nectar and total nectar sugar amount. The average nectar amount/10 flowers varied from 2.3 to 24.4 mg, with a mean 14.7 mg for ‘Nakielska’. Nectar concentration for most lines exceeded 20%. The majority (52%) of the lines tested produced more than 2 mg of sugars/10 flowers in nectar. The average amounts of pollen varied from 1.2 to 12.0 mg/10 flowers, with the mean 8.5 mg for ‘Nakielska’. No clear genotypic effect on the amount of pollen/10 flowers was demonstrated. The lines did not differed significantly in their attractiveness to flower visitors. The main foragers were honey bees (93% of all visiting insects). It is concluded that the double-low lines of S. alba are comparable to conventional cultivars in their potential for nectar flow but perform poorer as pollen producers.
The present study was conducted in the years 2007- 2008, after 6-year-long experiments in the cultivation of spring barley in a crop rotation system and in monoculture. The other experimental factor was the spring barley protection method. Intensive protection involved comprehensive treatment of barley (in-crop harrowing, seed dressing, application of herbicides, fungicides, a retardant and an insecticide). Extensive protection consisted only in in-crop harrowing, without the application of crop protection agents, except for seed dressing. The above mentioned factors formed the background for the study on the cultivation of white mustard and oats, as phytosanitary species, in successive years. In the test plants, no mineral fertilization and crop protection were applied. Such agricultural method enabled an objective assessment of the consequent effect of monoculture, crop rotation and crop treatments. A hypothesis was made that the cultivation of the phytosanitary plants in the stand after 6-year-long barley monoculture would allow obtaining the level of yields and weed infestation similar to those of the crop rotation treatments. It was also assumed that the cultivation of white mustard and oats would eliminate differences in plant productivity caused by the negative influence of extensive protection. It was proved that the cultivation of the phytosanitary plants eliminated the negative influence of monoculture on the level of their yields and weed infestation. However, the test plants did not compensate negative consequences of extensive protection. In spite of this, white mustard and oats effectively competed with weeds, and the number and weight of weeds in a crop canopy did not cause a dramatic decline in yields. In the test plant canopy, the following short-lived weeds were predominant: Chenopodium album, Galinsoga parviflora, Echinochloa crus-galli. The absence of herbicide application resulted in the compensation of perennial species: Elymus repens and Cirsium arvense.
Stigmas isolated from flower buds of ‘Nakielska’ variety of Sinapis alba were used to develop a micropropagation method suitable for breeding of new cultivars. The origin of adventitious bud regeneration was studied on MS medium, under stimulation by bezylaminopurine (BAP) in combination with 2,4-D - naphtoxy acetic acid (2,4-D). Histological analysis showed the structure of Sinapis stigma (composed from four types of tissue: papillae, transmitting tissue, parenchyma and vascular bundles) and revealed that numerous meristematic centers developed from parenchyma cells in close vicinity of vascular bundles. Buds very quickly appeared on the surface of initial explants and later formed multiplantlets that were easily rooted in the soil.
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