Fieldexperiment with spring rape (Brassica napus var. oleifera f. annua) cultivars Star andLisonne was conductedin the years 1995–1999 at the vicinity of Olsztyn, Poland. The herbicides trifluralin (Triflurotox 250 EC), alachlor + trifluralin (Alatrif 380 EC), metazachlor (Butisan 400 SC) andclopyralid(Lontrel 300) were appliedin spring rape according to recommendations (Zalecenia 1993). The aim of this study was to estimate the effect of the herbicides on glucosinolates content in spring rape seeds. The obtainedresults revealedsignificant effect of meteorological conditions on glucosinolates content. The Star cv. was characterizedby higher level of these compounds in comparison with Lisonne cv. The adequate values were 15.96 μmol g^-1 of d.m. and 12.32 μmol g^-1 of d.m., respectively. It is evident on the base of the statistical analyses of the obtained results that herbicides modified glucosinolates content in seeds of both cultivars. The level of these compounds was increased as the effect of Triflurotox 250 EC use (data obtainedfrom three years investigations) and Alatrif 380 EC (four years) while Butisan 400 SC activity was unfavourable (four years).

The influence of glucosinolates isolated from oilseed rape seeds on the growth of pathogenic fungi infecting oilseed rape was studied. The activity of those compounds against 3 fungal species was tested in vitro. It was stated that glucosinolates present in the medium did not totally inhibit the growth of the fungi, but considerably confined the area of colonies of 2 out of 3 fungal species studied.

The influence of oilseed rape glucosinolates on the grown in vitro pathogenic fungi was studied. Two pathogenic to oilseed rape fungi species: Fusarium roseum and Rhizoctonia so/ani were taken into consideration. It was observed that glucosinolates added to the medium limited the growth of both tested fungi to some extent, especially when higher concentrations of glucosinolates was supplied.

Allelopathy is a complex phenomenon which depends on allelochemical concentrations. So, two pot experiments were carried out to investigate the allelopathic effect of alcoholic fresh shoot extract of Eruca sativa (foliar spray) and E. sativa shoot powder (mixed with soil) on Pisum sativum plants and two associated weeds, Phalaris minor and Beta vulgaris. The experiments were conducted in the greenhouse of the National Research Centre, Giza, Egypt during two successive winter seasons (2016–2017 and 2017–2018). Ten treatments were applied in this study. Four treatments were applied before sowing, that E. sativa shoot powder was mixed with the soil at rates of 15, 30, 45 and 60 g ⋅ pot–1. The other four treatments of E. sativa alcoholic fresh shoot extract were sprayed twice on both plants and weeds at 5, 10, 15 and 20% (w/v) concentrations. Additionally, two untreated treatments, healthy (P. sativum only) and unweeded (untreated infested P. sativum plants with weeds) were applied for comparison. The results indicated that both alcoholic extracts and powder reduced growth of both weeds. Moreover, there was a direct relationship between concentration and weed reduction. Eruca sativa alcoholic extracts increased yield parameters of P. sativum plants. The maximum yield attributes were recorded by spraying of E. sativa alcoholic extract at 20%. On the other hand, it was clearly noticed that the high powder rates affected negatively P. sativum yield parameters. But the lowest powder rate (15 g ⋅ pot–1) stimulated P. sativum yield parameters as compared to unweeded treatment. Chemical analysis of E. sativa shoot powder ensured that the abundant amount of glucosinolates (9.6 μmol ⋅ g–1) and phenolic compounds (46.5 mg ⋅ g–1) may be responsible for its allelopathic effect. In conclusion, spraying of alcoholic fresh shoot extract of E. sativa at 20% (w/v) and mixing E. sativa shoot powder at 15 g · pot–1can be applied as natural bioherbicides for controlling weeds.

The influence of saponins isolated from alfalfa (Medicago sativa L.) leaves and glucosinolates isolated from mustard (Sinapis alba L.) seeds on the fertility of Colorado potato beetles (Leptinotarsa decemlineata Say) reared on potato leaves treated with these substances was tested. It was observed that both compounds restrained the process of egg laying however, the action of saponins was stronger.