Abstract. Two different field trials with triticale were carried out in a field of the Department of Field Crop Husbandry of the Estonian Agricultural University, situated near Tartu, in 2000/2001–2002/2003. In the first trial, the winter triticale cultivars ‘Modus’ and ‘Tewo’ were used to investigate the influence of different N fertilisation regimes on triticale yield formation and yield quality. Seven N fertiliser treatments in four replications in the first year and 11 fertiliser treatments in three replications in the second and third year were tested, by varying total nitrogen dosages and time of application. Nitrogen was applied as NH4NO3 at different plant development stages (EC30, EC47). In the second trial, 10 winter triticale cultivars were investigated (‘Modus’, ‘Tewo’, ‘Lasko’, ‘Dagro’, ‘Ulrika’, ‘Lamberto’, ‘Vision’, ‘Fidelio’, ‘Lupus’, and ‘Prego’) to select out cultivars of earlier maturing and higher tolerance to pre-harvest sprouting. Winter triticale parents – the winter rye ‘Vambo’ and the winter wheat ‘Kosack’ were used as the control.  
The yield level and quality of winter triticale grains were most of all affected by weather conditions and then by cultivars and N application regimes. Nitrogen fertiliser application at the plant development stage EC47 decreased significantly the height of stems (r = -0.459***), which is the principal prerequisite for preventing lodging, and increased significantly grain protein content (1.69 and 1.8% as the average of three years in ‘Modus’ and ‘Tewo’ grains, respectively). Unlike spikes of wheat, all of these winter triticale cultivars started to germinate before general physiological maturity. The longer was the period from anthesis to general physiological maturity, the higher was the percentage of germination during the period (r = 0.727*). The higher was the moisture content in seeds of triticale 26 days after the EC65 (length of the period wheat reached physiological maturity), the higher was the germination percentage in spikes (r = 0.733*). Triticale cultivars with higher 1,000 kernel weight values reached physiological maturity later. An average germination before harvest time correlated positively with test weight (r = 0.608*). 

Key words: triticale, N application regime, protein content, physiological maturity, pre-harvest sprouting

Abstract. The influence of organic farming on weed seed bank under two different crop rotations: with and without manure, was investigated in an organic farm of Kazliskiai over the period of 1997–2002. Proven by qualitative index, organic farming increases the diversity of weed species. Seeds of 10 weed species were found in one experimental field at the beginning of a transition period and, after 6-year organic farming, the diversity of weeds increased almost up to 16 species. In all years of the investigation, seeds of Chenopodium album, Fallopia convolvulus and Stellaria media were found in 0–25 cm soil layer. In the sixth year of organic farming there were found 26.3, 70.0 and 91.2% less seeds of the mentioned species, respectively, compared with the transition period. At the beginning of organic farming, the amount of weed seeds in the soil was 28.0% bigger in fields of crop rotation with manure, compared to crop rotation without manure but, in the sixth year of organic farming, the difference disappeared. All weeds were distributed into 3 biological and 4 ecophysiological groups and 3 types of dispersal. Most of seeds found in 0–25 cm soil layers were therophytes. Most of them germinate in summer, spread by water (barochory), because Chenopodium album dominates. Both in fields of the 1st and 2nd crop rotation and in all experimental years, the quantitative and qualitative distribution of weeds into biological, ecophysiological groups and types of dispersal was even, with the exception of ecophysiological groups in crop rotation with manure. 

Key words: organic farming, weed seed bank, manure 

 Abstract. In spring 2002, nine clonal rootstocks: the German ‘Gisela 5’, the Russian ‘LC-52’, ‘OVP-2’, ‘OVP-3’, ‘VC-13’, ‘VSL-2’, ‘V-2-180’, ‘V-2-230’ , ‘V-5-172’ and Prunus mahaleb L. seedlings (control), were planted at a nursery of Polli Horticultural Institute and in late July the sweet cherry cultivar ‘Kristiina’ and three selections ‘Karmel’, ‘Polli 10/8’ and ‘Polli 6/2’ were budded on them. The highest bud take percentages were observed on V-2-230, OVP-2, and V-5-172. Incompatibility between ‘Karmel’ and several rootstocks was noted. The growth of one-year-old plants at the nursery was most vigorous on P. mahaleb seedlings, OVP-2 and OVP-3 and the weakest on VC-13. The trunk diameters of the clonal rootstocks were significantly smaller than those of the control rootstocks. 

Key words: sweet cherry, clonal rootstocks, bud take, growth vigour, compatibility

 Abstract. In 1998–2000, the effect of local Estonian lime materials (oil shale ash, cement clinker dust, limestone meal, dolomite meal and their mixtures) used for neutralising acid bog peat on the contents of available plant nutrients (K, Ca, Mg) and on Ca:Mg, Ca:K, K:Mg ratios in peat substrate was investigated. The substrate were made on NPK and NP backgrounds. Lime materials, the Ca:Mg ratio of which varied between 3.4–16.7:1, were applied at a rate of 8 kg (in some variants 6 and 10 kg) per m³ peat. The substrate were analysed 2 and 4 weeks after their production.
The pH_KCl of growth substrate became stable almost within 2 weeks. Dolomite meals neutralised peat acidity approximately by 0.5–0.7 units less than the same rate of dusty lime fertilisers. The higher the Mg-content in lime material, the weaker its neutralising effect. While using a 1:1 mixture of limestone and dolomite meal, the content of available Mg in the substrate was sufficient for plant growth and it was possible to leave out the application of Mg-fertiliser to the substrate. The Ca:Mg ratio in growth substrate was considerably broader than in lime materials and depended significantly on the type of lime. The content of available Ca in substrate increased relatively more than that of available Mg. Under the effect of dusty lime fertilisers the Ca:Mg ratio had shifted in favour of Ca by 1.2–1.4 times, in the case of carbonate rock meals the preponderance of Ca had increased by 3.6–3.9 times. The best variants for neutralising peat acidity in the given research were as following: 1:1 mixture of limestone meal and dolomite meal and 1:1 mixture of clinker dust and dolomite meal. In these cases the contents of Ca, Mg and K and their mutual ratios in the substrate corresponded in the best way to the limit values needed for the optimum growth of greenhouse vegetables.

Key words: peat substrate, limestone, dolomite, oil shale ash, cement clinker dust, content and ratios of available Ca, Mg, and K 

 Abstract. The trials were performed in the years 1998–2000 in Saku (59°18’N, 24º39’E) in greenhouse conditions. The aim was to establish how lime materials used for the neutralisation of bog peat acidity (oil shale ash, clinker dust, limestone meal, dolomite meal and their mixtures), which changed significantly the contents of available Ca, K and Mg in the peat substrata, affect the mineral composition of vegetable leaves (lettuce, cucumber, tomato, paprika) and the mutual relationships between elements (K, Ca, Mg, P). In the case of all vegetables, a strong Ca and Mg antagonism occurred. The Mg content of plants was very sensitive to the Ca:Mg ratio in the lime material used for peat neutralisation. In the case of limestone meal, the tomato plants contained Mg 0.18–0.24% and cucumber plants 0.36–0.40%; in the case of dolomite meal, 0.66–0.71% and 0.78–0.90, respectively. The Ca and K contents of vegetables were somewhat less affected by the difference of lime materials than the Mg content. Abundant Mg in lime material increased P content in plants, a synergism between Mg and P occurred.  
Lettuce grown on substrata neutralised with mixtures of limestone and dolomite meal contained less nitrates than that grown on substrata with clinker dust and oil shale ash. Too high K content in the substrate neutralised with clinker dust had a negative effect on the carotene content of lettuce.

Key words: peat substrate, limestone, dolomite, oil shale ash, cement clinker dust, tomato, cucumber, lettuce, pepper, mineral content in leaves, nitrate, carotene

 Abstract. Aimed at elaboration of a soil fertility module for the potato production model POMOD, the determination of growth functions was carried out for the late potato variety ‘Anti’ at different fertilisation levels. These functions characterise the distribution of growth between plant organs and redistribution of the biomass of vegetative organs at their late growth stage. Results of the field experiments in 2002–2003 revealed that fertilisation decreased the maximum of root growth function and shifted the maximum of leaf growth function forward. The bigger amount of fertiliser slows down the decrease of leaf and stem growth functions and the increase of tuber growth function. Moreover, it leads to a break in the tuber growth function occurring with secondary maximums in leaf and stem growth functions. Variability of growth functions induced by fertilisation is dominant during the second half of growing period. At an early growing stage, variations between years exceed variability between fertilisation plots. 

Key words: growth functions, fertilisation, potato, crop modelling

 Abstract. The aim of the research was to study floral nectar characteristics of different cultivars of arctic bramble in Estonian conditions. The amount of nectar and sugar concentration of the arctic bramble cultivar ‘Pima’ (from Finland) and a clone from Estonian wild nature (‘Kaansoo’) were studied in 1999. The cultivars differed in their flowering intensity and nectar producing ability. The abundance of flowers of the local clone (‘Kaansoo’) was significantly higher compared to the cultivar ‘Pima’, but the cultivar ‘Pima’ produced much more nectar than the Estonian clone. The concentration of sugar in nectar was significantly higher in flowers of the local clone. In comparison with other plants, the amount of nectar in arctic bramble flowers was not high, consequently, pollinators prefer plants richer in nectar. Therefore it is recommendable to cut the grass around a plantation and between the rows of arctic bramble during flowering and bring additional pollinators, e.g. honeybee hives, to the plantation.  

Key words: arctic bramble, Estonian clone, flower, sugar concentration

 Abstract. This research (A long-term field experiment from 1982 to 1997) was conducted at the experimental station of the Department of Field Crop Husbandry of the Estonian Agricultural University. The soil of the experimental site is moderately moist slightly podzolised sandy clay.
Insofar as field crop husbandry is concerned the soil should contain optimal amounts of available nutrients. If the level of available nutrients in the soil is low the plants will suffer and the yield will be low. A rise in soil available nutrient content leads to increased yield of crops, but only up to a certain level (optimal content). Thereafter, a further rise in soil nutrient content fails to effect any significant increase in the harvest.
The soils of the Eerika trial plot have optimal nutrient content and little need for fertilisation. After two crop rotations significant changes in nutrient content and location were observed in the ploughed layer. Compared to the nutrient content determined at the start of the trial period (1982), the greatest changes occurred in the soils under a crop rotation involving cereals, potato and a mixture of red clover and timothy, in which the supply of available phosphorus decreased by 19 mg kg^-1 and that of potassium by 121 mg kg^-1 on average after two rotations. Compared to the cereal rotation and the rotation containing 50% of cereals and 50% of potato the available phosphorus content dropped by 12–33% and the potassium content by 41–46% in the upper 25-cm soil layer.  

Key words: Phosphorus, potassium, nitrogen, ploughing, loosening, plant nutrient balance

 Abstract. Soils in Estonia are characterised by washing out, i.e. leaching, of calcium carbonates and magnesium carbonates. Calcium losses from the arable layer may amount 150–500 (600) kg ha-1 a year, resulting in excessive concentration of free hydrogen ions in the soil solution, and therefore these soils require liming. Relatively high doses of lime fertilisers have to be used in order to eliminate harmful acidity of the soils. Clinker dust, oil shale ash and milled limestone are the materials widely used as lime fertilisers at present. Soils in Estonia are often poor in both potassium and magnesium, and that is why clinker dust, which is relatively rich in potassium, has been a particularly valued lime fertiliser. Magnesium deficiency is being alleviated by adding dolomite meal to milled limestone. However, a non-uniform mixing of these lime fertilisers does not ensure their sufficiently homogeneous consistence. Large doses of lime fertilisers, which are not uniformly mixed, have a variable effect on the contents and ratios of calcium, potassium and magnesium in the soil. The trials showed that, as a result of an incorrect use of lime fertilisers, both calcium-to-magnesium and potassium-to-magnesium ratios in the soil may change to the detriment of plants, leading to lower yields.

Key words: acid soils, lime fertilisers, calcium, magnesium, potassium; yield; red clover (Trifolium pratense L.), Italian ryegrass (Lolium multiflorum Lam. ssp. italicum (A. Br.) Volkart)

 Abstract. Field trials, to investigate the effect of microfertilisers on the oil content of seeds of the oilseed rape cultivar ‘Mascot’, were carried out at the Department of Field Crop Husbandry in 2002-2003. We used in our trial 7 different microfertilisers. Prior to the sowing, the field was sprayed with herbicide EK Trifluralin and mineral fertiliser OptiCropNPK 21-08-12+S+Mg+B+Ca, calculating 120 kg N ha-1. Plants were treated with microfertilisers on 26 June. Analyses of test results revealed that different microelements influenced the oil content of rape seeds. The positive effect was noted in variants where rape plants were treated with micronutrients and micronutrients mixtures. The highest oil content, 43.4% of seeds dry matter, had Molybdenum-treated rape.

Key words: spring oilseed rape, micronutrients, fertiliser, oil content

 Abstract. Influence of red clover (Trifolium pratense L.), sown lucerne (Medicago sativa L.), vetch and oat mixture (Vicia sativa L., Avena sativa L.) and green material of these legume crops used as green manure on the build up of biological N variation of soil properties and productivity of winter wheat (Triticum aestivum L.) was investigated on Endocalcari-Endohypogleyic Cambisol (CMg-n-w-can), according to the texture – clay loam on silty clay. Experiments were carried out at the Joniskelis Research Station of the Lithuanian Institute of Agriculture over the period 1996–2000. It was revealed that lucerne and clover left the highest content of plant residues in the soil (13.7 t ha-1 and 9.2 t ha-1 of dry matter, respectively) which was 2.7 and 1.8 times more as compared to annual vetch and oat mixture. These perennial plants also determined accumulation of the highest content of biological N in roots and residues. According to N content applied with green manure, only lucerne aftermath was comparable to farmyard manure. Lucerne determined accumulation of the highest contents of total nitrogen (0.138%), humus (2.18%) and available phosphorus and potassium (130 and 279 mg kg-1 of soil, respectively) in the soil. Analysis of humus composition showed that its content in clay loam soil was rather stable, however, a slightly higher content of mobile humic acids was found after lucerne as a preceding crop when green manure or farmyard manure had been applied. When winter wheat was grown after lucerne as a preceding crop, the highest grain yield (on average 5.58 t ha-1) was obtained, which was 18.5 and 28.3% higher than that after clover or vetch and oat mixture. Protein content in winter wheat grain was to a greater extent determined by legume crops rather than organic manure. 

Key words: clay loam, legume crops, green manure, humus, winter wheat

Key words:  campaniform sensilla, cooling, impulse activity, single-sensillum recording, thermoreceptor