Fresh, senesced, and decaying pine needles from Pinus halepensis were evaluated for their allelopathic potential on Festuca arundinacea, Cynodon dactylon and the biosensor plants Avena sativa and Lemna minor through in vivo and in vitro studies. The in vivo study was performed in growth chambers, using 6, 12, and 18 g of pine needle tissue mixed with screened perlite as a substrate. The effects of the different pine needle types were evaluated by determining the total root length, total root surface, root dry weight, total shoot length, total shoot surface, and shoot dry weight. The in vitro study was performed in Petri dishes where seeds from each species were subjected to an increasing concentration of pine needle extract. The extracts were obtained from pine needle ground tissue that was diluted with water and either shacked at room temperature or placed in water bath at 40 °C for 24 h. The evaluation of the allelopathic potential was performed with the determination of radicle length. The allelopathic potential of the pine needle tissues was confirmed with bioassays using oat (A. sativa) and duckweed (L. minor). The results strongly suggested the allelopathic potential of the pine needle tissue, being more pronounced in the fresh, moderate in the senesced, and low in the decaying pine needles. The allelopathic substances were species-specific, and the inhibition resistance of the species tested followed the order F. arundinacea > C. dactylon > A. sativa. The inhibition of the L. minor suggested that the water soluble phytotoxic compounds were inhibitors of Photosystem II.

Studies were conducted in four regions of central Greece (Larisa, Karditsa, Livadia, Thiva), to evaluate the productivity and fibre properties (fibre strength and fibre length) of the five most commonly grown cotton cultivars in these regions. The experiments lasted for 6 years (1995)(1996)(1997)(1998)(1999)(2000). All the characteristics tested were strongly influenced by the factors ÔyearÕ, ÔcultivarÕ and ÔregionÕ. Significant cultivar · region, year · cultivar, region · year and cultivar · region · year interactions occurred for all the characteristics studied. The cultivar Alegria had the highest seed-cotton and lint yield, while Aria had the lowest ones. Both cultivars gave the highest mean lint percentage but the lowest mean boll weight (MBW). Alegria had the lowest fibre strength, while Aria had the highest. The Acala-type cultivars, Acala SJ2 and Zeta 2, had intermediate seedcotton and lint yield, while Vered 171 had high seed-cotton and satisfactory lint yield. The three cultivars mentioned above had the highest MBW and very good fibre strength. Positive correlation was observed between fibre strength and length. In spite of the fact that mean fibre length was statistically the same in all cultivars, it was influenced by the factor ÔyearÕ, as a result of different weather conditions. The year 1996 was the most unfavourable one for seedcotton yield and MBW, because it was characterized by lower than average air temperatures and rather dry conditions for all study sites. The factor ÔregionÕ, a combination of different climatic conditions and cultural practices, influenced significantly all the parameters studied.

Field experiments were conducted to determine the e}ects of tillage "ploughing followed by one rotary hoeing "CT#\ rotary hoeing "MT# and no!tillage "NT## and type of fertilization "NP 043:64 kg ha −0 \ digested farmyard manure 29 t ha −0 # on growth "biomass and roots#\ N! accumulation and nodulation of vetch plants "Vicia sativa cv[ Alexander# at di}erent stages[ The highest dry matter yields and root weight were determined for the NT and the lowest for the CT systems[ The NT system promoted nodulation of vetch plants to a higher degree than the MT and CT systems[ At the time just before harvesting\ the N!accumulation in the above ground plants\ was 43[2 for CT\ 65[6 for MT\ and 098[9 kg ha −0 for NT\ and the corresponding values at roots were 62[2\ 001[9 and 062[2 kg ha −0 [ Growth and nodulation of vetch plants was in general much better on farmyard manure plots than it was with the NP fertilization[ The closest cor! relation coe.cients between dry matter of biomass and roots on the one hand\ and number of nodules and per! centage N in roots on the other\ were found with NT[ The highest correlation between nodulation and percentage N in roots "r 9[80 # was observed at the 017!days!old vetch plants[ The highest correlation between the number of nodules and percentage N in biomass "r 9[71 # was found at the beginning of the plants|~owering period[ \ \ indicate signi_cance at P 9[94\ 9[90 and 9[990 respectively[

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Seed production and performance of lucerne is characterized by fluctuating yields with often poor seed quality, and is dependent on environmental conditions, genetic characteristics and agronomic techniques applied during seed set, development, maturation and storage. A field experiment was carried out in two successive growing seasons at Kopais (southern Greece) to evaluate the effects of drought stress imposed by three irrigation treatments, and temperature during flowering and seed filling on lucerne seed yield and quality. Plant water status, expressed in terms of the water potential index (WPI), growth in leaf area and dry weight, seed yield and yield components, flowering and seed quality parameters were measured throughout the growing seasons. The adopted irrigation schemes produced a clear differentiation among treatments concerning their plant water status. Seed yield and leaf growth showed close positive correlations with WPI. An irrigation effect was also detected for the number of pods/plant, but not for the average weight of seeds/pod. Less negative values of WPI, and, especially, higher temperatures during flowering were also positively associated with a longer duration of flowering, as well as with higher total numbers of inflorescences. A very good description of the time course of seed germination was performed by fitting the Richards’ function to the real data. By examining the germination parameters derived from this function it was found that final germination and germination rate were improved, while germination duration was shortened with more negative values of WPI. The effects of growing season and seeding period were occasionally equally or more important than irrigation effects. These results are also discussed in terms of their practical implications for seed producing lucerne crops.

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