Silva Grobelnik Mlakar

Yield performance and agronomic efficiency in oil pumpkins (Cucurbita pepo L. group Pepo) depending on production systems and varieties

Abstract In 2013 and 2014, a long-term trial (which was established in 2007) was conducted at the University Agricultural Centre in Pivola near Hoče. It included different production systems (conventional, integrated, organic, biodynamic), carried out in a field trial with oil pumpkins. The aim of the research was to analyse the effects of different production systems, varieties (hybrid and population variety) and years of production, on formation of oil pumpkin yields. The agricultural practice has been carried out in accordance with the applicable legislations and standards for the individual production system. When sowing, before fertilizing with nitrogen in early June and after the harvest, the amount of soil mineral nitrogen was monitored. We evaluated the number and weight of harvestable, unripe and decayed fruits, and yield of oil seed pumpkins and calculated the agronomic efficiency of the applied nutrients. The results showed that the year of production, the production system and the variety have a significant effect on some fruit characteristics and the yield of oil pumpkin seeds. The content of soil mineral nitrogen in May and September was significantly influenced by the production system and the year. In June, only the production system had a significant effect. The hybrid significantly increased the yields of oil pumpkin seeds in all production systems, even in the year that was less suitable for production. The agronomic efficiency of the applied nutrients in the biodynamic and organic production system is higher or equal than in the conventional production system, similarly, agronomic efficiency is higher in the hybrid compared to the oldest population variety efficiently. A comparable oil pumpkin yield can be expected in biodynamic and organic production, when proper nutrition and well carried out cultivation practices are combined with a new variety, when compared to less sustainable production systems, which often cause damage to the environment.

Growth performance, productivity and diseases susceptibility of barley varieties in Slovenia within the Cobra project's site comparison

Abstract Different plant genotypes react differently in different climates. A field experiment was carried out to estimate the growth performance, productivity and diseases susceptibility of spring barley varieties in the Slovenian climate. We received some varieties, mainly of Nordic origin, from the Technical University of Denmark, a COBRA project partner, which were previously tested in estimated future climate in RERAF phytotron. Varieties of the highest grain yield (3,993 kg ha-1 in ‘Evergreen’ to 5,146 kg ha-1 in ‘Sebastian’) were rather shorter (58.7 cm to 67.1 cm) and mostly had the highest specific grain weight (54.3 to 58.6 kg 100 L-1) and 1000-kernel weight (30.2 to 37.1 g). They developed 1,561 to 2,532 tillers m-2 and 515 to 840 ears m-2 and reached a heading stage between 13th and 25th of May. The tested varieties seem rather insusceptible to most common diseases, but susceptible to cereal leaf beetle attacks.

Sweet maize growth and yield response to organic and mineral fertilizers, N rates and soil water regimes.

Abstract Sweet maize is an underutilized vegetable in European temperate areas, and its consumption is increasing. For better understanding of cultivation practices, this pot experiment aimed to determine the effects of different water regimes and nitrogen (N) rates calculated from N target values. N rates of 0 (control), 0.6 and 2 g N pot-1 were applied as organic by-products pumpkin cake and pig manure digestate, and mineral fertilizers CAN 27 and ENTEC®26. Treatments of water supply were based on measured soil matric potentials of 2.8 pF (drought stress), 2.6 pF (optimal water) and 2.4 pF (overwatered). In comparison to mineral fertilizers, pumpkin cake proved to be equal in effectiveness in plant height (155.8 cm), cob (85.8 g), green (124.9 g) and leaf mass per plant (44.2 g), or even better in root (72.3 g) and broom mass per plant (3.0 g). Yield parameters, cob mass (70.1 g), its length (6.3 cm) and diameter (2.0 cm), as well as the residual mineral N (59 mg N kg-1) significantly increased at the highest N rate. Significantly lower values of the evaluated morphological parameters and photosynthetic rates (at brooming and harvesting) were associated with drought stress. The matric tension of 2.6 pF was established as an appropriate water regime for sweet maize growth.