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Siniša Srečec, Vesna Zechner-Krpan, Sanja Marag, Igor Špoljarić, Ivka Kvaternjak and Gordan Mršić

Morphogenesis, volume and number of hop (Humulus lupulus L.) glandular trichomes, and their influence on alpha-acid accumulation in fresh bracts of hop cones

The ESEM investigations revealed the morphogenesis of peltate glandular trichomes, which was divided into five phases. In phase one, new peltate glandular trichomes were initiated; in phase two, they were differentiated; in phase three trichomes grew vigorously; in phase four they were determined; in the fifth and final phase they came to maturity. Volume of glandular trichome during the different phases of morphogenesis varied from 0.25 × 10-2 mm3 in phase 1, to 1.95 × 10-2 mm3 in phase 5. More glandular trichomes are placed on the base of the adaxial side of bracts (average 7 mm-2) than on the base of abaxial side (average 5.8 mm-2). In this research, positive Spearman's rank order correlations were found between the average number of glandular trichomes and content of α-acids as well as between the average volume of glandular trichomes and content of α-acids.

Open access

Ivka Kvaternjak, Ivica Kisić, Marta Birkás, Andrija Špoljar and Dejan Marenčić

Abstract

At the experiment station of the Krizevci College of Agriculture, yield and yield components of maize (Zea mays L.) and soybean (Glycine max) grown in rotation under five different methods of tillage were investigated. The aim of this study was to determine the effect of different tillage methods on yield and yield components of maize and soybean. The results and the determined number of plants per hectare of maize and soybean show that more favorable conditions for germination are in variants where ploughing performed in the autumn (variants C, D and E). During a four-year study, the minimum number of plants per hectare of maize and soybean was found in variant A. The dry season in panicle stage of maize in 2006 has lowered yields compared to 2008, and the drought in 2007 during the seed-filling period reduced the yield and the 1000 kernel weight of soybean compared with 2009 in all variants of tillage methods. The highest grain yield of maize was recorded in variant B. During 2006, with the unfavorable weather conditions, the lowest grain yield of maize was recorded in variant E with intensive tillage treatment. The highest yield of soybean was recorded in variant E, but there were no statistically significant differences compared to variants with the reduction of additional tillage interventions (variant B, C and D). With respect to maize grain and soybean seed yield, variant A was the lowest. Considering the achieved yields of maize grain, there is a possibility of reducing additional tillage interventions, whilst for achieving higher yield of soybean seed intensive tillage is recommended.