Agnieszka Klimek-Kopyra

Modification of the tree root electrical capacitance method under laboratory conditions

For many years, scientists have been searching for nondestructive methods for the measurement of plant root system parameters. The measurement of electrical capacitance (EC) across the root has been proposed as one such nondestructive method. This article presents a study on the determination of relationships between EC measurement and the shape and size of the electrodes immersed in medium that are used for measurement. Measurement of EC and the parameters characterizing root systems of 1-year-old seedlings of the common beech Fagus sylvatica L. was conducted under laboratory conditions. The measurements of EC were performed between seedling root systems and two different electrodes in the form of a cylinder or a rectangular plate. Statistically significant correlations were found between the capacitance and root system parameters in both the variants; however, the correlations were higher in the case of the flat rectangular plate. Correlation coefficient (r) between EC and total root length was  0.688 for cylindrical electrode and  0.802 for rectangular plate, for total root area 0.641 and 0.818, and for dry weight of root system 0.502 and 0.747. The best-fitted linear regression relationships between the EC and the measured parameters were characterized by low determination coefficients in variants with cylindrical electrodes, and higher with flat rectangular plate electrodes. The results indicated that a two-dielectric media concept is a better model than Daltons model when attempting to interpret the behavior of root and soil capacitance. The different electrodes probably allow root capacitance measurements to be interpreted from different aspects. However, this hypothesis requires further verification.

Morphological and molecular identification and PCR amplification to determine the toxigenic potential of Fusarium spp. isolated from maize ears in southern Poland

The average amount of precipitation in spring and summer 2010 and 2011 coupled with relatively high temperatures caused massive Fusarium spp. infection of maize and yield losses in southern Poland. In order to examine the cause of this disease outbreak, Fusarium spp. were isolated and fungal strains were identified based on morphological characters and species-specific PCR assays. A total of 200 maize samples were processed, resulting in the obtention of 71 strains, which belonged to five Fusarium species, F. poae being the predominant one (74.56%). Other isolates were identified as F. graminearum, F. oxysporum, F. verticillioides and F. proliferatum. PCR-based detection of mycotoxin-synthesis-pathway genes was also used to determine the potential of the analyzed strains to produce trichothecenes (DON and NIV) and fumonisins (FUM). Only 14 isolates revealed the potential to produce DON (11 strains) and FUM (3 strains). HPLC analyses of grain samples revealed the presence of DON only – other mycotoxins were not detected. Moreover, 57.1% of potentially mycotoxin-producing isolates indicated the toxicity in a biological test.

Vertical distribution of dry mass in cereals straw and its loss during harvesting

Abstract The study aimed at evaluating the distribution of mass in the straw of cereal species and also at assessing the straw yield and its losses resulting from the amount of the stubble left in the field. It was found empirically that the wheat culms are composed of five internodes, and in barley, triticale and oats of six. The highest straw mass per 1 cm was found in the second internode in both forms of wheat and winter triticale, whereas barley and oats gathered the highest weight in the first internode. In the southern part of Silesia species and forms of cereals differed in the straw yield, which can be arranged as follows, from the highest: winter wheat > spring wheat, winter triticale, winter barley, and oats > spring barley. Due to the specific distribution of dry matter in each of internodes of both wheat forms - winter and spring, they loose less stubble mass (22 and 24%, respectively), comparing to other cereals, especially spring barley, which loose 31% yield of straw in the stubble of 15 cm height.

A comparison of the chemical composition of the seeds of linseed and pea cultivars grown in pure stands or mixtures

ABSTRACT A three-year field experiment was conducted to compare the chemical composition of the seeds of two linseed-pea mixtures, that is the cv. ‘Flanders’ with the cv. ‘Ramrod’ and cv. ‘Barbara’ with cv. ‘Phönix’. The results indicate that the chemical composition of the seeds of the linseed cultivars was not significantly affected by the sowing method, indicating that the species traits of linseed are constant. The mixed sowing increased the content of threonine and proline in the protein of the Flanders cultivar seeds and slightly increased the protein content of the seeds of both linseed cultivars in the mixtures with pea.

Dependence of pea root mass distribution on weather conditions under varying levels of phosphorus application

Abstract The aim of the study was to describe the distribution of pea root mass in the soil, over a three-year period, under varying weather conditions and at different levels of phosphorus application, by means of evaluating and comparing parameters of a mathematical model characterising cumulative root mass distribution. A two-factor experiment was conducted in Prusy, near Krakow: the first factor was the level of phosphorus application (0-70-140 kg P2O5 ha−1) and the second was the cultivars (six cultivars were tested). Experimental data produced using the model indicated that the root distribution was strongly differentiated by water availability in the years of the study. This appeared in some cases to be a more important factor than phosphorus application rates. The estimated soil depth at which 50% of the root mass was accumulated differed significantly for the dry and the wet year. In the wet year, only very high phosphorus application rates contributed to an increase in root mass distribution. The estimation of root mass distribution from the presented data can be used to improve phosphorus application depending on the amount of precipitation.

Accumulation of biomass and bioenergy in culms of cereals as a factor of straw cutting height

Abstract Cereal straw is an important biomass source in Europe. This work assessed: 1) the morphological and energetic characteristics of culms of spring and winter cereals, 2) the energy deposited in the different aboveground parts of cereals, 3) losses of energy due to different cutting heights. The straw of winter and spring cereals was collected from arable fields during the seasons 2009/10 and 2010/11 in southern Poland. Detailed biometric measurements of culms and internodes were performed. The losses of straw biomass and energy were assessed during simulation of cutting the culm at different heights, up to 50 cm. Longer and heavier culms were developed by winter wheat and triticale and oat. Cutting of straw up to 10 cm did not lead to significant losses in straw yield. The total amount of energy in the culms was as follows: triticale > winter wheat > oat > spring wheat > winter barley > spring barley. Cutting the culms above 20 cm led to significant differences in terms of biomass energy between cereal species. The smallest losses of energy were recorded for spring and winter barley. Oat and barley accumulated the highest energy in grains.

Ordinal regression model for pea seed mass

Summary The development of seeds at various positions in the pod is asynchronous. Thus, the differences of seed dry mass production because of environmental conditions may depend on the cultivar type, type of inoculants and interrelations between seeds per pod, pods per plant or seeds per plant. Presently, a mathematical description of pea seed categorisation is missing. The aim of the study was the assessment of two groups of variables (quantitative and qualitative) for pea seed weight categorisation by ordinal regression model. Year, cultivar and inoculant constituted the first group (qualitative variables), whilst seeds per pod, the pods per plant and seeds per plant (quantitative variables) were entered as covariates in the ordinal regression model. According to the ordinal regression model variables, seeds per pod, pods per plant, seeds per plant, year and cultivar are meaningful predictors of the seed mass categories. However, the variable inoculant is marginally significant.

Agronomic performance of naked oat (Avena nuda L.) and faba bean intercropping

The most common cereals for faba bean (Vicia faba L.) used in intercrops is conventional oat (Avena sativa L.) An alternative to oat may be naked oat (Avena nuda L.), whose oil content and quality is double. Here, intercropping of naked oat with two different faba bean cultivars (determinate-high tannin and indeterminate-low tannin) was compared with sole crops of each species in 2006-2008. The treatments were: sole naked oat at 500 kernels m2, indeterminate sole faba bean at 50 seeds m2, determinate sole faba bean at 70 seeds m2, and an additive series of 25%, 50%, and 75% of faba bean seeding rate mixed with the naked oat seeding rate. Our results demonstrated that intercropping increased the Land Equivalent Ratio by +3% to +9% over sole cropping. Raising the faba bean seeding rate in a mixture from 25% to 75% reduced oat grain yield from 630 (determinate cultivar) to 760 kg ha-1 (indeterminate cultivar) but increased faba bean grain yield from 760 kg ha-1. Higher yield and leaf area index (LAI) and photosynthetically active radiation (PAR) values show that the indeterminate cultivar of faba bean is more suitable in mixture with naked oat. The high value of competition index (CR > 1) indicates domination and aggressiveness of faba bean towards naked oat. Regardless of cultivar type, mixture of faba bean with naked oat is less productive than pure sowing.