Borbála Hoffmann

Physiological and morphological responses to water stress in Aegilops biuncialis and Triticum aestivum genotypes with differing tolerance to drought

The physiological and morphological responses to water stress induced by polyethylene glycol (PEG) or by withholding water were investigated in Aegilops biuncialis Vis. genotypes differing in the annual rainfall of their habitat (1050, 550 and 225 mm year-1) and in Triticum aestivum L. wheat genotypes differing in drought tolerance. A decrease in the osmotic pressure of the nutrient solution from -0.027 to -1.8 MPa resulted in significant water loss, a low degree of stomatal closure and a decrease in the intercellular CO2 concentration (Ci) in Aegilops genotypes originating from dry habitats, while in wheat genotypes high osmotic stress increased stomatal closure, resulting in a low level of water loss and high Ci. Nevertheless, under saturating light at normal atmospheric CO2 levels, the rate of CO2 assimilation was higher for the Aegilops accessions, under high osmotic stress, than for the wheat genotypes. Moreover, in the wheat genotypes CO2 assimilation exhibited less or no O2 sensitivity. These physiological responses were manifested in changes in the growth rate and biomass production, since Aegilops (Ae550, Ae225) genotypes retained a higher growth rate (especially in the roots), biomass production and yield formation after drought stress than wheat. These results indicate that Aegilops genotypes, originating from a dry habitat have better drought tolerance than wheat, making them good candidates for improving the drought tolerance of wheat through intergeneric crossing.

Adaptation of wheat ( Triticum aestivum L) genotypes and related species to water deficiency

Wheat production is limited primarily by water deficiency. The challenge of our days is to increase production with less water by promoting biological basis of drought tolerance and higher water use efficiency (WUE).Eight genotypes were examined to make comparison of their response to drought. The plants were grown in pots filled with 8.5 kg soil. The drought stress was started at the mid-flowering stage (Zadoks’ scale: 65) and continued till maturity by adding only 50% of the water given to the control pots. Morphological and physiological characteristics known to be related to drought tolerance were examined.Duration of grain filling was shortened by 3 days in the mean of genotypes, the number of productive tillers were reduced by about 20% in case of the newly bred cultivars and 4–11% for extensive genotypes because of water deficiency. The highest root dry weight increment was measured in case of Emese (71%) and Pantlika (54%), while Cap.Des. increased it’s root weight only by 24%. Yield reduction was...

Grain yield and baking quality of wheat as affected by cropyear and plant nutrition

Hungarian agriculture is traditionally connected with the growing of winter wheat, which emerges from his suitable climatic characteristics. Despite of the general favourable meteorological situation, individual crop years can cause very different climatic conditions and also the territory of our land consists of more and less favourable wheat growing sites. Among climatic impacts especially weather conditions before harvesting influence baking quality (Tandcs et al. 2005). Heat stress can damage flour quality as well (Bencze et al. 2004). Effects of less favourable climatic and site conditions can be reduced by proper agronomy and growing excellent genotypes (Szentpeteri et al. 2004a, 2004b). Long-term field experiments have a very important role for assessment of agronomic impacts, because their history is well known and documented.

Improvement of the agronomic traits of a wheat–barley centric fusion by introgressing the 3HS.3BL translocation into a modern wheat cultivar

The 3HS.3BL spontaneous Robertsonian translocation obtained from the progenies of wheat-barley (Chinese Spring × Betzes) hybrids backcrossed with wheat line Mv9kr1 was transferred into the modern Martonvásár wheat cultivar Mv Bodri. The translocation was identified with molecular cytogenetic methods. The inheritance of the translocation was traced using genomic in situ hybridization. Fluorescence in situ hybridization using barley subtelomeric (HvT01) and centromere-specific [(AGGGAG)4] repetitive DNA probes confirmed that the complete barley chromosome arm was involved in the Robertsonian translocation. The wheat-specific repetitive DNA probes identified the presence of the whole wheat genome, except the short arm of the 3B chromosome. Genotypes homozygous for the centric fusion were selected, after which morphological analysis was performed on the plants and the yield components were measured in the field during two consecutive vegetative seasons. The introgression of the 3HS.3BL translocation into the modern wheat cultivar Mv Bodri significantly reduced the plant height due to the incorporation of the dwarfing allele RhtD1b. The presence of the 3HS.3BL translocation in the Mv9kr1 and Mv Bodri wheat background improved tillering and seeds per plant productivity in field experiments carried out in Martonvásár and Keszthely, Hungary.

What types of powdery mildew can infect wheat-barley introgression lines?

This work is a detailed study of the infection of fungal biotrophic pathogens causing powdery mildew diseases on introgression lines originating from the intergeneric hybridisation between wheat and barley (Triticum aestivum L. × Hordeum vulgare L.). Powdery mildew fungi are among the most widespread biotrophic pathogens of plants also and infect dicot and monocot species. Most powdery mildew species are strictly host specific. They colonize only a narrow range of species or one particular host species. The intergeneric hybridisation between wheat and barley could result in expansions of host ranges of the barley powdery mildew. Our experiments covered natural infections in the field and artificial infections under greenhouse conditions. Formae speciales of powdery mildew were identified on the basis of the sequencing results of ribosomal internal transcribed spacer sequences (rDNA-ITS). We identified Blumeria graminis f.sp. tritici isolate 14 (HM484334) on the wheat parent and all wheat-barley introgression lines and B. g. f. sp. hordei isolate MUMH1723 (AB 273556) on the barley parent, respectively. The wheat-barley introgression lines were inoculated with barley powdery mildew under greenhouse conditions. According to our results the added barley chromosomes (or segments) do not cause host range expansion of barley powdery mildew.

Adaptability of winter wheat genotypes originating from composite crosses to organic and low input conditions

One of the biggest challenges for the safe maize production is the yield stability in a wide range of environments with different soil fertility, weather conditions, prevailing pests and diseases as well as cultural practices. In order to achieve it, new hybrids with higher tolerance to biotic and abiotic stress are continuously being created. In order to compare performance of maize hybrids in environments with different levels and types of stress, and relate it to the stalk lodging incidence, we compared performance of 64 maize hybrids obtained by crossing 16 inbred lines with four inbred testers in three different environments. Two environments at same location (Rugvica) differed in crop rotation, and the third environment at location Botinec was considered as dry because of low water capacity of the soil. Mixed models that included all design elements and genetic background of hybrids were used to analyze the effect of lodging on yield in different environments. The results show that stalk lodging had a significant effect on yield, but significant lodging x environment interaction indicates that this effect was rather environment specific.Sweet pepper Istra F1 hybrid was grown in a greenhouse on K rich soil. For evaluation of K antagonism, two K rates (55 and 85 kg ha-1) were applied in a randomized complete block design with four replications. Total number of fruits, total number of BER affected fruits as well as average fruit mass were recorded for each harvest. Fruit and leaf K and Ca content were determined at three plant growth stages (at the stage of the first, third and fifth fruit cluster). Higher K rate gave higher : average fruit mass (169.45 g), total number of fruits per plant (7.95), number of BER affected fruits per plant (3.82), K in leaves (5.44% DM), K in fruits (6.35% DM), but negatively correlated with Ca concentration in fruits (0.57% DM) and leaves (3.24% DM). This resulted in decreased marketable yield of sweet pepper fruits.

Field study of a new interspecific hybrid

With global climatic changes in prospect the challenge of our days is to increase or at least maintain the productivity of crops under less favourable conditions. A feasible proposition is to promote the biological basis of production. Hybridization between related species makes it possible to transfer desirable traits from one species into another (for example resistance to bioticand tolerance to abiotic stresses and enhance adaptation to changed conditions). Especially crosses between cultivated species and their wild relatives can give valuable genetic material for plant breeding programs. Differences were found between genotypes regarding their tolerance to abiotic stress, allowing selection to be made for better tolerance in the course of breeding (Balla et al., 2006). The belief that global climate change will continue and bring more frequent less favourable conditions for crop production, is becoming more widely accepted (Vago et ah, 2006), so we need plant varieties with enhanced stress tolerance. In this study we examined an interspecific hybrid originating from a cross between Triticum aestivum cv. Bankuti 1201 as the female parent and Agropyron elongatum as the male parent bred by Dr. Dezso Szalay and co-workers. Agropyron elongatum is a decaploid species (2n=10x=70), while Triticum aestivum possess six genom (2n=6x=42). The progeny (Fl) was treated with colchicine and developed in fertile amphiploid plants from which the line BE-1 has been produced by Szalay. According to Liszt at ah (2004) this line proved to be a stable amphiploid (2n=56). The aim of this study was to evaluate some characteristics of the newly bred BE-1 line selected from the interspecific hybrid Triticum aestivum cv. Bankuti 1201 x Agropyron elongatum.

Interaction of Nutrient and Water Deficiency on the Development of Rye ( Secale Cereale L) Genotypes

Seedlings of 15 rye (Secale cereale L.) cultivars and lines were evaluated regarding the dry matter accumulation and the content of essential nutrient elements, grown in modified Hoagland nutrient solution in the phytotron of the Agricultural Research Institute in Martonvasar. Osmotic or/and nutrient stresses were imposed by applying PEG or/and 8−1 strength nutrient solution.