Inheritance of the Triple-spikelet Character in a Tibetan Landrace of Common Wheat

The Tibetan triple-spikelet wheat (TTSW) (Triticum aestivum L. concv. tripletum nom. nud.) is a landrace of common wheat collected from Tibet, China. It possesses a genetic stable character of triple-spikelets, and produces more than 50 spikelets and about 150 florets per spike. The plant has normal number of tillers, normal length of spikes, and well-developed seeds. The inheritance of the triple-spikelet trait in TTSW was genetically analyzed. The results indicate that the triple-spikelet character in TTSW is controlled by two recessive genes. Therefore, we suggest designating the genes controlling this character of triple-spikelets as Ts1 and Ts2. These genes could be used for increasing the number of spikelets per spike for high-yield breeding in common wheat.     

Late nitrogen fertilization affects nitrogen remobilization in wheat

A pot experiment with wheat plants was carried out to study how late application of nitrogen (N) fertilizer affects the use of pre‐anthesis N reserves during the grain‐filling period. Increasing doses of N fertilizer were applied (0, 40, and 52 mg N plant^–1), either in two amendments (growth stages GS20 and GS30, according to Zadoks scale) or in three amendments (GS20, GS30, and GS37). The experiment was arranged in a complete randomized three‐block design with 129 plants per treatment. The plants were watered daily, harvested every 2 d between anthesis and maturity, and were separated into roots, leaf sheaths, leaf blades, and ears for further N determination. Grain N concentration improved due to a late N application in GS37 by 14% (higher N dose) and by 7% (further splitting the same N‐fertilizer dose, respectively). The higher the N‐fertilizer dose applied, the greater was the amount of pre‐anthesis reserves in vegetative organs, these reserves became later available for remobilization. Although splitting the same N dose in three amendments did not increase the N reserves, these reserves were more efficiently remobilized allowing an improvement in grain N concentration. The fertilizer management did not change the temporary pattern of N accumulation in the ear, but did induce a change in the amount of N remobilized and in the contribution of each organ (root, leaf sheath, leaf blade) to this remobilization. Late N amendment allowed a greater N availability of leaf blades and ear N reserves (from 20% up to 26% and from 19% up to 22%, respectively) for remobilization towards the grain, decreasing the root contribution from 28% down to 15%, while the contribution of leaf sheaths was maintained around 35% irrespective of the N applied.     

Impact of effective microorganisms and other biofertilizers on soil microbial characteristics,organic‐matter decomposition,and plant growth

Incubation and pot experiments were conducted to investigate the impact of commercially distributed biofertilizers (effective microorganisms [EM], BIOSTIMULATOR, BACTOFIL‐A, and BACTOFIL‐B) on soil microbial‐biomass content and activity, net N mineralization in soil, and growth of Lolium perenne. According to the manufacturers, the products tested are based on microbial inoculants or organic growth stimulants, and are supposed to influence soil microbial properties and improve soil conditions, organic‐matter decomposition, and plant growth. In the incubation experiment (40 d, 20.6°C, 50% maximum water‐holding capacity), EM was repeatedly applied to soil together with different organic amendments (nonamended, chopped straw, and lupine seed meal). Under the experimental conditions of this study, no or only marginal effects of EM on organic C, total N, and mineral N in soil could be observed. In soil treatments without any organic amendment, EM suspension slightly enhanced microbial activity measured as soil CO₂ evolution. In soil with easily degradable plant residues (lupine seed meal), EM suspension had a suppressive effect on microbial biomass. However, comparisons with sterilized EM and molasses as the main additive in EM suspension showed that any effect of EM could be explained as a pure substrate effect without the influence of added living organisms. In the pot experiment with Lolium perenne (air‐conditioned greenhouse cabin, 87 d, 16.8°C, 130 klxh d^–1 light quantity), the products EM, BIOSTIMULATOR, BACTOFIL‐A, and BACTOFIL‐B were tested in soil with growing plants. The products were repeatedly applied for a period of 42 d. Within this study, no effects of the different biofertilizers on mineral N in soil were detectable. There were clear suppressive effects of all tested biofertilizers on microbial‐biomass content and activity. Comparisons with sterilized suspensions showed that the effects were not due to living microorganisms in the suspensions, but could be traced back to substrate‐induced processes.     

Nitrogen rate applied affects dry matter translocation and performance attributes of wheat under deficit irrigation

Crop production in arid/semi-arid regions is restricted by soil moisture and nitrogen (N) deficiencies. Consequently, sufficient levels of N and irrigation are important in improving the crop's productivity. Therefore, a 2-year field experiment was conducted to understand influences of watering techniques namely 300, 500 and 700 mm with contrasting N supply (0, 60, 120 and 180 kg ha^?1) on wheat cv. “landrace” productivity, dry matter translocation (DMT) and contribution of pre-anthesis assimilates to the grain (CPAAG, %). Experiments were conducted each year using a split-plot design with three replications at a private farm, North Hamedan Province, Iran. Accordingly, when 500/700 mm water was applied, CPAAG values were higher than those obtained after applying 300 mm water, i.e. 49.99 and 45.45 vs. 40.13%. The highest productivity in terms of grain yield, grain N concentration, nitrogen harvest index, special products analysis division and protein content was achieved in normal deficiencies of irrigation and N. This was further supported by a higher leaf area index, crop growth rate and N uptake of such treatment. Meanwhile, co-application of 120 kg N and 500 mm water significantly improved DMT, water and N use efficiency, and it was the optimal scheme for wheat production.     

Response of wheat genotypes to foliar spray of ZnO and Fe2O3 nanoparticles under salt stress

This study evaluated the effects of iron oxide (Fe₂O₃) and zinc oxide (ZnO) on two wheat genotypes (Kavir and Tajan) at three levels (0, 75, and 150 mM sodium chloride (NaCl)) of salinity. Spray treatments included two forms of normal and nanoparticles of Fe₂O₃ and ZnO, a mixture of nanoparticles of Fe₂O₃ and ZnO (2 g L^?1) and a non-spray treatment. The pot experiment was arranged as factorial in a randomized complete block design with four replications. Two forms of Fe₂O₃ and ZnO significantly accelerated plant height, leaf area, shoot dry weight, and the concentration of iron (Fe) and zinc (Zn) in comparison with non-spray treatment. The highest plant height and leaf Fe concentration belonged to Fe₂O₃ nanoparticles; however, it seems that the spray of nanoparticles may not be superior compared with normal forms in alleviation of salinity impacts.     

Shift of grain protein composition in bread wheat under summer drought events

Climate change bears the risk of more frequent drought stress in the northern hemisphere with more frequent early summer drought events affecting main grain crops. Winter wheat (Triticum aestivum L.) is susceptible for such drought events at the flowering and grain filling stages. After drought, the grain yield decrease of three hybrids was about 20% lower compared to three wheat lines analyzed. Wheat grain proteins are classified into four main components such as albumin and globulin, gliadin, and glutenin. The latter two are closely related to the baking quality of flour and might be affected by drought. However, detailed knowledge about the influence of drought on the synthesis of specific storage protein fractions is scarce. By analyzing the grain protein fractions by means of SDS‐PAGE technique, we detected an increase in grain protein content as well as in HMW and some LMW glutenin sub‐fractions. The glutenin fraction seems to be most variable in gene expression under different environmental scenarios such as drought. However, the protein yield as well as the grain yield may be strongly decreased, which might be not acceptable in practice.     

Somaclonal variation in three Argentinean varieties of Triticum aestivum with different karyotypic instability*

Three cultivars of wheat showing different levels of spontaneous karyotypic instability were studied regarding their stability in vitro for a number of characters, i.e. chromosome structure, gliadin pattern, glume and grain colour, awn type, chlorophyll pigmentation and plant morphology. The progenies of somaclones derived from immature embryos of both aneuploid and euploid plants were used in this study along with foundation seeds and a large number of their sexual progeny in order to discriminate between pre-existent variability and any novel variation induced by the in vitro culture. Only one translocation not described before and a new gliadin pattern were detected which could be ascribed to the effects of tissue culture, suggesting that this technique is not effective for inducing novel variation for breeding purposes in wheat.     

Regeneration of fertile doubled haploid plants from colchicine-supplemented media in wheat anther culture

The effect of colchicine added to induction medium for the production of fertile doubled haploid plants after in‐vitro anther culture was studied in wheat, Triticum aestivum L. For this, one winter and two spring wheat varieties were used. Anther cultures of the three genotypes were treated with 0.03% colchicine for 3 days at the beginning of microspore induction. Colchicine had no significant effect on anther response and embryoid production of the genotypes examined. However, in the winter wheat genotype ‘Mv Szigma’, colchicine caused a significant reduction in microspore‐derived structures. A significant decrease was also observed in plant regeneration ability of two genotypes (‘Vergina’ and ‘Acheloos’) after colchicine treatment. In addition, a significant reduction of the albinos produced was observed in all genotypes after olchicine treatment. In contrast, the regenerants obtained from the colchicine‐supplemented induction media produced significantly higher percentages of fertile plants in all genotypes. However, the level of fertility, was significantly different among the fertile plants obtained. This, together with the observation that in the case of the winter wheat variety the colchicine treatment resulted in 100% completely fertile plants with a high seed‐setting ability indicate that there is space for further improvement of the method when it is applied to spring cultivars. Finally, the increased number of seeds per 100 plated anthers obtained from all three genotypes after colchicine treatment, clearly demonstrates that the addition of colchicine to induction medium was superior to the conventional anther culture method and it could therefore be introduced into wheat breeding programmes.     

Utilization of deletions to localize a gene for resistance to the cereal cyst nematode, Heterodera avenue, on an Aegilops ventricosa chromosome

A previous RFLP analysis showed that the Aegilops ventricosa chromosome 6M^V which compensates for the absence of 6D in 6M^V (6D) wheat substitution lines was a 2/6 translocated chromosome, either 2S–6S.6L or 2S–6L.6S. The distal part of its long arm consists of a translocated segment belonging to homoeologous group 2. Chromosome 6M^V carries a gene(s) for resistance to cereal cyst nematode. In order to define the part of 6M^V (2S or 6S or 6L) involved in this resistance, addition lines with a 6M^V deleted either for its short arm or for the distal part of its long arm were evaluated. It was shown that the gene(s) is carried by the group 2 translocated segment. The hypothesis that the gene(s) could be allelic to Cre2, another gene conferring resistance to the nematode introduced into the wheat complement from Ae. ventricosa is discussed.     

Aluminium tolerance in wheat: correlating hydroponic evaluations with field and soil performances*

The objective of this study was to correlate root length of wheat (Triticum aestivum L.) genotypes grown in Al-containing, acidic hydroponic solutions, with root weights from acid-soil experiments and field scores from Brazilian acid-field trials. A total of 43 wheat genotypes, primarily from Brazil, were evaluated by growing seedlings for 4 days in hydroponic solutions containing 0.0–4.0 mg/l Al. The root growth rate of all the genotypes was reduced with the addition of Al to the solution and the Al-sensitive and Al-tolerant wheat genotypes were clearly identified. Genotypes with intermediate Al-tolerance levels showed variable root lengths in response to Al stress. Correlations between root length or a root tolerance index (RTI) in the Al solutions versus acid-soil experiments and acid-field trials were highly significant (r = 0.71–0.85, P < 0.01). The most significant correlation was observed among seedlings grown in 1 mg/1 Al. This study presents evidence that this short duration and simple screening technique provides a highly significant correlation with previous acid-soil Al-tolerance evaluations. Furthermore, the data obtained suggest that hydroponic screening of wheat seedlings for Al tolerance may be used in breeding programmes or in screening germplasm collections.