Amelioration in Growth and Physiological Efficiency of Sunflower (Helianthus annuus L.) under Drought by Potassium Application

The present study investigated the induced drought tolerance in sunflower through foliar application of potassium (K) at critical growth stages (head formation or achene filling). Five genotypes of sunflower (G-101, SF-187, Hysun-33, Hysun-38, and 64-A-93) were tested for drought tolerance at ?0.55, ?1.36, and ?1.60 MPa osmotic potential using polyethylene glycol 6000. Hysun-33 showed the highest stress tolerance index as calculated from germination percentage, seedling height, root length, and dry matter. This genotype was further evaluated in the field under drought at head formation or achene filling stages, with or without 1% K foliar application. Treatments were arranged in a randomized complete block design with three replicates. Drought at head formation or achene filling stage significantly decreased biological yield, head diameter, plant height, 1000 achene weight, and achene yield as compared to unstressed control. Potassium application significantly improved all the aforementioned parameters and therefore could be a better strategy for ameliorating drought stress in sunflower.     

Influence of nitrogen fertilization on yield and phenolic compounds in wheat grains (Triticum aestivum L. ssp. aestivum)

Nitrogen (N) is an important plant nutrient and is crucial for the plant growth and grain yield formation of field crops such as wheat (Triticum aestivum L. ssp. aestivum). However, little is known about the influence of N on secondary metabolites in wheat grains which are supposed to be beneficial for human health due to their antioxidant potentials. Therefore, we investigated the influence of N fertilization on plant growth and yield performance of winter wheat, as well as on total phenolic concentration, antioxidant capacity, and the accumulation of (in)soluble phenolic acids in wheat grains during the grain‐filling phase. It was found that ferulic acid was the predominant phenolic acid in wheat grains. As expected, higher amounts of N fertilizer led to increasing grain yields, whereas the concentration of soluble ferulic acid decreased. In contrast, insoluble bound ferulic acid, total phenolic content, and antioxidant capacity were not affected by the N treatment. Insoluble phenolic compounds seemed to be less susceptible to variations in N supply.     

Screening for pre- and post-anthesis drought responses in selected bread wheat (Triticum aestivum L.) genotypes

ABSTRACT

Wheat genotypes with pre- and post-anthesis drought tolerance offer enhanced yield gains under water-limited environments. This study determined pre- and post-anthesis drought responses of selected bread wheat genotypes in order to identify and select candidate genotypes for breeding. Fifteen genetically differentiated wheat genotypes were evaluated under non-stressed (NS), pre-anthesis drought stress (PrADS) and post-anthesis drought stress (PoADS) in glasshouse (GH) and field (FLD) environments. Data were collected on agronomic and physiological traits including number of days to heading (DTH), days to maturity (DTM), plant height (PH), number of spikelet per spike (NSPS), number of kernels per spike (NKPS), thousand kernel weight (TKW), grain yield (GY) and canopy temperature (CT). Analysis of variance revealed significant effects of genotypes, environments and their interactions for studied traits. Weak and positive correlations were recorded between GY with PH (r?=?0.47 and 0.32), NSPS (r?=?0.37 and 0.52) and TKW (r?=?0.30 and r?=?0.20) under PrADS and PoADS conditions, respectively. Genotypes SMY-006, SMY-008, SMY-016, SMY-042 and SMY-044 were identified with pre- and post-anthesis drought tolerance and high yield potential and suitable yield-component traits. These are useful genetic stocks for breeding or cultivation in water-limited environments to improve yield gains.     

Effect of nitrogen limitation on antioxidant qualities is highly associated with genotypes of lettuce (Lactuca sativa L.)

Antioxidants are highly beneficial to human health, and their accumulation in lettuce, one of the most popular leafy vegetables, depends on both genetic and environmental factors. Nitrogen(N) availability plays an essential role in regulating antioxidant accumulation, but the influence of genotype × N interactions on the antioxidant qualities of lettuce is poorly understood. Therefore, the present study investigated the variation of growth and antioxidant qualities of 20 lettuce(Lactuca sativa L.) genotypes(10 green lettuce genotypes and 10 red lettuce genotypes) under limited N(low N, LN) conditions and standard N(high N, HN) conditions. For all 20 genotypes, LN conditions reduced shoot(i.e., leaf) growth, but increased plant concentrations of vitamin C,glutathione, and phenolic compounds, with the exception of carotenoids, compared with HN conditions. Because of reduced biomass under LN conditions, not all lettuce genotypes exhibited increased antioxidant yields or total antioxidant capacity yield. The variation in antioxidant quality was primarily genetically determined. Generally, the green lettuce genotypes exhibited more pronounced increases in antioxidant yields and total antioxidant capacity yield than the red lettuce genotypes under LN conditions. These results suggest that even though LN conditions generally tend to improve the antioxidant qualities of lettuce, the extent of this effect is highly dependent on genotype. Therefore, genotype should be given priority in future studies that aim to improve antioxidant qualities in lettuce through N management.     

Allelopathic potential of bread wheat helps in suppressing the littleseed canarygrass (Phalaris minor Retz.) at its varying densities

In this 2-year field study, we investigated the allelopathic effects of three wheat cultivars (Shafaq-06, Faisalabad-08 and Sehar-06) against different density levels (0, 100, 200 and 300 plants m^?2) of littleseed canarygrass (Phalaris minor Retz.). Crop was sown on 1 and 3 December during 2010–2011 and 2011–2012 cropping seasons, respectively. The results showed that wheat cultivar Shafaq-06 produced more phenolic compounds at all density levels of littleseed canarygrass during both years, which caused more inhibition of littleseed canarygrass growth. More suppressive advantage of cultivar Shafaq-06 against littleseed canarygrass was responsible for its better morphological and yield related traits, and grain yield than cultivars Faisalabad-08 and Sehar-06. Among the tested cultivars, cultivar Sehar-06 had minimum allelopathic potential in suppressing littleseed canarygrass. In crux, Shafaq-06 possesses allelopathic potential to suppress littleseed canarygrass and may be used for breeding future wheat cultivars with high allelopathic activity for better weed suppression.     

Antioxidant activity of commercial soft and hard wheat (Triticum aestivum L.) as affected by gastric pH conditions

Phenolic compounds from soft and hard wheat and their milling fractions were extracted into distilled deionized water, and their in vitro antioxidant activities were evaluated. Wheat samples were used as such (nontreated) or subjected to pH adjustment (treated) in order to simulate gastrointestinal pH conditions. The total phenolic content (TPC) was determined using Folin-Ciocalteu's procedure. The total antioxidant activity (TAA) was determined using Trolox equivalent antioxidant capacity assay and expressed as Trolox equivalents. The antioxidant activity of wheat extracts was also evaluated using the beta-carotene bleaching assay, scavenging of 2,2-diphenyl-1-picrylhydrazyl radical, and inhibition of oxidation of human low density lipoprotein cholesterol. The TPC, TAA, and antioxidant potential, evaluated using different methods of wheat samples, were significantly increased following gastrointestinal tract-simulated pH changes. Thus, digestion taking place in the gastrointestinal tract in vivo may also enhance the antioxidant properties of the extracts.     

Potassium efficiency of safflower (Carthamus tinctorius L.) and sunflower (Helianthus annuus L.)

The oil crop safflower may have a certain production potential under low‐input conditions (organic farming, developing countries), where the putatively low nutrient requirement is highly welcomed. However, current knowledge regarding the nutrient use efficiency of safflower as compared to similar oil crops is limited. It was thus the aim of this study to determine the potassium (K) use efficiency of safflower (Carthamus tinctorius L.) as compared to sunflower (Helianthus annuus L.). Safflower and sunflower were cultivated with increasing K supply in a mixture of equal volumes of sand, nutrient‐poor limed soil, and perlite in 5 L Mitscherlich pots. Both species responded strongly to increasing K supply with respect to growth and yield. Safflower out‐yielded sunflower at low K supply, while at high K level, the opposite was observed. Both species accumulated similar amounts of K in shoots at low K supply. Only at extremely low K supply, safflower took up more K than sunflower. However, achene yield of sunflower exceeded that of safflower at optimal and high K supply. Safflower utilized absorbed K more efficiently than sunflower to produce achene yield at suboptimal K supply in terms of both efficiency ratio and utilization index. The efficiency of a crop to use supplied or accumulated K for dry‐matter and achene production was interpreted in terms of Michaelis‐Menten kinetics, specifically addressing the shape of the yield response curve. Indeed, the efficiency of safflower to use K for growth and yield, analogue to a low K_m in enzyme kinetics, was higher than in sunflower, while the K supply or K accumulation required to initiate yield formation in safflower was significantly lower. Similarly, safflower had a lower external K requirement for achene yield than sunflower at low and optimal K supplies. It can be concluded that safflower represents a low‐input crop and outperforms sunflower on soils low in available K. The data analysis also reveals that using just one efficiency indicator is usually not sufficient to adequately describe the K efficiency of the crop under consideration.     

Comparison of Rhizosphere Impacts of Wheat (Triticum aestivum L.) Genotypes Differing in Phosphorus Efficiency on Acidic and Alkaline Soils

A glasshouse study was conducted to compare the rhizosphere characteristics of two wheat genotypes, Xiaoyan54 (XY54) and Jing411 (J411) on two soils. The results showed that supplying phosphorus (P) increased the biomass and P content of two wheat lines significantly on alkaline soil, but P fertilization altered their biomass and P content on acidic soil only slightly. XY54 decreased rhizosphere pH more significantly than J411 on Fluvo-aquic soil without P addition, but similar acidity ability was shown when P applied. On red soil, two wheat genotypes showed similar rhizosphere pH. Two wheat lines showed similar rhizoshphere phosphatase activity on alkaline soil, whereas XY54 demonstrated greater rhizoshphere phosphatase activity than J411 on acidic soil. Rhizoshphere phosphatase activities of two wheat lines on acidic soil were greater than alkaline soil. Therefore, stronger acidity on alkaline soil and greater phosphatase activity on acidic soil are principal rhizosphere mechanisms for XY54 to adapt to low-P soils.     

Effect of nitrogen and wheat residue on cotton (Gossypium hirsutum L.) yield and weed control

Wheat (Triticum aestivum L.) residues and nitrogen (N) management are the major problems in the southern part of Iran where irrigated wheat–cotton (Gossypium hirsutum L.)–wheat rotation is a common practice. A 2-year (2009–2011) field experiment was conducted as a split plot design with four replications at a cotton field (Darab), Fars Province, Iran, to determine the influence of different rates of wheat residue (0%, 25%, 50%, and 75%) incorporation and N rates (150, 200, 300, and 400 kg ha^?1) on weed suppression, yield, and yield components of cotton. Results showed that a higher residue incorporation and a lower N rate improved weed suppression in both years. For treatments receiving 150 kg N ha^?1 and 75% of wheat residues (2250 kg ha^?1), weed biomass and density were significantly lower compared to treatments receiving 400 kg N ha^?1. The highest cotton lint yield (about 2400–2700 kg ha^?1) was obtained by 300 kg N ha^?1 in the absence of residue application, in both years. Incorporation of 25% of wheat residue (750 kg ha^?1) and application of 300 kg N ha^?1 are recommended to guarantee an optimum level of cotton lint yield and weed suppression in a wheat–cotton–wheat rotation in this region.     

Nitrogen Leaching Of Spring Wheat Genotypes (Triticum Aestivum L.) Varying In Nitrogen-Related Traits

Efficient use of nitrogen (N) by wheat crop and hence prevention of possible contamination of ground and surface waters by nitrates has aroused environmental concerns. The present study was conducted in drainage lysimeters for three years (1998–2000) to identify whether spring wheat genotypes (Triticum aestivum L.) that differ in N-related traits differ in N leaching and to relate parameters of N use efficiency (NUE) with parameters of N leaching. For this reason two spring wheat cultivars (‘Albis’ and ‘Toronit’) and an experimental line (‘L94491’) were grown under low (20 kg N ha^?1) and ample N supply (270 kg N ha^?1). The genotypes varied in parameters of NUE but not in N leaching. Grain yield of the high-protein line (‘L94491’) was, on average, 11% lower than that of ‘Toronit’ but among genotypes had significantly higher N in the grain (%), grain N yield, and N harvest index. Nitrogen lost through leaching was considerably low (0.42–0.52 g m^?2) mainly due to low volume of percolating water or the ability of the genotypes to efficiently exploit soil mineral N. There were no clear relationships between N-related genotype traits and N leaching, but across all treatments significantly negative correlations between volume of leachate and the amount of N in the total biomass and grain N yield existed.     

Wounding stress increases the phenolic content and antioxidant capacity of purple-flesh potatoes (Solanum tuberosum L.)

Several abiotic stresses, including ethylene, methyl jasmonate, temperature, light, and wounding, were tested for their ability to induce accumulation of phenolic compounds and antioxidant capacity in purple-flesh potatoes (cv. All Blue). Results indicated that temperature, ethylene, methyl jasmonate, and light treatments did not significantly affect the accumulation of phenolic compounds compared to control samples. Only tubers with low initial anthocyanin levels treated with methyl jasmonate showed approximately 60% anthocyanin accumulation. Wounding induced the accumulation of phenolics compounds and an increase of PAL-activity in sliced tissue compared to the control. Total phenolics increased approximately 60% with a parallel 85% increase in antioxidant capacity. These results show that selection of appropriate abiotic stresses can enhance the nutritional and functional value of potatoes.     

Growth-related changes in wheat (Triticum aestivum L.) genotypes grown under salinity stress

The sensitivity of crop genotypes determines the level of growth reduction by salinity. Effect of salinity levels (7.5 and 15 dihydrate m^?1) using completely randomized design (CRD) with four replications per treatment were compared on germination, chlorophyll content, water potential, ionic sodium and potassium (Na⁺, K⁺) balance, and other growth-related parameters of six wheat genotypes for varietal differences under long-term salinity stress. Chlorophyll contents at flowering stage and yield aspects at maturity of all the wheat genotypes decreased with increasing salinity. The maximum Na⁺ concentration was observed at 7.5 and 15 dS m^?1 in Bhakhar and Saher-2000, respectively, while minimum Na⁺ concentration was observed for 9476. However, the maximum K⁺ concentration and water potential was noticed in 9476 at 7.5 dS m^?1. Careful selection of salt-tolerant genotypes for field crops is an important perspective especially in the developing countries facing salinity problem. Our results revealed that the wheat genotype 9476 performed best regarding growth and physiological parameters compared to other wheat genotypes.     

Alien cytoplasm effects on phytosiderophore release in two spring wheats (Triticum aestivum L.)

Iron (Fe) deficiency is a difficult nutrient problem particularly in crop plants grown on calcareous soils. Recently, phytosiderophore (PS) release has been linked to the ability of graminaceous species and genotypes to withstand Fe-deficiency chlorosis. So enhancing PS release is a critical step to improve iron efficiency of plants grown on iron stressed soils. The effects of alien cytoplasm on PS release in spring wheat were studied by analyzing PS release from twenty wheat genotypes, including two spring wheat 881 and 352-35, and their 18 alloplasmic lines with the participation of cytoplasms from the Aegilops and Triticum species. Different genotypes were grown in iron sufficient and deficient nutrient solution under controlled environmental conditions. PS release rates were determined at two or three days intervals after onset of iron deficiency symptoms by the measurement of iron mobilizing capacity of root exudates from freshly precipitated Fe^III hydroxide. High amounts of phytosiderophores were released from roots of all wheat genotypes without iron supplied, and the amount progressively increased with the development of iron deficiency chlorosis. The results revealed that (1) the release rate of phytosiderophores from roots of common wheat could be considerably influenced by alien cytoplasms. Some alien cytoplasms exerted positive effects, some ones did negative effects, and the other ones had no significant effects. (2) the same alien cytoplasm could affect similarly or oppositely the phytosiderophores release from different wheat. (3) some alien cytoplasms, such as Chinese Spring, Ae. speltoides Tausch and Ae. cylindrica Host showed promising and potential in improving the rate of phytosiderophore release in common wheat. These cytoplasms which showed the desired effect should be given priority in interspecific and intergeneric hybridization to develop and reconstruct the needed wheat cultivars.     

Decomposition of crop residues under laboratory conditions

Abstract. A laboratory study was designed to provide data on the decomposition of rape, sunflower and soyabean residues put in bags buried in soil. The residue bags were removed at intervals during 1 year, analysed for remaining total mass, organic and water-soluble C, water-soluble sugars, as well as for volatile acids and phenolic compounds. The decomposition dynamics of total mass, total organic and water-soluble organic C, and water-soluble sugars were reproduced satisfactorily by a double-exponential model of the first-order type. Generally, no large differences in the rate and magnitude of decomposition among the residues were observed; the greatest losses of both total mass and chemical components occurred in the first month of the study, during which the volatile acids and phenolic compounds disappeared almost completely. Of the three residues, soyabean showed the lowest loss of organic carbon, losing 66% of the original content over the course of the year compared with 73 and 75% for sunflower and rape, respectively.     

Phytochemical quantification and total antioxidant capacities of emmer (Triticum dicoccon Schrank) and einkorn (Triticum monococcum L.) wheat landraces

In this study, samples of 18 ancient wheat (12 emmer, 6 einkorn) and 2 bread wheat varieties grown in different regions of Turkey were examined for their total phenolics and flavonoids, phenolic acids, lutein, total yellow pigment, and total radical scavenging capacities against ABTS cation. Results showed that health beneficial phytochemicals and total antioxidant capacities were generally significantly different in emmer and einkorn wheat groups. Remarkably higher total antioxidant activity (18.31 +/- 1.31 micromol Trolox equiv/g), total phenolics (6.33 +/- 0.98 micromol gallic acid equiv/g), ferulic acid (662.95 +/- 61.07 microg/g), and flavonoids (1.61 +/- 0.34 micromol catechin equiv/g) content were detected in emmer wheat samples (n = 12), suggesting that they may have high potential for utilization as a novel grain, rich in natural antioxidants. In addition, quite high levels of lutein (7.33 +/- 2.43 microg/g) of einkorn samples (n = 6) hold the potential of developing high-lutein bakery products to considerably raise the dietary intake of carotenoids. These findings for ancient wheat varieties are considered to be very useful in breeding programs for selecting and breeding wheat varieties for higher concentration and better composition of health-beneficial phytochemicals.     

Root morphology and shoot growth in seedlings of chia (Salvia hispanica L.)

The use of chia (Salvia hispanica L.) seeds as functional food is increasing worldwide and research on plant traits is important as the crop spreads. The seedling stage has been identified as crucial for establishment, survival, and competition with weeds but information on chia at this stage is scanty, especially regarding root traits. In this study, 8 genotypes of chia: 4 populations (Australia, Mexico, Peru, Basilicata) and 4 breeding lines (G3, G8, G17, WS) were evaluated under controlled conditions at two early stages (six leaves, S-6; ten leaves, S-10) with the aim to assess growth characteristics and variability in root morphological traits. The shoot height and dry matter were measured together with the following root traits: dry matter and architectural parameters characterized through image analysis of root scans: length, surface, average diameter, tips, forks and crossings. Plants showed a greater phenotypic variation at S-6 than at S-10 (average CV?=?40% and 22%, respectively). A high variability was recorded for root biomass, root volume, number of forks and crossings (average CV?=?54, 40, 44 and 48%, respectively), while root diameter showed lower variability (average CV?=?10%). Four principal components explained more than 97% of the total variance and root length, surface area, volume and average diameter contributed mainly to the variability. Cluster analysis showed that genotypes were very different for morphological root traits. Australia and G8 had the most developed root system with longer and coarser roots. Our results could be used in a breeding program for new cultivars with a more vigorous seedling.

     

Genetic variation for phenolic acids concentration and composition in a tetraploid wheat (<Emphasis Type="Italic">Triticum turgidum</Emphasis> L.) collection

Phenolic acid intake through the consumption of whole-wheat foods provides important health benefits associated with reduced risks of cardiovascular diseases and colon cancer. The genetic variation for phenolic acids was extensively studied in common wheat, but a comprehensive survey in tetraploid wheat is lacking. In this study we evaluated the genetic variability for individual and total phenolic acids concentration existing in a large collection of tetraploid wheat (Triticum turgidum L.). A 2-year evaluation was undertaken on the whole-meal flour of 111 genotypes belonging to seven T. turgidum subspecies including cultivars, landraces and wild accessions. Durum cultivars [T. turgidum subsp. durum (Desf.) MacKey], had the highest average concentration of total phenolic acids (828.7 μg g^?1 dm in 2012; 834.5 μg g^?1 dm in 2013) with amounts varying from 550.9 μg g^?1 dm to 1701.2 μg g^?1 dm, indicating a variation of greater than threefold fold. The lowest concentration of phenolic acids was found in T. turgidum subsp. dicoccum (Schrank ex Schübler) Thell. Rivet wheat (T. turgidum L. subsp. turgidum) had phenolic acid concentrations similar to those in durum, but less variation was noted among the accessions. On the other hand, the accessions of the four remaining subspecies showed lower phenolic acid concentrations and variation among the accessions as compared to durum. A total of six phenolic acids were identified across the wheat genotypes. The effects of genotype, year and year × genotype were estimated by ANOVA and resulted significant for all phenolic acids. The ratio of genotypic variance to total variance suggested the possibility of improving phenolic acid content in elite wheat germplasm through appropriate breeding programs. Moreover, significant correlations between phenolic acids and other quality characteristics of the grain were detected.     

Tolerance of chickpea (Cicer arietinum L.) lines to root-knot nematode, Meloidogyne javanica (Treub) Chitwood

The root-knot nematode, Meloidogyne javanica (Treub) Chitwood is an important parasite of chickpea (Cicer arietinum L.). Four chickpea genotypes were evaluated for tolerance to M. javanica in naturally infested fields at three locations. Each genotype was evaluated for number of galls, gall size, root area covered with galls and number of egg masses produced. All the cultivars were susceptible or highly susceptible. Seed yield, weight of 100 undamaged seeds, total dry matter and plant height were compared with checks. Chickpea cultivar Annigeri and a local check were used as nematode susceptible checks in all locations. The four promising nematode tolerant genotypes produced significantly greater yield and total dry matter than the checks in fields naturally infested with M. javanica at three locations. These M. javanica tolerant lines represent new germplasm and they are available in the chickpea genebank at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) bearing the identification numbers ICC 8932, ICC 11152, ICCV 90043 and ICCC 42.     

Changes in the Phenolic Acid Content and Antioxidant Activity During Kernel Development of Corn (Zea mays L.) and Relationship with Mycotoxin Contamination

Corn grain production could be affected by several fungal pathogens responsible for the production of mycotoxins. The aims of this study were to determine the evolution of phenolic acids and total antioxidant activity (TAA) during kernel development and to evaluate their potential protective role in minimizing mycotoxin contamination in six corn genotypes (four open‐pollinated varieties and two hybrids) characterized by a wide array of kernel traits. TAA and free and cell wall‐bound phenolics showed significant differences among corn genotypes at different stages of development, with the highest values found at the beginning of kernel development. Ferulic, p‐coumaric, and caffeic acids were the main cell wall‐bound phenolic acids during kernel development, whereas chlorogenic acid was the main free phenolic acid. A significant negative correlation was observed between deoxynivalenol contamination at harvest maturity and free phenolic acids and TAA at the beginning of kernel development, whereas no significant correlation was observed with fumonisin contamination. In conclusion, free phenolic acids are evidently involved in the resistance mechanism toward deoxynivalenol contamination, whereas their role toward fumonisin contamination was not elucidated under field conditions, implying that components other than phenolic acids may be responsible for this latter type of resistance.     

不同条件育秧提高水稻秧苗抗逆性的研究

稻麦轮作系统中,麦秸还田腐解产生的有毒有害物质可对下茬水稻幼苗产生不利影响,有效减缓或避免其负面影响对于水稻生产尤为重要,而筛选能够提高水稻秧苗抗性的育秧技术不失为重要途径。通过采用5种不同育秧条件对水稻秧苗进行抗性锻炼,以期提高水稻秧苗对麦秸还田条件的抗逆性和适应性,并在移栽后采取相同的栽培措施(氮素和水肥管理)对其进行评估。试验结果表明,干旱及低营养条件下育秧均降低了水稻株高、生物量以及叶绿素含量,且增加了水稻植株丙二醛含量和脯氨酸含量,使水稻的生长发育受到抑制;而施用秸秆、浇施秸秆腐解液以及酚酸混合液进行育秧的处理均增加了水稻株高、地上部鲜重、叶绿素含量、总根长、根表面积、根体积、根尖数、根分枝数和平均根直径,且均降低了水稻植株丙二醛含量和脯氨酸含量,提高了水稻秧苗对麦秸腐解产生负面影响的抗逆性和适应性。通过在水稻育秧期添加适量麦秸、麦秸腐解液或酚酸混合液均可有效提高水稻秧苗对麦秸还田条件的适应性。