Improving the performance of bread wheat genotypes by managing irrigation and nitrogen under semi-arid conditions

Wheat (Triticum aestivum L.) productivity is generally affected by water limitation and inadequate nitrogen supply especially under semi-arid environment. The current study was conducted to determine whether the crop yield and irrigation water use efficiency (IWUE) could be manipulated through alteration of nitrogen and irrigation application. To meet the desired objectives, a two-year field study was carried out in 2013–2014 and 2014–2015, in a split-split plot arrangement with three factors i) irrigation in main plots, ii) nitrogen in sub-plots, and iii) twenty genotypes in sub-sub plots on a sandy loam soil. The analysis of variance revealed that the wheat performance was affected by genotypes and alteration of irrigation and nitrogen application with respect to IWUE and final grain yield. IWUE under water stress conditions was observed 56% higher than normal irrigated. Much higher values of IWUE under water stress indicated that the existing optimum water requirements of the crop needs to be revaluated. The regression model indicated that addition of nitrogen and irrigation patterns along with morphological traits cannot explain variation in yield related traits more than 65% under semi-arid conditions. Therefore, for better crop yields in semi-arid environment, more physiological parameters should be considered in evaluation of yield.     

Fractionation method for the determination of the root length of field-grown wheat

Abstract

Extract

Studies on the root system which are essential to understand the nutrient and water uptake by plant, are very difficult because the root system in the soil can not be observed directly unlike the shoot system. Even basic parameters, such as root length and root surface area cannot be measured easily.     

The yields,agronomic, and nitrogen use efficiency traits of wheat cultivars in north China under N-sufficient and -deficient conditions

In this study, the yields, yield components, agronomic, and nitrogen use efficiency (NUE) traits of the eighty-four winter wheat cultivars were investigated under nitrogen (N)-sufficient and -deficient conditions. Dramatic variations were observed in the yield and agronomic traits among the cultivars. Based on absolute yields under the N treatments, the cultivars were categorized into N efficiency groups of high, close high, medium, and low, in which the high efficiency group cultivars generally exhibited improved agronomic traits under these contrasting N-supply conditions. Additionally, the wheat cultivars were classified into various N response groups, including toleration, relative toleration, sensitive, and most sensitive based on the ratios of yield under N deficiency to that under N sufficiency. Regression correlation analyses revealed that straw biomass, total biomass, grain N amount, and straw N amount were significantly correlated with yield, suggesting that these traits can be acted as indices in evaluating yield potentials in wheat.     

Effects of zinc activity in nutrient solution on uptake,translocation, and root export of cadmium and zinc in three wheat genotypes with different zinc efficiencies

The interactions of zinc (Zn) and cadmium (Cd) in uptake and translocation are common but not consistent. We hypothesized that Cd²⁺ and Zn²⁺ activity in the apoplasmic solution bathing root-cells could affect Zn accumulation in plants dependent on the wheat genotype. This hypothesis was tested using seedlings of two bread wheat genotypes (Triticum aestivum L. cvs. Rushan and Cross) and one durum wheat genotype (Triticum durum L. cv. Arya) with different Zn efficiencies grown in chelate-buffered nutrient solutions with three Zn²⁺ (10^?11.11, 10^?9.11, and 10^?8.81?µM) and two Cd²⁺ (10^?11.21 and 10^?10.2?µM) activity levels. Increasing Zn²⁺ activity in the nutrient solution significantly increased Zn concentration in root and shoots of all three wheat genotypes, although the magnitude of this increase was dependent on the genotype. Cadmium decreased Zn concentration in roots of “Cross” while it had no significant effect on root Zn concentration in “Rushan.” At Zn^2+?=?10^?11.11?µM, Cd decreased shoot Zn concentration in “Arya” whereas it increased shoot Zn concentration at Zn^2+?=?10^?8.81?µM. Cadmium increased shoot Zn concentration of “Rushan” and “Cross” at Zn^2+?=?10^?8.81?µM but it had no significant effect on shoot Zn concentration of these genotypes at Zn^2+?=?10^?11.11?µM. The zinc-inefficient genotype “Arya” accumulated significantly more Cd in its root in comparison with “Cross” and “Rushan.” Cadmium concentration in roots of “Arya” was decreased significantly with increasing Zn activity. The effect of Zn on accumulation of Cd in roots of “Cross” and “Rushan” was dependent on the dose provided, and therefore, both synergistic (at Zn^2+?=?10^?9.11?µM) and antagonistic (at Zn^2+?=?10^?8.81?µM) interactive effects were found in these genotypes. Zinc supply increased the Zn concentration of xylem sap in “Cross” and “Rushan” whereas Zn content in xylem sap of “Arya” was decreased at Zn^2+?=?10^?9.11?µM and thereafter increased at Zn^2+?=?10^?8.81?µM. Cadmium treatment reduced Zn concentration in xylem sap of “Arya,” while it tended to increase Zn content in xylem sap of “Cross.” At Zn-deficient conditions, greater retention of Zn in root cell walls of Zn-inefficient “Arya” resulted in lower root-to-shoot transport of Zn in this genotype. Results revealed that the effect of Cd on the root-to-shoot translocation of Zn via the xylem is dependent on wheat genotype and Zn activity in the nutrient solution.     

Functional traits associated with nitrogen use efficiency in wheat

The association between functional traits and nitrogen use efficiency (NUE) was investigated to assist the breeding of nitrogen (N) use-efficient bread wheat (Triticum aestivum ssp. aestivum) varieties. This study combined results from a climate chamber experiment involving 41 spring wheat varieties and a field experiment involving six winter and six spring wheat varieties grown with and without the application of mineral N fertiliser. The climate chamber experiment was analysed by partial least squares (PLS) regression, with several predictors and NUE as response, to identify traits related to NUE. Specific hypotheses were then tested in the field experiment. The PLS indicated six traits of particular importance for overall NUE: leaf chlorophyll (SPAD value) of the top leaf at stem elongation, grains ear^?1, ears pot^?1, straw biomass pot^?1, days between emergence and anthesis, and days between emergence and completed senescence. In the field experiment, the SPAD value of flag leaves of winter wheat around anthesis was positively correlated with NUE and total grain N, at both N levels. Fast development was positively correlated with high NUE and N uptake efficiency in spring wheat. Early senescence of the flag leaf was positively correlated with grain N concentration and negatively correlated with grain-specific N efficiency in winter wheat at low N fertilisation levels. The results indicate that high SPAD value of the top leaf might be a candidate trait that could be used in wheat breeding for improved NUE, while genetic variation in senescence could possibly be used to tailor varieties for different end-use quality when grown at low N. More studies are needed to validate these findings in other environments and for other genotypes.     

Effects of P fertilization level on phosphorus uptake and agronomic traits under deficit irrigation in winter wheat (T. aestivum L.)

Abstract

Enhancing the phosphorus (P) use efficiency is critical for the sustainable cultivation of winter wheat. In this study, we investigated the effects of P fertilization level on plant P-uptake and agronomic traits under deficit irrigation, by using two wheat cultivars sharing contrasting water responses (i.e., Jimai 585 and Shimai 22). The high P level treatment (P120) improved plant biomass and P accumulation at each growth stage, grain yields, P remobilization amount to grain (PRA), P remobilization rate (PRR), and P contribution rate (PRR) of the cultivars with respect to the low P treatments (i.e., P90 and P60). Compared with Jimai 585, a cultivar acclimated to affluent water, the drought tolerant cultivar Shimai 22 exhibited similar behaviors on plant biomass, P-associated traits at each stage, and agronomic traits at maturity under P120. However, Shimai 22 was more improvement on P-associated and agronomic traits than Jimai 585 under P60 and P90. P contents were increased whereas moisture contents decreased in soil profile treated by P120 with respect to those by P60. Meanwhile, the soil profile cultivated by Shimai 22 displayed reduced moisture and P contents under P deprivation (i.e., P90 and P60) respect to that by Jimai 585, suggesting the contribution of more consumption of soil P and water storage to improved agronomic traits of Shimai 22. Together, our investigation suggested that suitable P input management positively mediates plant P-associated traits and grain formation capacity under deficit irrigation by improving supply and internal translocation of P across tissues in winter wheat plants.     

Contributing traits for nitrogen use efficiency in selected wheat genotypes and corollary between screening methodologies

ABSTRACT

Nitrogen uptake being part of nitrogen use efficiency (NUE) is largely decided by root traits. Root traits variability has hardly been explored by breeders mainly because of difficulties in scoring. The hydroponic system requiring lesser space for precise phenotyping of large numbers of genotypes independently of the growing season can be a suitable alternative. However, the effectiveness of hydroponic screening methods needs to be verified under the soil condition of the field or pot. In the present study, root traits and NUE were investigated in 19 genotypes under two conditions (hydroponic and pipe filled with soil). Both environments revealed large variability for root traits and NUE under high and low N conditions establishing the absence of any direct selection for these traits in the past. Under both sets of experimentation, NUpE was largely responsible for improved nitrogen efficiency mainly because of higher root biomass. The significant association between the two screening methods i.e. hydroponic and pot filled with soil under both low and high N condition support large scale screening for root traits under hydroponic condition.     

黑龙港低平原高产田小麦追肥研究

在严重干旱的 1999～ 2 0 0 0年 ,采用 3个品种 ,3个追肥量 ,3个追肥时期和 3次重复的完全组合设计 ,对大运河以东黑龙港低平原区高产田小麦春季追氮时期和追氮量进行了系统研究。结果表明 :春季追肥时期宜晚 ,第一次肥水在 4叶 1心到 5叶 1心期为好 ,追肥量以尿素 75kg/hm2 为高限 ,甚至可以考虑不追肥。     

Effect of silicon fertilizers on silicon accumulation in wheat

The effect of fertilization with silicon (Si) compounds on accumulation of Si in wheat (Triticum aestivum L.) has been studied. Wheat plants were grown under identical growing conditions, but subjected to fertilization with various Si compounds (pyrolitic fine silica particles [aerosil®], sodium silicate, silica gel), and the Si content of the above ground plants was analyzed via X‐ray microanalysis (EDX) and atomic‐absorption spectroscopy (AAS). Silicon was predominantly deposited in the epidermis cells of the leaves and their cell walls. The efficiency of the Si compounds used as fertilizers to augment the Si content of the plants increased in the order sodium silicate > silica gel > aerosil® and thus seemed to correlate with the ease of formation of orthosilicic acid from these compounds.     

Radiation use efficiency of winter wheat in different planting patterns and irrigation frequencies in the North China Plain

Winter wheat grain yield is connected with radiation use efficiency (RUE). A suitable planting pattern and irrigation strategy are essential for optimizing RUE. In order to investigate the effects of planting patterns and irrigation frequency on winter wheat RUE, a field study was conducted with two planting patterns and three irrigation frequencies. The two planting patterns were wide-precision (WP) and conventional-spacing (CS). The three irrigation frequencies were irrigated 120 mm at jointing stage, 60 mm each at jointing and heading stages, and 40 mm each at jointing, heading, and milk stages. The results showed leaf area index (LAI) was significantly (P < 0.05) higher in WP than in CS. In addition, the LAI in WP decreased with the increase in irrigation frequency. Under the same irrigation frequency, the photosynthetic active radiation (PAR) interception and dry matter were higher in WP than in CS. In WP, reduced irrigation frequency significantly increased the PAR interception at 60 cm above the ground surface. The largest grain yield and highest RUE was found in WP when plants were irrigated twice. The results indicate WP in combination with irrigated 60 mm each at jointing and heading stages maximized the winter wheat grain yield and RUE.     

Mathematical model for the analysis of irrigation water and fertilizer management for spring wheat in the semiarid area of West Liaoning,China

Soybean plants (Glycine max L. cv. Akisengoku) were grown in water culture in a greenhouse. At the pod-setting and pod-filling stages, plants were subjected to stem-ringing or treated with high concentration of nitrate. Respiration and N₂ fixation (acetylene reducing activity) were studied in individual nodules along with the concentrations of ATP and magnesium.

There was a high positive correlation between respiration activity and acetylene reduction in soybean nodules. The maintenance respiration in mature nodules corresponded to a CO₂ evolution of 5.5 µmol/g F.W., and the respiratory cost for nitrogen fixation was estimated at 2 mg C liberated/mg N fixed, though this value was probably underestimated due to CO₂ fixation by the nodules. For the nitrogenase activity there was a threshold value of ATP concentration at around 0.15 µmol/g F.W., and the activity increased up to around 0.35 µmol/g F.W., beyond which the ATP concentration did not increase unlike the nitrogenase activity. The values for the magnesium concentration in the nodules detected in the present experiments were above the optimum level.     

Tillage effects on soil properties and wheat cultivars traits

Information regarding the evaluation of tillage effects on soil properties and rainfed wheat (Triticum aestivum L.) cultivars of Iranian fields is not available. Therefore, this research was conducted in Sanandaj (west of Iran) using a randomized complete block design in a split-plot arrangement. Three types of tillage including conventional tillage (moldboard plow to soil depth of 30 cm plus disk harrow twice), minimum tillage (chisel plow to soil depth of 15 cm plus disk harrow once) and no-tillage are assigned to the main plots. Wheat cultivars (Sardari and Azar2) were randomly distributed within the subplots in each tillage system. Results showed that the greatest bulk density and cone index were found in the minimum tillage and no tillage systems. The highest rate of grain yield was obtained in the minimum tillage system. The grain yield of Sardari cultivar (1624.1 kg ha^?1) was significantly greater than that of Azar2 (1572 kg ha^?1). Minimum tillage improved soil physical properties and wheat growth compared with the other tillage systems. No tillage increased microbial biomass carbon and bacteria number in soil compared with the other tillage systems. We conclude that using minimum tillage for Sardari cultivar will be more effective compared with other treatments.     

小麦生长素响应因子TaARF6转基因烟草植株分子鉴定

【目的】生长素响应因子(ARF)在介导生长素信号传递和调控下游生长素响应基因的表达中发挥着重要功能。本文旨在以在富集丰磷特异表达基因的小麦根系cDNA差减文库中鉴定的1个ARF类别的家族成员TaARF6为基础,对该基因cDNA序列、分子特征、不同供磷水平下该基因在根、叶中表达模式及遗传转化TaARF6对丰磷和缺磷条件下植株形态的影响进行较全面研究,阐明该小麦生长素响应因子基因介导不同供磷水平下对植株生长特性的影响。【方法】采用生物信息学工具预测TaARF6编码蛋白特征; 采用溶液培养法培养丰、缺磷处理小麦幼苗,采用半定量RT-PCR技术鉴定TaARF6在丰、缺磷处理下的表达特征。采用DNA重组技术构建将TaARF6编码阅读框融合至表达载体中的表达质粒,利用农杆菌介导的遗传转化法建立超表达TaARF6转基因烟草植株。采用琼脂培养和溶液培养法,培养丰、缺磷不同供磷水平下野生型植株和转基因烟草植株,进而利用常规分析方法鉴定不同磷水平下植株长势、根系和茎叶生物量和植株根叶形态及性状。【结果】1)TaARF6编码生长素响应因子(ARF)型转录因子,编码蛋白中含有ARF家族成员具有的保守结构域。该基因在氨基酸水平上与源于短柄草BdARF6和源于水稻的OsARF6具有高度同源特征。表达分析表明,TaARF6在根、叶中均呈典型低磷下表达下调、复磷后表达再度回升模式,表明该基因表达受到外界供磷水平的调节。2)遗传转化结果表明,在正常生长和低磷逆境下,与野生型植株相比,转基因烟草株系幼苗和植株形态明显增大。3)丰、缺磷不同供磷水平下,与未转化的野生型(WT)对照植株相比,转基因系(Line 3 和Line 5)植株幼苗和植株根系、茎叶和单株鲜、干重均较野生型显著增加。此外,与WT相比,转基因系植株根系数量增多、主侧根长度、根体积、叶面积和根冠比增加。【结论】TaARF6编码典型的生长素响应因子,其编码蛋白具有生长素响应因子特有结构域。TaARF6对环境中的低磷胁迫逆境能产生明显应答。上调表达TaARF6基因,具有增加植株根、叶鲜、干重和改善根叶及植株形态的生物学功能。本研究表明,通过对植株体内生长素响应基因的转录调控,TaARF6在介导植株不同供磷水平下的根叶形态建成和干物质累积过程中发挥着重要作用。     

Senescence of the flag leaf and grain yield following late foliar and root applications of phosphate on plants of differing phosphorus status

The balance between leaf senescence, induced by phosphorus deficiency, and grain growth was examined in wheat plants grown in sand with high (control) and low phosphorus (low‐P) nutrition. Foliar applications of P were made prior to anthesis and at early and mid grain development. Low‐P plants were also given an additional dose of P via the roots at mid grain development.

Foliar applications of P had no effect on leaf function (net CO₂ exchange rate), or grain development in control plants. However, P applied to the flag leaf of low‐P plants delayed senescence and thus increased leaf area duration, but this did not result in a significant increase in grain yield per ear. Phosphorus applied to the ear surface (the glumes) of low‐P plants increased the concentration of P in the grain, but did not increase the number of cells per grain, or the grain yield per ear. The late application of P via the roots also delayed senescence in low‐P plants, but did not cause an increase in yield.

These experiments indicate that grain growth in low‐P plants is not limited by the level of supply of photosynthate, or the availability of P during the actual period of grain development. Phosphorus translocated to the grain late in plant development is used inefficiently in plants that are adequately supplied with phosphorus and in plants suffering from P deficiency.     

The role of root plasma membrane ATPase and rhizosphere acidification in zinc uptake by two different Zn-deficiency-tolerant wheat cultivars in response to zinc and histidine availability

ABSTRACT

We investigated the effect of histidine (His) and Zn deficiency on H⁺-ATPase activity and H⁺ release from wheat roots. Two bread wheat (Triticum aestivum L. cvs. Kavir and Back Cross Roshan) were grown in a nutrient solution for four weeks before being transferred to treatment solutions consisting of two concentrations of His (0 and 50 µM) and two concentrations of Zn (0 and 10 μM). The Zn-only and the Zn+His treatments were observed to release more H⁺ in the root media than did the control ones, with the highest achieved under the Zn+His treatment which was roughly 2.1 times higher than that under the control conditions. The H⁺ release from wheat roots increased slightly but significantly in the presence of only His when compared with the control solutions. The hydrolytic and transport activities of H⁺-ATPase were affected by both Zn deficiency and His supply. In both cultivars, application of Zn and His resulted in a higher hydrolytic activity of H⁺-ATPase when compared with the control solutions. The highest hydrolytic activity of H⁺-ATPase in the root plasma membrane vesicles was achieved with the Zn+His treatment. The ‘Back Cross Roshan’ exhibited a higher (PM) H⁺-ATPase activity and H⁺ pumping than did ‘Kavir’.     

Response of selected drought tolerant wheat (Triticum aestivum L.) genotypes for agronomic traits and biochemical markers under drought-stressed and non-stressed conditions

ABSTRACT

Genetic improvement of wheat for drought tolerance can be achieved by developing suitable ideotypes with enhanced yield-response associated with agronomic traits and biochemical markers. The objective of this study was to determine drought response of elite drought tolerant wheat genotypes using agronomic and biochemical traits to select promising lines for breeding. Fourteen wheat genotypes selected from the International Maize and Wheat Improvement Center’s heat and drought tolerance nursery and one standard check variety were evaluated under drought-stressed (DS) and non-stressed (NS) conditions using a randomised complete block design in three replications. Significant (P?<?0.05) genotype, drought condition and genotype?×?drought condition interaction effect were detected for the tested traits suggesting differential response of genotype for selection. Grain yield positively correlated with sucrose (r?=?0.58; P?<?0.05), fructose (r?=?0.52; P?<?0.05) and total sugar (r?=?0.52; P?<?0.05) contents under NS condition and with sucrose (r?=?0.80; P?<?0.001), total sugar (r?=?0.84; P?<?0.001) content, proline content (r?=?0.74; P?<?0.001) and number of grains per spike (r?=?0.58; P?<?0.05) under DS condition. Genetically unrelated wheat genotypes such as SM04, SM19, SM29, SM32, SM45 and SM97 possessing key agronomic and biochemical traits were selected for cultivar development for drought-stressed environments.     

施硫对小麦籽粒形成过程中蛋白质与巯基、二硫键的含量及加工品质的影响

在土壤耕层有效硫含量为728 mg/kg的条件下,选用不同冬小麦品种济麦20、淄麦12、鲁麦21和山农1391为试验材料,研究了施用硫肥对小麦不同穗位和不同粒位子粒蛋白质与巯基、二硫键含量及加工品质的影响。结果表明,施用硫肥对上部穗位粒的蛋白质含量的提高作用大于其他穗位粒; 增加了高蛋白含量品种济麦20和淄麦12 的弱势粒子粒蛋白质含量,增加了上部小穗位子粒和中部穗位强势粒的巯基含量,提高了不同穗位子粒二硫键含量; 而对不同粒位子粒二硫键含量的影响则因品种而异。施用硫肥使小麦面粉湿面筋含量、面团形成时间、稳定时间和粉质评价值均有一定提高,但不同品质指标对施用硫肥的反应存在差异。与子粒形成过程中蛋白质含量的变化相反,巯基的含量变化呈先升后降的规律; 二硫键的含量变化趋势与蛋白质含量的变化相似,但最小值出现时间略有延迟。     

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.     

Effect of phosphate and sulfate fertilizers on selenium uptake by wheat (Triticum aestivum)

The objective of this study was to investigate whether oxyanionic phosphate (P) and sulfate (S) fertilizer management could influence selenium (Se) uptake by wheat (Triticum aestivum) in medium and high Se areas. Field studies were established at two locations for two growing seasons in central South Dakota, USA. Phosphate fertilizer was applied using three different methods (banded with seed, surface-broadcasted in the fall, or surface-broadcasted in the spring) using six different P rates. Sulfate fertilizers were broadcasted at four rates in the fall. Selenium concentration in wheat grain was significantly influenced by the interaction of P application methods and rates, but it was dependent on location. Grain Se concentration decreased in high Se availability soil when P fertilizer was applied, due to the dilution effect. Grain Se concentration and uptake was significantly decreased as S applications increased due to the competition effect, but the depression was apparent in high Se availability soil. The results from this study showed that P and S fertilizer management can influence Se level in wheat grain grown in naturally high Se areas, even though overall grain Se level was strongly associated with location variation.