Incidence of nitrogen fertilization and nitrogen/sulfur complementary fertilization on protein accumulation, yield, and end-use quality of bread wheat cultivars

Selecting low-nitrogen(N)-tolerant maize hybrids represent an effective approach to enhancing nitrogen use efficiency grain yield. However, the impact of nitrogen fertilization on protein accumulation in low-N-tolerant hybrids remain insufficiently explored. In this paper, a two-year field orientation trial was conducted at four nitrogen fertilizer rate with the different low-N-tolerant maize hybrids. The effect of nitrogen fertilization on the accumulation of protein and its fractions different kernels positions of different low-N-tolerant maize hybrids was studied. The results showed that the protein yield of ZH311 maize kernels was significantly higher than that of XY508, especially under low-N conditions (0N and 150N), and was 25.7%-36.2% higher than that of XY508. There was a significant correlation between protein yield and the accumulation of crude protein and protein fractions. Compared with XY508, the crude protein of ZH311 entered the rapid growth stage later and lasted for a relatively shorter period, but it was 50.8%-53.0% higher due to its higher accumulation rates (v2 and v3) in its middle and late stages, especially in the apical grains. Under low-N conditions, the difference in crude protein accumulation between the apical and basal-middle kernels of ZH311 was only 4.3-8.2%, whereas the difference in XY508 was 29.9-37.3%, suggesting that low-N-tolerant maize hybrids improve protein yield by increasing the accumulation of proteins and their fractions in the apical kernels. Nitrogen fertilization had a greater effect on protein accumulation and yield in XY508, especially on the top kernel and protein yield. In the future, more attention should be paid to the effect of apical kernels when breeding high-quality maize hybrids tolerant to low nitrogen.

Two factorial experiments based on randomized complete block design (RCBD) with three replications were conducted in 2007 and 2008, to evaluate grain development (four harvests) and rate and duration of oil and protein accumulation in three soybean cultivars (‘Williams’, ‘Zan’ and ‘L17’) under a non-saline (control) and three saline (3, 6 and 9 ds/m NaCl) conditions. Six seeds were sown in each pot filled with 900 g perlite, using 144 pots for each experiment. After emergence, seedlings were thinned and 4 plants were kept in each pot. Rate of oil accumulation up to maturity was not significantly affected by salinity. With increasing salinity, rate and percentage of protein accumulation, duration of oil and protein accumulation and oil and protein content per grain decreased, but oil percentage increased. Oil and protein yields per plant decreased as salinity increased. These reductions were mainly attributed to the short duration of protein and oil accumulation and grain yield per plant under saline conditions. ‘Williams’ had the highest rate and duration of protein accumulation and rate of oil accumulation, but ‘L17’ had the highest grain yield per plant. Consequently, differences in protein and oil yields per plant between these two cultivars were not statistically significant. However, ‘Zan’ had the lowest protein and oil yields, due to the lowest grain yield per plant.

High temperature is a major determinant of grain growth and yield formation in wheat. The present study was undertaken to investigate the effects of high temperature regimes on the activities of key regulatory enzymes involved in starch and protein accumulation in grains of two winter wheat (Triticum aestivum L.) cultivars Yangmai 9 and Xuzhou 26 with different protein contents. Four day/night temperature regimes of 34 °C/22 °C, 32 °C/24 °C, 26 °C/14 °C and 24 °C/16 °C were established after anthesis, resulting in two daily temperature levels of 28 °C and 20 °C and two diurnal temperature differences of 12 °C and 8 °C. The activities of glutamine synthase (GS) in flag leaves and glutamate pyruvic aminotransferase (GPT), sucrose synthase (SS), soluble starch synthase (SSS) and granule‐bound starch synthase (GBSS) in grains were measured during the periods of grain filling. High temperature reduced both content and yield of starch in grains, while enhanced protein content and reduced protein yield in grains. High temperature significantly enhanced the activities of SS and GBSS on 14 days after anthesis (DAA). High temperature affected SSS slightly in Yangmai 9, but reduced SSS activity markedly in Xuzhou 26 on 14 DAA. However, at the middle and late stages of grain filling, high temperature reduced the activities of SS, GBSS and SSS significantly in the two wheat cultivars. High temperature reduced GPT activity in grains in the two wheat cultivars, but reduced GS activity in flag leaves of Yangmai 9 and enhanced GS activity of Xuzhou 26 on 14 DAA. In addition, under the same high temperature level, SS activity was higher at 34 °C/22 °C, whereas the activities of SSS and GBSS were higher at 32 °C/24 °C. Also, diurnal temperature differences affected GPT and GS activities differently between the two cultivars. Under optimum temperature level, the activities of key enzymes for starch and protein synthesis were higher at 26 °C/14 °C. The activities of SS, SSS and GBSS significantly correlated with starch accumulation in grains, except for GBSS activity to starch content on 14 DAA. GPT activity was positively correlated with protein yield, and GS activity was negatively correlated with protein yield on 14 DAA, while the activities of both GPT and GS were negatively related to protein content in grains.

A field experiment was carried out as split-split plot in 2014 to assess the effects of four irrigation treatments (irrigations after 60, 80, 100 and 120 mm evaporation, respectively) on oil and protein changes of maize cultivars (SC704, NS640 and DC303: Late, mid and early maturing cultivars, respectively) at different seed positions on the ear (upper, middle and lower positions on the ear). Overall, the highest seed yield was obtained from SC704, followed by NS640 and DC303 cultivars. Seed yield of all cultivars was higher at lower seed position on ear than at middle and upper parts of the ear under different irrigation treatments. The highest oil and protein yields were also recorded for seeds at lower position on the ear. Seed yield of all maize cultivars at various seed positions decreased with increasing irrigation intervals. Oil percentage decreased, but protein percentage increased with decreasing water availability. Water limitation decreased oil and protein yields of maize cultivars. Changes in protein and oil yields of maize cultivars at different seed positions and irrigation treatments were attributed to changes in seed yield.

Accumulation of protein and starch in grain is a key process determining grain yield and quality in wheat. Under drought endogenous plant hormone levels will change and may have an impact on the yield and quality of wheat. In a greenhouse experiment, two winter wheat (Triticum aestivum L.) varieties differing in post anthesis drought resistance, tolerant (cv. Zagros) and sensitive (cv. Marvdasht), were subjected to either well-watered (WW) or water-stressed (WS) from anthesis to maturity. On the 7, 15 (grain enlargement stage) and 31 (grain filling stage) days after anthesis (DAA), endogenous abscisic acid (ABA) and indole-3-acetic acid (IAA) were determined in grain of wheat plants by enzyme linked immunosorbent assay (ELISA). The patterns of hormonal changes were similar in two varieties. The ABA levels were much higher under water deficit than well water treatment. In comparison grain ABA levels in all sampling stages was more in Marvdasht than Zagros. The endogenous grains IAA content display a marked reduction by the time and the water stress aggravated this reduction in both cultivars, however, the depresstion was more in drought-sensitive than drought-tolerant. The relationship between yields and contents of starch and protein in grains and levels of two hormones in sink organ indicated that the changes in yield and content of grain starch and protein under water withholding were associated with the reduced IAA and elevated ABA level in grains. It was proposed that the changed levels of endogenous hormones under drought post-anthesis might indirectly affect protein and starch accumulation in grains by influencing the regulatory enzymes and processes.

Plant growth regulators (PGR) have potential to increase grain yield and may also alter grain protein levels of cereal crops. A 3‐yr field experiment with spring barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) cultivars was conducted to determine whether ethephon treatment increased protein concentration, protein yield, and grain yield. A greenhouse experiment was also conducted to evaluate the response of barley grain protein concentration to gradual addition of ethephon (2.2 × 10‐3 mM) or chlormequat (5.8 × 10‐3 mM) solution after an thesis. Under field conditions, ethephon treatment increased barley and wheat grain protein concentrations by as much as 16 % but decreased grain yield so that protein yield increases were small or did not occur. For Laurier barley, total gram N content was increased by up to 20 % in one year of this study. However, over the 3 years, an inverse relation existed between grain protein and yield. Greenhouse data showed that i) the gradient in grain size and protein concentration among spikelets of a spike, which is established before anthesis, was not affected by either chlormequat or ethephon; and ii) chlormequat increased grain protein by 7 to 11 % whereas ethephon increased protein concentration by up to 13 % in one of the two experiments. Our data indicate that PGR can alter protein accumulation in the grain, and thus, the quality of bread wheat and feed barley crops can be increased m regions with a short crop‐growing season. However, a portion of the increase in gram protein concentration is due to decreased starch deposition, which is associated with yield reductions. The greenhouse data confirmed that a portion of the increase in grain protein concentration due to PGR application is caused by increased protein accumulation in the barley grain.

This study was conducted to examine the effect of five organic and mineral nitrogen fertilizer levels (F1 = 0, F2 = 17.5 kg organic nitrogen (ON) + 17.5 kg mineral nitrogen (MN), F3 = 35 kg MN, F4 = 35 kg ON + 35 kg MN and F5 = 70 kg MN / fed) on the growth characters, yield, its component and some chemical properties of three bread wheat cultivars (Sids 12, Gemmeiza 11 and Giza 168).The experimentwas carried out at two locations, the first location, at the Research and Experimental Centerof Faculty of Agriculture of Moshtohor,(Toukh Directorate, El-Kalubia Governorate) Benha University, Egypt, the second location, at the farm of Zarzora Agricultural Research Station, Etay El-Baroud Directorate, El-Behaira Governorate, Egypt, which planting in the same winter season 2014/2015. The obvious results of this investigation can be summarized as follows: Wheat cultivars were significantly differed in all traits studied in the two locations and the combinedaverage, except nitrogen use efficiency was not significant. Gemmeiza 11 cultivar significantly surpassed Sids 12 and Giza 168 cultivars in flag leaf area (cm2), plant height (cm), spike length (cm), spike weight (g), kernels weight/spike (g), 1000-kernel weight (g), biological yield (kg/fed), grain yield (kg/fed) and grain protein yield (kg/fed) as well as grain nitrogen uptake (kg/fed). While,Sids 12 recorded the highest values of No. of kernels/spike, harvest index (%), hectoliter weight (kg/hl), grain nitrogen content (%) and protein content in grain (%) also, Sids 12 cultivar was earlier heading and physiological maturity dates compared with Giza 168 and Gemmeiza 11. Meanwhile, Giza 168 surpassed the other two cultivars in No. of tillers/m2, No. of spike/m2 and straw yield (kg/fed). All characters under study showed significantly increased by increasing nitrogen fertilizer levels,except NUE significantly decreased with increasing N levels in Moshtohor location, Zarzora locationandthe combined analysis.Applied of 70 kg MN /fed recorded the highest values, also increasing nitrogen fertilizer levels delayed heading and physiological maturity dates. Planting Gemmeiza 11 which fertilized by 70 kg MN/fedrecorded significantly the highest values of flag leaf area, biological, grain and protein yields/fed as well as grain nitrogen uptake/fed(in the two locations and the combined analysis), plant height and weight of kernels/spike (in Moshtohor location only and the combined analysis). Meanwhile, Sids 12 under the same nitrogen fertilizer surpassed the other treatments in No. of kernels/spike (in Moshtohor location only and the combined analysis) and harvest index (in the two locations and the combined average). Whereas, Giza 168 with the same level of nitrogen fertilizer gave the highest No. of tillers/m2 (in Moshtohor location only and the combined analysis), No. of spike/m2 and straw yield/fed (in the two locations and the combined analysis). It could be summarized that sown wheat Gemmeiza 11 cultivar and application of 70 kg mineral nitrogen per fed or 35 kg organic N + 35 kg mineral nitrogen maximized grain yield per unit area.

The protein accumulation in wheat (Triticum aestivum L.) grains is seldom studied under dryland condition although it has been widely tested under irrigated conditions. For understanding the protein accumulation characteristics of wheat cultivars differing in drought tolerance and the effects of water and nitrogen, a drought-tolerant cultivar, Jinmai 47, and a drought-sensitive cultivar, Nongda 189, were planted under both irrigated and dryland conditions with three nitrogen application rates. From the 5th day after anthesis, spikelets and flag leaves were sampled at a 5 days interval for measuring the contents of protein and its com-ponents in grains and the enzymes activities in grains and flag leaves. The results indicated that the contents of albumin, gliadin, glutenin, total protein, and the ratio of glutenin to gliadin in dryland cropping were higher than those in irrigated cropping, but the globulin content was lower than that in irrigated cropping. For Nongda 189, the contents of protein and its components and the ratio of glutenin to gliadin in grains were affected significently by drought, whereas for Jinmai 47, the variations on contents of globulin, gliadin, total protein, and ratio of glutenin to gliadin were slightly. The activities of glutamine synthetase (GS), glutamate synthase (GOGAT), glutamic acid-pyruvate transaminase (GPT) in grains and the activities of GS and GOGAT in flag leaves were reduced in dryland cropping compared with those in irrigated cropping. Simultaneously, the trend of GPT activity in grains was also affected by dryland cropping. The effect of drought on activities of these enzymes that involved in protein accumulation was greater in Nongda 189 than in Jinmai 47. Nitrogen application promoted the contents of protein and its components in grains, and higher rate of nitrogen application resulted in greater positive effect. Jinmai 47 presented greater effect of nitrogen application on protein content in grains than Nongda 189. Under both growing conditions, the activities of GS, GOGAT, and GPT in grains and the activity of GOGAT in flag leaves in all nitrogen treatments significantly correlated with the protein yield rather than the pro-tein content in grains. The correlation between GS activity in flag leaves and protein yield in grains was different in the two cultivars. The above results suggest that the drought-tolerant cultivar is less affected by water condition compared with the drought-sensitive cultivar; application of nitrogen could promote the protein content in grains, and the effect is greater in the drought-tolerant cultivar than in the drought-sensitive cultivar.

To explore the physiological mechanisms of stresses on nitrogen metabolism and protein accumulation in wheat grains,a pot experiment was performed at the Scientific Educational Park of Henan Agricultural University from 2010 to2012. Zhengmai 366 and Yunong 949,wheat cultivars with different gluten-strengths,were grown in 24-cm pots with 10 kg loam soil for the experiment,which was performed using a completely randomized design in three replicates. Plants were initially grown in the field environment and were then transferred to a climate-controlled greenhouse for the high temperature( HT) treatment. HT began from the 8thday after anthesis( DAA) and ended at the 11 thDAA,with a high temperature of38°C for five hours from 11: 00 to 16: 00,after which the plants were returned to the field environment. The concentration of protein and its components,and the activities of glutamine synthetase( GS) and glutamic-pyruvic transaminase( GPT)in the grains were measured to evaluate the effects of the stresses. The results showed that HT,drought stress( DS) andtheir combination significantly increased protein and its components' concentrations,yet decreased the ratio of glutenin to gliadin. The protein accumulation was also reduced by stresses. For example,for Zhengmai 366,the protein yield significantly decreased by 20. 7% under HT,by 16. 2% under DS,and by 26. 1% under a combination of HT and DS. In Yunong 949,the protein yield decreased by 12. 4% under HT,by 11. 9% under DS and by 15. 8% under a combination of HT and DS. The grain weight significantly declined by 23. 2% under HT,by 18. 0% under DS and by 29. 9% under a combination of HT and DS,in Zhengmai 366,and decreased by 24. 0% under HT,by 16. 0% under DS,and by 29. 9%under a combination of HT and DS,in Yunong 949. However,the activities of GS and GPT were promoted under HT,DS and their combination. A correlation analysis showed that the activity of GS was positively correlated with the protein concentration in mature wheat grains at significant or extremely significant levels at 8,17,23,and 29 DAA. However,GS activity was negatively correlated with protein yield at extremely significant levels at 23 and 35 DAA,and it was negatively correlated with grain yield at significant or extremely significant levels at 8,17,23,29 and 35 DAA. The activity of GPT was positively correlated with protein concentration at extremely significant levels at 11 and 17 DAA. However,GPT activity was negatively correlated with protein yield at extremely significant levels at 8,17 and 23 DAA and negatively correlated with grain yield at significant or extremely significant levels at 8,11,17 and 23 DAA. The results also indicated that,under the present experimental conditions,the influence of the HT treatment was greater than that of the DS,and an overlap effect existed between HT and DS. In addition,Zhengmai 366,a high-gluten cultivar,showed more sensitivity to stresses than Yunong 949,a mid-gluten cultivar. These results may aid in understanding how HT and DS influence protein accumulation and may be useful in improving wheat quality.

Water productivity, yield response factors, yield and quality of alfalfa cultivars in semi-arid climate conditions

Two experiments was conducted during 2013-2014 growing season at the Research Field belong to College of Agriculture, Salahaddin University, Erbil, Kurdistan Region, Iraq in order to identify drought-tolerant cultivars of bread and durum wheat. The first experiment was conducted under rainfall (stress) conditions. The second experiment was conducted under rainfall and irrigation (non-stress) conditions. Ten bread wheat cultivars (Mexipak, Abu-graib 3, Adnania, Rabia, Ipa 99, Tammoz 2, Aras, Cham 4, Cham 6 and Adana 99) were planted on 15 Nov, 2013 using Randomized Complete Block Design with three replicates in each of experiment. The same two experiments were applied to ten cultivars of durum wheat (Senator Capelii, Cocrate- C 71, Om-Rabi 5, Wahat Al-Iraq, Coseim N, Cham 3, Acsad 65, Ofanto, LD 357 E and Simeto). Some drought tolerance indices were calculated for every cultivar using the corresponding non-stressed and stressed grain yield/plant in each replication. Results showed a significant reduction in grain yield for bread and durum wheat cultivars under stress conditions. Grain yield under rainfall (Ys) and irrigated (Yp) conditions was significantly and positively correlated with geometric mean productivity (GMP), harmonic mean (HM), mean productivity (MP), stress tolerance index (STI), modified stress tolerance index (K1STI, K2STI), and germination stress index (GSI) in bread wheat and with GMP, HM, MP, STI, yield index (YI), K1STI, K2STI, stress non stress production index (SNPI) and GSI in durum wheat revealed that these indices were more reliable to select high yielding bread and durum wheat cultivars under rainfall and irrigated conditions. Screening drought tolerant cultivars using mean rank, standard deviation of ranks and rank sum (RS) distinguished cultivars, Mexipak, Abu-graib 3, Rabia Tammoz 2 and senator capelii, Wahat Al-Iraq, Cham 3 and Acsad 65 exhibited low standard deviation of rank, with least RS was the most drought tolerant bread wheat and durum wheat cultivars, respectively. We can identify the cultivars with high and stable yield in both conditions which are (Mexipak [1], Abu-graib 3 [2] and (Senator Capelii [1], Coseim N [5], LD 357 E [9] in bread and durum wheat cultivars, respectively therefore, we can recommend these cultivars as superior cultivars for planting under conditions of drought stress. Cluster analysis showed that the bread and durum cultivars, based on indices tended to group into three groups: tolerant, semi-tolerant and sensitive cultivars.

Protein content and protein yield of three spring wheat cultivars differing in morphological and physiological growth characters were found to be influenced by intercultivar competition, irrigation levels and nitrogen fertilization. The protein content of the tall cultivar C 306 and the protein yield of the dwarf cultivar HD 2160 were more than the other cultivars. Binary mixed stands were not superior to the better component cultivar. Intercultivar competition increased the protein content of dwarf and semi-dwarf cultivars, but decreased the protein content of tall cultivar. On the other hand, protein yield of the dwarf cultivar decreased and that of tall cultivar increased when grown in mixed stands. Protein yield of semi-dwarf cultivar increased when grown with dwarf cultivar, but decreased when grown with tall cultivar. Two or three irrigations increased the protein content and protein yield of all the three cultivars and their mixed stands over one irrigation. Protein content and protein yield of the cultivars and their mixed stands were higher when 150 kg N/ha was applied than when 80 kg N/ha was applied.

The effect of six different zinc (Zn) application methods on grain yield and concentrations of Zn in whole shoots and grain was studied in wheat cultivars (Triticum aestivum, L. cvs. Gerek‐79, Dagdas‐94 and Bezostaja‐1 and Triticum durum, Desf. cv. Kunduru‐1149) grown on severely Zn‐deficient calcareous soils (DTPA‐extractable Zn: 0.12 mg‐kg‐1 soil) of Central Anatolia which is the major wheat growing area of Turkey. Zinc application methods tested were: a) control (no Zn application), b) soil, c) seed, d) leaf, e) soil+leaf, and f) seed+leaf applications. Irrespective of the method, application of Zn significantly increased grain yield in all cultivars. Compared to the control, increases in grain yield were about 260% with soil, soil+leaf, and seed+leaf, 204% with seed and 124% with leaf application of Zn. In a similar manner, biomass production (dry weight of above‐ground parts) was increased by Zn treatments. The highest increase (109%) was obtained with the soil application and the lowest increase (40%) with the leaf application. Significant effects of Zn application methods were also found on the yield components, i.e., spike number.m‐2, grain number‐spike‐1, and thousand kernel weight. Spike number.m‐2 was affected most by Zn applications, particularly by soil and soil+leaf applications. Concentrations of Zn in whole shoots and grain were greatly affected by different Zn treatments. In plants without added Zn, concentrations of Zn were about 10 mg‐kg‐1 both in shoots and grain and increased to 18 mg‐kg‐1 dry weight (DW) by soil application of Zn, but not affected by seed application of Zn. Soil+leaf application of Zn had the highest increase in concentration of Zn in shoot (82 mg‐kg‐1 DW) and grain (38 mg‐kg‐1 DW). Soil application of Zn was economical and had long‐term effects for enhancing grain yield of wheat grown on Zn deficient soils. When high grain yield and high Zn concentration in grains are desired, soil+leaf application of Zn was most effective method of Zn application.

Grain protein content is a major contributor to nutritional quality of wheat. Due to the negative relationship between yield and protein content, simultaneous improvement of these traits is very difficult. The aim of this study was to identify possible selection criteria to improve protein content and yield simultaneously. Six spring irrigated wheat cultivars were used as parent lines in a half diallel design. The F1 hybrid progeny and parents were used as experimental material. Both high and low protein wheat types translocated equal amounts of nitrogen to the grain. Phenotypic correlations re-emphasised the problems of simultaneous improvement of grain yield and protein content. The use of correlated response gave a better solution. If grain protein yield (highly significantly correlated with grain yield), was used as selection criterion, even protein per kemel showed a correlated response. It also had a relatively high narrow sense heritability. Grain protein yield selection therefore gave the only possible solution towards simultaneous improvement of grain yield, and grain protein content.

Deschampsia antarctica has managed to colonize the maritime Antarctic. One of the main factors associated with its tolerance to low temperatures is the presence of apoplastic proteins with antifreeze activity. This work focuses on the effect of cold acclimation of D. antarctica on the accumulation of apoplastic proteins with antifreeze activity. Antifreeze proteins present in apoplastic extracts were purified by ice affinity purification, and their identity was determined by protein sequencing. D. antarctica plants were subjected to 22 days of cold acclimation at 4 °C. The highest content of apoplastic proteins with antifreeze activity was obtained at between 12 and 16 days of acclimation. Protein sequencing allowed their identification with >95% probability. Percentage coverage was 74% with D. antarctica ice recrystallization inhibition protein 1 (DaIRIP1) and 55% with DaIRIP3. Cold acclimation of D. antarctica improved the yield of apoplastic proteins, and resulted in an increase in the antifreeze activity of apoplastic extracts. An in silico analysis suggested that the fluctuations presented by the three-dimensional structures of DaIRIPs help to explain the presence of certain DaIRIPs in apoplastic extracts under the cold acclimation conditions evaluated.