Exogenous glycinebetaine application improves yield under water-limited conditions in hybrid sunflower

Limited water availability is a severe threat to the sustainability of crop production. Exogenous application of glycinebetaine (GB) has been found very effective in reducing the adverse affects of water scarcity. This study was conducted to examine the role of exogenous GB application in improving the yield of hybrid sunflower (Helianthus annuus L.) under different irrigation regimes. There were three levels of irrigation: Control (four irrigations), three irrigations (irrigation missing at budding stage) and two irrigations (irrigation missing at budding and grain formation stage) in the experiment. While GB was applied exogenously at 100 mM GB each at budding and grain formation stages, the Control treatment did not receive any GB application. Data regarding yield, yield components and quality parameters showed that water stress reduced the head diameter, number of achene per head, 1000-achene weight and yield. Nonetheless, it was significantly improved by the exogenous GB application. Among the qualitative characteristics, protein contents were significantly increased by water stress at different growth stages but were reduced by exogenous GB application. Whilst oil contents were reduced by drought at different stages, GB application, however, did not ameliorate the negative effect of drought stress on achene oil contents. The effects of water stress and foliar application of GB were more pronounced when applied at vegetative stage than at the reproductive stage. Moreover, exogenous GB application was only advantageous under stress conditions.     

Boron-induced improvement in physiological,biochemical and growth attributes in sunflower (Helianthus annuus L.) exposed to terminal drought stress

Terminal drought stress (drought at reproductive growth stage) has been considered a severe environmental threat under changing climatic scenarios and undoubtedly inhibits sunflower production. A field study was conducted to explore the potential role of foliar applied boron (B) (0, 15, 30, 45 mg L^?1) at late growth periods of sunflower in alleviating the adversities of terminal drought stress (75, 64, 53 mm DI) grown from inflorescence emergence to maturity stages. The plant water relations such as leaf relative water content (RWC), water potential (Ψ_w), osmotic potential (Ψ_s), and turgor pressure (Ψ_p) were increased significantly with B foliar sprays while exposed to terminal drought stress. Foliar B application considerably improved the nitrogen and B concentrations in leaf and seed tissues, and also chlorophyll a and b pigments under terminal drought stress conditions. Drought-induced proline accumulation prevented the damages caused by drought stress, nevertheless, B foliar spray increased its contents. Compared to well-watered conditions, terminal drought stress substantially declined the growth performance in terms of reduced leaf area index (LAI), crop growth rate (CGR), net assimilation rate (NAR), and total dry matter (TDM) production; however, foliar B supply (30 mg L^?1) might be helpful for improving drought tolerance in sunflower with reduced growth losses.     

Effects of Urea Foliar Application on Grain Yield and Quality of Winter Wheat

The effects of urea foliar application rates at different growth stages of wheat on protein and yield of winter wheat were evaluated in a factorial experiment. Time of application and amounts of urea foliar application rates were the treatments. Urea was applied at four stages including tillering, jointing, anthesis, and grain filling, and urea foliar application rates were 22.5, 45, 67.5, and 90 kg ha^?1 (12.5, 25, 37.5, and 50% of total urea application). Our data demonstrated that urea application time had significant effects on grain weight, number of seeds per spike, plant height, and protein content. Furthermore, total dry weight, grain weight, harvest index, 1000-seed weight, plant height, and protein content were significantly affected by amounts of urea foliar application. The effects of time?×?rate of urea foliar application on grain yield, 1000-seed weight, and plant height were significant.     

磷和钾对巴基斯坦西北部向日葵生长、产量的交互效应

Potassium (K) and phosphorus (P) applications improve growth, increase yield and yield components of sunflower (Helianthus annuus L.) on K and P deficient soils in Northwest Pakistan. A field experiment was conducted using sunflower cv. Hysun-33 at the New Developmental Research Farm of KPK Agricultural University, Peshawar, Pakistan, during summer 2006. The experimental design was a randomized complete block in split plot arrangements, with six levels of K (0, 25, 50, 75, 100, and 125 kg K ha^-1) as main plots and four levels of P (0, 45, 90, and 135 kg P ha^-1) as sub-plots with three replications. Sunflower yield and yield components responded positively to K and P fertilization but the magnitude of response varied with the levels of K and P. Days to flowering and maturity, grains per head, 1000-grain weight, shelling percentage, and grain yield increased tremendously in the K and P-fertilized plots as compared to the control with no K and P applied. The combined application of 100 kg K and 45 kg P ha^-1 significantly increased yield components, grain yield, harvest index, and shelling percentage of sunflower, suggesting that 100 kg K ha^-1 in combination with 45 kg P ha^-1 could maximize productivity of sunflower planted after wheat on the K and P deficient soils in the study area.     

Alleviation of drought stress in winter wheat by late foliar application of zinc,boron, and manganese

In many regions, drought during flowering and grain‐filling inhibits micronutrient acquisition by roots resulting in yield losses and low micronutrient concentrations in cereal grains. A field and a greenhouse experiment were conducted to study the effect of foliar applications of zinc (Zn), boron (B), and manganese (Mn) at late growth stages of winter wheat (Triticum aestivum L.) grown with or without drought stress from booting to maturity. Foliar applications of Zn, B, and Mn did not affect grain yield in the absence of drought. However, under drought, foliar application of Zn and B in the field increased grain yield (15% and 19%, respectively) as well as raising grain Zn and B concentration, while Zn and Mn sprays in the greenhouse increased grain yield (13% and 10%, respectively), and also increased grain Zn and Mn concentrations. Furthermore, under drought stress both in the field and greenhouse experiment the rate of photosynthesis, pollen viability, number of fertile spikes, number of grains per spike, and particularly water‐use efficiency (WUE) were increased by late foliar application of micronutrients. These results indicate that by increasing WUE foliar application of Zn, B, and Mn at booting to anthesis can reduce the harmful effects of drought stress that often occur during the late stages of winter wheat production. These findings therefore are of high relevance for farmers' practice, the extension service, and fertilizer industry.     

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.     

Growth and photosynthesis of salt‐stressed sunflower (Helianthus annuus) plants as affected by foliar‐applied different potassium salts

In order to assess the effectiveness of foliar‐applied potassium (K⁺, 1.25%) using different salts (KCl, KOH, K₂CO₃, KNO₃, KH₂PO₄, and K₂SO₄) in ameliorating the inhibitory effect of salt stress on sunflower plants, a greenhouse experiment was conducted. Sodium chloride (150 mM) was applied through the rooting medium to 18 d–old plants and after 1 week of salt treatment; different K⁺‐containing salts were applied twice in 1‐week interval as a foliar spray. Salt stress adversely affected the growth, yield components, gas exchange, and water relations, and also caused nutrient imbalance in sunflower plants. However, foliar‐applied different sources of potassium improved shoot and root fresh and shoot dry weights, achene yield, 100‐achene weight, photosynthetic rate, transpiration rate, stomatal conductance, water‐use efficiency, relative water content, and leaf and root K⁺ concentrations of sunflower plants grown under saline conditions. Under nonsaline conditions, improvement in shoot fresh weight, achene yield, 100‐achene weight, photosynthetic and transpiration rates, and root Na⁺ concentration was observed due to foliar‐applied different K sources. Of the different salts, K₂SO₄, KH₂PO₄, KNO₃, and K₂CO₃ were more effective than KCl and KOH in improving growth and some key physiological processes of sunflower plants.     

Foliar application of silicon at different growth stages alters growth and yield of selected wheat cultivars

To evaluate the response of some selected wheat cultivars to silicon application at different growth stages under drought stress, an experiment was carried out in the greenhouse of College of Agriculture, Shiraz University, Iran, during 2012 using a completely randomized factorial design with four replications. Experimental treatments included drought stress (100% F.C. as control and 40% F.C. as drought) and foliar application of 6 mM sodium silicate (control, application at mid tillering stage, at anthesis stage, and application at tillering + anthesis stages) and wheat cultivars (Sirvan and Chamran, relatively drought-tolerant, and Shiraz and Marvdasht, drought-sensitive cultivars). Drought stress significantly reduced chlorophyll content, leaf area, relative water content, grains per spike, 1000-grain weight, grain yield and biomass of all wheat cultivars. Furthermore, drought stress increased electrolyte leakage of the flag leaves of all cultivars. In contrast, foliar-applied silicon significantly increased these parameters and reduced electrolyte leakage. Furthermore, highest positive influence of silicon application was observed at combined use of silicon both at the tillering + anthesis stages in wheat plants under both stress and non-stress conditions. Significant differences were found in physiological responses among wheat cultivars. The drought tolerant cultivars (Sirvan and Chamran) had significantly higher growth and yield than those of drought sensitive cvs. Shiraz and Marvdasht under drought stress. In conclusion, foliar application of silicon especially at the tillering + anthesis stages was very effective in promoting resistance in wheat plants to drought conditions by maintaining cellular membrane integrity and relative water content, and increasing chlorophyll content.     

Effect of rhizobacteria and cytokinins application on wheat growth and yield under normal vs drought conditions

ABSTRACT

Drought is a major constraint for agricultural productivity worldwide, and it is likely to further increase. Different strategies are required to mitigate drought stress in plants. In a two-year study that conducted at agronomic research area of the Islamia University of Bahawalpur, we investigated the role of rhizobacteria (RB) and cytokinins (Ck) on drought tolerance, nutrient uptake, yield, and physiological parameters in wheat under drought stress at different developmental stages (tillering, anthesis, and grain filling). Thirteen treatments used were well-watered control plants without RB or Ck, drought at tillering, anthesis, or grain filling without or with RB alone, Ck alone, or combination of both (RB+Ck). In both years, and at the different stages, measured parameters were highest in the well-watered plants but lowest in drought-stressed plants. Application of RB and Ck to drought-stressed plants increased these parameters in the order RB+Ck > RB > Ck. In some cases, under drought stress, there was no difference between inoculation with RB and application of Ck. It was concluded that the combined application of RB and Ck could play a significant role in improving wheat yield and also alleviation of stress under drought condition.     

不同品种油葵对盐胁迫响应研究

通过盆栽试验,研究了盐胁迫对不同品种油葵出苗、生长、产量及植株Na+和K+吸收的影响,明确不同品种油葵对盐胁迫效应的差异。结果表明,随土壤盐浓度的升高,油葵的出苗率、株高、产量和生物量均有所下降,新葵杂6号受到的抑制作用更加明显;与全生育期的相比,各品种在出苗阶段的耐盐性远高于成苗至成熟期阶段,低盐胁迫对油葵的出苗和后期生长均有一定的促进作用。研究发现当盐胁迫对油葵苗期生长的相对抑制率超过40%时不能完成其生活史,超过50%时则不能生长至成熟期,在显蕾或花期枯死。随着盐胁迫程度的加剧植株中Na+的含量成倍增加,K+/Na+显著降低,而K+含量变化较小,适宜的盐浓度可促进植株对钾的吸收,但品种间存在较大的差异,在同一盐浓度下油葵植株中Na+含量陇葵杂1号<法A15<新葵杂6号,而K+含量与K+/Na+则刚好相反,各品种对盐胁迫的敏感性均为花期、显蕾期>苗期>成熟期;减少植株对Na+的吸收,维持K+的稳定性,保持较高K+/Na+是品种耐盐的重要机制之一,三个油葵品种中,陇葵杂1号耐盐性最强,其次为法A15,新葵杂6号耐盐性较差。     

Effects of potassium supply on growth and yield of safflower as compared to sunflower§

Safflower may have a certain production potential under German conditions, particularly in organic farming where the putatively low nutrient requirement is highly welcomed. However, current knowledge regarding the nutrient requirements of safflower as compared to similar oil crops is limited. It was thus the aim of this study to determine the growth and yield response of safflower (Carthamus tinctorius L.) as compared to sunflower (Helianthus annuus L.) with respect to potassium (K) supply. Three safflower and two sunflower plants were cultivated in 5 L Mitscherlich pots. Both species responded strongly to increasing K supply with respect to plant growth and yield. Growth and yield of safflower increased up to 1 g K per pot, while the optimum for sunflower was 3.0 g K per pot. Safflower out‐yielded sunflower at low K supply, while at high K level, the opposite was observed. Supply of K affected virtually all yield components in both species, though to different degree. The number of capitula in safflower was only slightly affected, and the number of achenes per capitulum was only reduced under severe K deficiency, while single‐achene mass increased with increasing K supply. In sunflower, the number of achenes per capitulum strongly responded to the K supply, as did the single‐achene mass. Oil yield in safflower was affected by K deficiency mainly due to reduced achene yield, not oil concentration. However, oil yield in sunflower was severely affected by low K supply due to both reduced achene yield and lowered oil concentration. Multiple‐regression analyses indicate that in sunflower, the stem dry matter (DM) and the total amount of K accumulated in the aboveground biomass were most important, while in safflower the total amount of K and N accumulated had the highest impact. It is concluded that sunflower is more sensitive to inadequate K supply than safflower.     

Response of sunflower hybrids to nitrogen application grown under different agro-environments

A wide gap exists between production and consumption of vegetable oils in Pakistan. Thereby, a significant proportion (2.28 million tons) of vegetable oils is being imported at the cost of 2257 million US$. Therefore, the present study was conducted to quantify the comparative performance of various sunflower hybrids as influenced by various levels of nitrogen (N) fertilizer under different agro-environments. The experimental treatments consisted of three sunflower hybrids (Hysun33, Hysun38, and Pioneer-64A93) and five levels of N fertilizer (0, 60, 120, 180, 240 kg N ha^?1), arranged in a randomized complete block design in a split plot with four replications. The field trials were conducted for two consecutive crop seasons under three different agro-ecologies (arid, semi-arid, and sub-humid) in the province of Punjab, Pakistan. The results of the study demonstrated that the productivity of sunflower hybrids varied greatly in response to N fertilization and different ecologies. Maximum achene yield of 3177 kg ha^?1 was harvested under sub-humid environment, followed by the semi-arid one. Among the hybrids, Hysun38 excelled the other two hybrids with a production of 3083 kg ha^?1 and 41% oil contents. Generally, the productivity of hybrids increased with the increasing doses of N fertilizer. Maximum achene yield was obtained by addition of 180 kg N ha^?1. The findings of the study revealed that yield potential of Hysun-38 could be exploited by addition of N fertilizer at the rate of 180 kg N ha^?1 under sub-humid environment.     

Evaluation of chitosan nanoparticles effects with two application methods on wheat under drought stress

Chitosan and its components have beneficial effects on a wide variety of plant species. Yet, their effects on wheat plants under drought stress are not well known. So, a field experiment was laid out in order to evaluate the effect of chitosan nanoparticles (NPs) on wheat. The wheat seeds were sown in plots. Then, the chitosan NPs were added to them through soil and foliar application at tillering, stem elongation, and heading stages. Results indicated that the drought stress significantly decreased majority of the studied traits compared to the normal irrigation. Application of the NPs especially 90?ppm increased leaf area (LA), relative water content (RWC), chlorophyll content, photosynthesis rate, catalase (CAT), and superoxide dismutase (SOD) activities, yield, and biomass compared to the control. Finally, our results highlight that usage of the chitosan NPs especially 90?ppm can mitigate adverse effects of drought in the wheat under drought stress.     

Tolerant varieties and exogenous application of nutrients can effectively manage drought stress in rice

ABSTRACT

Common abiotic stresses in rain-fed rice areas like drought can occur at any phase of crop growth and may occur periodically. Variation in intensity and severity of drought requires the use of different rice varieties and different nutrient management strategies. This study evaluated the morphological and physiological response of contrasting rice cultivars (Rajalaxmi, IR64, and Sahbhagidhan) to various nutrient combinations under water sufficience and scarce conditions. Drought stress at vegetative stage significantly reduced tiller formation, dry matter remobilization, and photosynthesis, leading to around 41.6% yield reduction. The effect of drought stress was more evident in Rajalaxmi and IR64 by a yield reduction of 57.4% and 43.2% as against only 24.3% in Sahbhagidhan. The combined application of nutrients resulted in higher proline accumulation, chlorophyll and carbohydrate concentrations, and photosynthesis and antioxidant enzymes, ultimately better tolerance to drought. This is reflected in higher values of tolerance indices and low scores of leaf drying and leaf rolling, especially for Sahbhagidhan. The combined application of P, K, Ca, Zn, and Fe resulted in 52.9, 53.3, 48.9% higher yield over P or K application. Rice drought tolerance can be managed by combining breeding of drought-tolerant high yielding varieties with the proper application of fertilizer nutrients.     

Inducing drought tolerance in wheat by applying natural and synthetic plant growth promoters

Crop productivity in future may be limited due to water scarcity. However, foliar spray of plant growth promoters may boost crop production even in adverse environments. In the present study, foliar application of one natural (moringa leaf extract, 3% MLE) and four synthetic (Polydol, Multisol, Classic, and Asahi Star) were applied at tillering, jointing, booting, and heading growth stages of wheat (Triticum aestivum L.) during severe, moderate, and light drought and well‐watered condition. No spray and water spray were taken as controls. Results showed significant reduction in growth parameters such as total dry matter production, mean crop growth rate, net assimilation rate, leaf area index, and duration due to drought employed at various phenophases of wheat. However, improvement in these parameters was observed after foliar application of growth promoters, whereas interactive effects between factors were found non‐significant. The activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) were more accelerated under drought treatments from exogenously supplied growth promoters. Foliar application of promoters significantly alleviated drought‐induced reduction of yield and related traits. Grain weight (15%) and grain yield (27%) were improved due to exogenously applied MLE under moderate drought stress treatments relative to controls. Furthermore, 16% higher grain yield and 17% saving of irrigation water over fully irrigated and without promoter treatment (farmers' practice) was recorded from foliar‐applied MLE under skipped irrigation at jointing. In conclusion, foliar‐applied MLE may ameliorate drought‐induced deleterious effects by enhancing antioxidant activities under drought stress.     

Nitrogen Sources and Rates Effect on Yield,Nutritional Status,and Yield Components of Sunflower

Due to the high levels of crude protein in the achene, sunflower (Helianthus annuus L.) is one of the main oilseeds grown worldwide, particularly for the oil and meal production for animal feed. Despite these advantages, there are few studies on nutrient use efficiency under tropical conditions, especially nitrogen (N). The experiment was conducted in greenhouse conditions to evaluate the effects of N sources and rates on sunflower achene yield (AY), yield and physiological components, and nutritional status of sunflower. The five N sources (calcium nitrate (Ca(NO₃)₂), potassium nitrate (KNO₃), ammonium nitrate (NO₃NH₄), ammonium sulfate ((NH₄)₂SO₄), and urea (CO(NH₂)₂)), and four N rates (0, 50, 100, and 200 mg kg^?1) were studied. AY was reduced with the ammonia sources application from the 100 mg N kg^?1. Plant height and capitulum dry weight (CDW), capitulum diameter, shoot dry weight (SDW), and chlorophyll content were significantly related with N sources and rates. Except for potassium (K), the N rates changed the N, P, Ca, Mg, and S concentration in the leaves and N concentration in achene. In the comparison of sources, on the average of N rates, urea application was more effective than the other N fertilizers in the AY.     

Combined Application of Potassium and Zinc Improves Water Relations,Stay Green,Irrigation Water Use Efficiency,and Grain Quality of Maize under Drought Stress

Abstract

Maize (Zea mays L.) plays an important role in the global food security, but its production is threatened by climate change, especially drought stress. Potassium (K) and zinc (Zn) are considered useful to mitigate the negative consequences of drought stress in plants. Therefore, the objective of this two-year study was to identify the best combination of K and Zn application to improve the water relations, photosynthetic pigments, yield, irrigation water use efficiency (IWUE) and grain quality of maize sown under mild and severe drought stress conditions. The consisted of three drought stress levels viz. 1) well-watered as control (WW), 2) mild drought (MD) with 25?mm of potential soil moisture deficit (PSMD), 3) severe drought (SD) with 50?mm of PSMD and six K-Zn treatments: i.e. 125, 100 and 150?kg ha^?1 K with 0 and 12?kg ha^?1 Zn. The results indicated that K-Zn application improved the water relations and chlorophyll contents, biological yield and grain quality, irrespective of water stress treatment. The combined application of K-Zn under mild drought stress produced statistically same biological yield and grain quality as under well-irrigated without K-Zn fertilization and also produced compratively higher IWUE, biological yield and grain quality under sverer drought stress. Hence, the application of K at 150?kg ha^?1 in combination with Zn at 12?kg ha^?1 might be useful to improve the maize production and grain quality under drought stress. As IWUE was low in WW conditions, therefore, irrigation scheduling must be re-evaluated for optimum water use efficiency.     

Effects of foliar selenium application on some physiological and phytochemical parameters of Vitis vinifera L. cv. Sultana under salt stress

Abstract

In this research the effect of foliar application of selenium (Se) at four levels (Na₂OSe₄; 0, 5, 10 and 20?mg L^?1) was evaluated on some phytochemical characteristics of Sultana grapevine under different salinity levels (NaCl; 0 or 75?mM). The vines were fed twice a week with Hoagland nutrient solution and Se was foliar applied twice with 24 intervals. During growing period, plant height, leaf number and leaf area were recorded. Moreover, at the end of experiment, mature leaves from middle nods of canes were used for measurement of some phytochemical indices. According to results, Se application had a positive effect on plant height, leaf numbers, leaf area and photosynthetic pigments content especially at 5?mg L^?1 and to some extent 10?mg L^?1 Se levels. Under salinity stress, foliar application of Se at 5?mg L^?1 considerably decreased vines leaves electrolyte leakage and lipid peroxidation values compared to non se-treated plants under salinity stress condition. Selenium had an additive effect on salinity stress (75?mM NaCl) induced accumulation of total phenol, total flavonoid, soluble sugars and proline content in leave of vines. Moreover, the interaction of salinity and Se at 5 and 10?mg L^?1 improved leaves antioxidant enzymes activities in Sultana grapevine. Likewise, foliar application of Se improved leaf mineral content in 75?mM NaCl -treated vines. Totally, foliar application of selenium (Se at 5 or 10?mg L^?1) increased salt tolerance through improvement in nutritional balance and by enzymatic and non-enzymatic antioxidant capacity in grapevine leaves.     

Genetic properties of drought tolerance indices in sunflower

Abstract

The objective of the present study was genetic analysis of yield-based drought tolerance indices using the diallel method. Twenty-one genotypes of sunflower (Helianthus annuus L.) derived from a half diallel cross between six inbred lines were evaluated in both stress and non-stress conditions using a randomized complete block design for each one. Eight drought tolerance indices comprising stress tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM), stress susceptibility index (SSI), tolerance index (TOL), yield index (YI) and yield stability index (YSI) were calculated based on grain yield under stress and non-stress environments. Significant genotypic differences were observed in TOL, GMP, MPSTI, HM and YI. Diallel analyses revealed the importance of both additive and non-additive gene effects in GMP, STI, HM and YI. However, the Baker ratio supported the predominance of an additive effect in their expression. Our results demonstrated that SSI, YSI, TOL and MP are not reliable indices to select drought tolerant genotypes in sunflower breeding programmes because of their low heritability. Indices such as GMP, STI, HM and YI were moderately heritable and are usually able to select high-yielding genotypes in both environments and could be usefully employed in drought tolerance breeding programmes of sunflower.     

Foliar application of iron,zinc, and manganese nano-chelates improves physiological indicators and soybean yield under water deficit stress

Abstract

To investigate the effect of foliar application of nano-chelates of iron, zinc, and manganese subjected to different irrigation conditions on physiological traits, and yield of soybean (cultivar M9), a split plot experiment was conducted in a completely randomized block design with three replications in two crop years (2016–2017). The main plot included four levels of irrigation (I): full irrigation (I ₁), irrigation withhold at flowering stage (I ₂), irrigation withhold at podding stage (I ₃), and irrigation withhold during the grain filling period (I ₄). Also, the subplot included eight levels of foliar application with Fe, Zn, Mn, Fe?+?Zn, Fe?+?Mn, Zn?+?Mn, Fe?+?Zn?+?Mn nano-chelates, and distilled water (control). The results of combined analysis of variance suggested that the effect of irrigation and foliar application of nano-chelate was significant on all traits. Water deficit stress significantly reduced the grain yield. The minimum numbers of pods per plant, number of grains per plant, 100-seed weight per plant, leaf area index, leaf chlorophyll concentration, total dry weight of plant, and the grain yield were obtained by irrigation withhold at podding stage. Foliar application of combined nano-chelates increased the soybean resistance against water shortage more considerably than the separate consumption of these elements. Under drought stress in podding stage, the application of Fe?+?Zn led to the highest yield with a mean of 2613.84?kg ha^?1 where this increase was 61.1% higher than control.