Unraveling Wheat Grain Quality,Physiological Indices,Dry Matter Accumulation,and Attenuating Water Stress Adverse Effect Via Foliar Potassium Application at Different Growth Stages

Water resources are increasingly scarce, and in drought prone production systems, the capability of the plant to recover its adverse effects is important for yield stability. There is an urgent need to develop water-saving strategies for wheat production. Water stress at critical growth stages diminishes wheat production and has harmful effects on crop growth and development; however, regulated water deficit and potassium foliar application ameliorates its adverse effect up to a certain extent. Consequently, the water deficit effect at different growth stages of the crop with exogenous application of potassium was evaluated in a screenhouse experiment in a complete randomized design (CRD) having four repeats. Varieties of wheat, i.e. Lalma (drought resistant) and Pakhtunkhwa-2015 (drought susceptible), were sown. Water deficit, i.e. mild water stress (50% of water required for field capacity) and severe stress (no application of water), at different growth stages of the crop were imposed. Potassium (K) foliar spray (1%) from potassium sulfate (K₂SO₄) was applied at the respective stage subjected to water deficit levels. Internal water status, i.e. relative water content (RWC) and water retention capacity (WRC), were attained maximum at tillering stage under mild stress than the rest of the stages with maximum for Lalma. Conversely, water saturation deficit (WSD) and water uptake capacity (WUC) were higher under severe stress imposed at grain filling stage. Theses indices were maintained by foliar potassium application. Similarly, dry matter (DM) allocation varied for stress level imposition and translocation to other parts were improved under foliar K application. The chlorophyll indices, i.e., soil plant analysis development (SPAD) value, also decreased with the severity of water deficit. Grain yield was higher under stress imposition at grain filling stage than the rest of the stages, though severe water stress decreased yield significantly. The Potassium (K) foliar spray showed no prominent effect at grain filling. Canopy temperature increased with stress severity and was maintained under K foliar spray. Osmotic adjustment, water and turgor potential were affected by water stress and maintained with foliar K spray. Grain quality and biochemical traits of wheat were affected severely under water deficit. Potassium foliar spray was found to decrease the adverse effect of the water stress and hence maintained the quality and biochemical characters. It is concluded that application of foliar potassium decreases the adverse effects of water stress at any growth stage, minimises the stress indices drastic effect and maintains the internal water balance of the crop at different stages subjected to water deficit.

     

Effects of Deficit Irrigation and Fertilization on Quinoa (Chenopodium quinoa Willd.) Water Status and Yield Productions

Worldwide population is in permanent growth, leading to an over-presser on the food resources. This demand leads to an over-exploitation of land and water resources. Recently, the quinoa plant has attracted attention as alternative crop with high nutritive value and high tolerance to the marginal conditions. In this study, a field experiment was conducted during two successive seasons to investigate the effect of deficit irrigation on the agronomic performance. Four treatments of deficit irrigation (100%, 50%, 33% ETc and rainfed) were applied to one variety in the first season and to four genotypes (two varieties and two lines). The results were evaluated by measuring biomass and seed quinoa yield, water-use efficiency, harvest index, seed size and 1000 seeds weight. Results show that the implementation of deficit irrigation is an appropriate strategy to reduce the use of agricultural water and maintain relatively high yields. On the other hand, the results of the economic quality reflected by the size and weight of seed yield, indicates that quinoa can be considered a well-adapted to the conditions of water scarcity culture. According to agronomic parameters, L143 line followed by the line L11 showed a high potential of adaptation under the different treatments of stress, while the “Puno” variety presented the best performance under the favorable conditions of irrigation (100% ETc).

     

Allelopathic Potential of Soliva sessilis Ruiz & Pav. on Wheat

Soliva sessilis (Burweed) is a winter annual weed found in wheat crop of Pakistan. It is thought to have an allelopathic effect on wheat crop. In this regard, an experiment was conducted in 2019 in the department of Weed Science and Botany at the University of Agriculture Peshawar, to assess the allelopathic potential of S. sessilis on various wheat varieties grown in Peshawar, Pakistan. Physiologically matured roots and leaves of S. sessilis were dried, ground and stored. Three common wheat varieties were selected for the research including Atta Habib, Pirsabaq-15, and Shahkar-13. The treatments of the experiment comprised of the aqueous extracts of the roots and leaves of S. sessilis, hot water extracts, methanol extracts, litter, and mulches. A mass of 5?g of S. sessilis was taken for the different extracts for 24?h, however, the methanol extract was kept for 48?h. The effect of the treatments was highly significant on wheat seed germination, radicle length, plumule length, fresh biomass as well as dry biomasses of the three tested wheat varieties. The variety Atta Habib was discovered as the most susceptible variety to the treatments of aqueous extracts, hot water extracts, and leaves’ litter. In contrary, the variety Pirsabaq-15 exhibited a remarkable increase in the various data collection parameters. The leaves of S. sessilis were observed more toxic as compared to the roots. The mulch of S. sessilis indicated stimulatory effect on the wheat varieties. For the interaction effect between treatments and varieties, the leaves and roots aqueous extract and their litter showed inhibitory effect. In conclusion, the leaves and roots of S. sessilis are potentiality allelopathic to wheat crop plants and further study is needed to assess the types of these allelochemicals present in the leaves and roots of the weed.

     

Effects of Sowing Dates and Seeding Rates on Nitrogen and Water Use Efficiency of Facultative Wheat

In this study, effects of different sowing dates and seeding rates on N uptake efficiency (NUE), N translocation efficiency (NTE), agronomic efficiency (AE), physiological efficiency (PE), water use efficiency for grain yield (WUE_g) and water use efficiency for biomass (WUE_b) of facultative wheat were investigated. As the average of cropping year, sowing dates and seeding rates, N uptake efficiency (NUE), N translocation efficiency (NTE), agronomic efficiency (AE), physiological efficiency (PE), water use efficiency for grain yield (WUE_g) and water use efficiency for biomass (WUE_b) values were respectively obtained as 1.17?kg N_uptake/kg N_applied, 68.5%, 36.9?kg grain/kg N_applied, 31.2?kg grain/kg N_uptake, 5.19?kg ha^?1 mm^?1 and 18.04?kg ha^?1 mm^?1.

Nitrogen and water use efficiencies decreased with delayed sowing dates and increased with increasing seeding rates. It is possible to maintain a high wheat yield, nitrogen and water use efficiency by increasing plant density through winter sowing. It was concluded based on present findings that sowing date and seeding rates had significant effects on nitrogen and water use efficiencies and winter sowing should be practiced as not to cause yield losses and high seeding rates (575 seeds m^?2) yielded greater nitrogen-water use efficiencies.

     

Effects of Irrigation Water Salinity and Water Depth On Growth and Yield Parameters of NERICA Rice (Oryza sativa L. × Oryza glaberrima L.)

NERICA rice was developed through the hybridization of Oryza Glaberrima and Oryza sativa in an attempt to produce a higher yield in areas with a limited water supply. This study investigated the interactive effects of irrigation water salinities (0.38, 1.5, 3.0, 5.0, 7.0, 10.0 and 15?dSm^?1) for various water depths (5, 10 and 15?cm) on crop yield and related components of NERICA rice variety. This study showed that increased levels of irrigation water salinity resulted in reduced rice yield, biomass weight, plant height, harvest index, 1000 grain weight, evapotranspiration, water use efficiency, stomatal conductance, and chlorophyll content, and increased plant sterility for all irrigation water depths. The threshold values of soil salinity for the NERICA rice for the 5, 10, and 15?cm depths were 2.14, 81 2.80, and 1.98 dSm^?1, respectively. The study showed that the optimum salinity/water depth condition for the production of transplanted NERICA rice is irrigation water salinity <?1.50 dSm^?1, and a 10?cm water depth. This irrigation water salinity level maintains the soil ECe at or below the salinity threshold value of 2.80 dSm^?1. This study showed that NERICA rice has a salinity threshold value of 2.80 dSm^?1. Since rice is generally considered to be more salt-sensitive during germination, it is recommended that farmers apply the least saline water available during the rice germination stage of growth. Information from this study will assist policymakers and farmers to better manage NERICA production in Sub-Saharan Africa.

     

Characterization of Drought Tolerance in Bread Wheat Genotypes Using Physiological Indices

Wheat (Triticum aestivum L.) is a staple food in many countries and is regarded as a vital source of nutrition. Drought is one the most prevalent limitations to wheat growth and development. Herein a two year study was conducted using 25 diverse wheat genotypes obtained from the gene pool of various research institutes of Pakistan to characterize their drought tolerance using various physiological indices like relative water content (RWC), relative dry weight (RDW), water saturation deficit (WSD), relative water loss (RWL), flag leaf area (LA), chlorophyll content index (CC) and their association with the grain yield (GY). Analysis of variance (ANOVA) indicated the presence of significant amount of differences and genetic diversity among genotypes under study. Correlation analysis exposed positive association of CC and LA with GY. However, RWC was shown to have a highly significant and negative association with WSD and RWL. Principal component analysis (PCA) showed that out of the 7 PCs only 2 were significant having eigenvalues >?1; cumulatively accounting for 88.70% and 73.03% of the total variation under control and drought stress conditions, respectively. Strikingly the results of the PCA biplots and cluster heat map exposed G1 (Barani-17), G2 (Dharabi-11), G3 (Ehsan-16), G4 (Chakwal-50), G17 (Ujala-2016) and G23 (Kohistan-97) as potential drought tolerant genotypes. Selection of the positively associated indices would be fruitful and the tolerant genotypes having drought tolerance potential could be utilized in future wheat breeding programs to develop high yielding and drought tolerant genotypes.

     

Ascorbic Acid Enhances Growth and Yield of Sweet Peppers (Capsicum annum) by Mitigating Salinity Stress

Salinity is a crucial problem which has affected crop productivity globally. Ascorbic acid is considered helpful against abiotic stresses due to its powerful antioxidant potential. In the pot experiment, salinity stress (0, 35, 70, and 105?mM) was applied to sweet peppers in split doses after 20 days of transplantation. To mitigate the adverse effects of salinity, ascorbic acid (0, 0.40, 0.80, and 1.20?mM) was applied as foliar spray after a 6-day interval during vegetative growth. Sweet pepper plants sprayed with distilled water (control) recorded maximum plant height (cm), leaf area (cm²), number of branches, stem diameter (mm), number of fruit plant^?1, fruit diameter (cm), yield plant^?1 (g), and chlorophyll content (mg 100?g^?1), while the maximum polyphenol oxidase (PPO) activity (unit mg protein^?1 min^?1) and ascorbate peroxidase (APX) activity (unit mg protein^?1 min^?1) were recorded in plants treated with 70?mM NaCl application. Salinity stress beyond 70?mM significantly reduced all the studied parameters. An ascorbic acid concentration of 1.20?mM significantly mitigated the negative effects of salt stress and recorded maximum plant height (cm), number of leaves plant^?1, leaf area (cm²), number of branches plant^?1, stem diameter (mm), number of fruit plant^?1, fruit diameter (cm), yield plant^?1 (g), chlorophyll content (mg 100?g^?1), PPO activity (unit mg protein^?1 min^?1), and APX activity (unit mg protein^?1 min^?1). Hence, a 1.20?mM concentration of foliar ascorbic acid could be used in saline conditions up to 70?mM of sodium chloride (NaCl) for better growth, productivity, and enzymatic activity of sweet peppers.

     

Flower Quality in Roses (Rosa Hybrida) Sprayed with Ascorbic Acid

Colombia is a country recognized for its variety of fresh flowers for export, among which roses represent a significant quantity. However, cut flowers must meet some quality requirements imposed by the international market. Ascorbic acid in living organisms has an extensive function as a free radical scavenger; therefore, it reduces the negative effects of oxidative stress. It is also involved in the biosynthesis of several hormones, has many functions in chloroplasts, and is a fundamental compound for the correct functioning of the photosynthetic apparatus. The exogenous application of ascorbic acid improves the quality and nutritional value of agricultural products and induces stress resistance in plants. A greenhouse study was carried out in Cota, Colombia, with the objective of improving the quality of rose flowers by spraying ascorbic acid in concentrations of 0.0 (control), 600, and 1200?mg?L^?1 in the Escimo, Latin Beauty, and Freedom cultivars. In response to the spraying, an increase in stem length and stem thickness was observed in all cultivars which was directly proportional to the concentration of ascorbic acid applied. There was no clear trend found in the response of cultivars to ascorbate regarding head size and chlorophyll content (SPAD) since in some cultivars, the values of these variables increased or decreased with statistically significant differences. As a result, spraying with ascorbic acid significantly improves some components of the quality of rose cut flowers, even though the response is highly dependent on the cultivar.

     

Application of Trichoderma harzianum Strain KABOFT4 for Management of Tomato Bacterial Wilt Under Greenhouse Conditions

Clavibacter michiganensis subsp. michiganensis is a very important pathogen that causes bacterial wilt of tomato (BWT). Biological control of plant diseases is a critical tool for protecting the environment from chemical pollution. Twenty-five isolates of the genus Trichoderma were obtained from a healthy tomato root. Of the 25 isolates, KABOFT4 showed highly antagonistic activity that controlled the growth of C. michiganensis subsp. michiganensis (Cmm7) under in vitro conditions. The 5.8S ribosomal RNA gene and internal transcribed spacer identified the isolate as Trichoderma harzianum KABOFT4. The effect of this isolate as a soil drench and/or foliar application on bacterial wilt under greenhouse conditions was studied. The germination percentage of tomato seed treated with KABOFT4 increased by 36.7% compared to infected seed treated with only the pathogen Cmm7. Under greenhouse conditions, tomato seedlings treated with KABOFT4 as a soil drench, foliar and soil treatment, and foliar treatment had a 61.3, 26.7, and 40% reduced disease severity relative to the infected control, respectively. All treatments had a positive effect on tomato plants that presented as greater vegetative growth and accumulation of dry matter. The best fresh and dry weight was recorded when plants were treated with KABOFT4 as a soil and foliar application. Tomato plants treated with KABOFT4 also had increased total phenol and flavonoid contents in inoculated and non-inoculated plants compared to untreated plants. Under greenhouse conditions, T. harzianum strains can be used as an environmentally friendly way to manage the most economically important tomato disease. The results showed that a native endophytic strain of T. harzianum was a potent biocontrol agent against C. michiganensis subsp. michiganensis. Application of this strain to tomatoes in the greenhouse resulted in a decrease in disease severity and an increase in crop biomass.

     

Effects of mulches on water use in a winter wheat/summer maize rotation system in Loess Plateau,China

Limited water resources often result in reduced crop yield and low water productivity(WP). In northwestern China, crop production is generally dependent on precipitation. Therefore, a variety of agricultural rainwater harvesting(ARH) techniques have been used for conserving soil moisture, ameliorating soil environment, increasing crop yield, and improving water use efficiency. A two-year(2013–2015) field experiment was conducted under a typical sub-humid drought-prone climate in Yangling(108°24′E, 34°20′N; 521 m a.s.l.), Shaanxi Province, China, to explore the effects of mulching(same for summer maize and winter wheat) on soil moisture, soil temperature, crop water consumption, and crop yield with a winter wheat/summer maize rotation. Crops were planted in a ridge-furrow pattern and the treatments consisted of a transparent film mulch over the ridges(M1), a crop straw mulch in the furrows(M2), a transparent film mulch over the ridges and a crop straw mulch in the furrows(M3), a black film mulch over the ridges and a crop straw mulch in the furrows(M4), and a control with no mulch(CK). Results showed that M4 was the best treatment for improving soil water storage and content, and decreasing crop water consumption during the summer maize and winter wheat rotation. In both maize and wheat seasons, M1 had a higher soil temperature than M2 and CK, and M3 had a higher soil temperature than M4. In the maize seasons, M4 had the highest yield, WP, and precipitation productivity(PP), with the average values for these parameters increasing by 30.9%, 39.0%, and 31.0%, respectively, compared to those in CK. In the wheat seasons, however, M3 had the highest yield, WP, and PP, with the average values for these parameters being 23.7%, 26.7%, and 23.8% higher, respectively, than those in CK. Annual yield(maize and wheat yields combined) and WP did not differ significantly between M3 and M4. These results suggested that M3 and M4 may thus be the optimal ARH practices for the production of winter wheat and summer maize, respectively, in arid and semi-arid areas.     

Improving Lettuce Yield and Quality of an Agricultural Soil Using a Combination of Arbuscular Mycorrhizal Fungus and Phosphate-Green Wastes Compost

The use of biofertilizers on agricultural soils could act positively to improve soil fertility and crop productivity. This work was performed to assess the potential beneficial impacts of local produced phospho-compost and/or an exogenous arbuscular mycorrhizal fungus (AMF) (Rhizoglomus irregulare DAOM 197198) on lettuce agro-physiological and soil characteristics under filed conditions. Four treatments were applied: control treatment without any biofertilizer, compost, AMF, and compost?+?AMF treatments. Obtained results showed that shoot nitrogen (N) and phosphorus (P) were significantly improved in lettuce plants treated with compost supplementation and/or AMF inoculation compared to the control with a maximum increment for P in plants treated with compost (106%). As for growth traits, lettuce plants treated with compost?+?AMF recorded the highest values in terms of shoot and root dry weights and yield by 121, 54 and 127%, respectively, compared to the control plants. Considering physiological and biochemical traits, stomatal conductance, and chlorophyll fluorescence as well leaf area index and total soluble sugar and protein concentration were significantly improved in plants treated with compost and/or AMF compared to the control. In addition, soil properties, especially the soil total organic carbon, N, P, and glomalin-related soil protein content were significantly enhanced after two months of field experiment in treated soils with the applied biofertilizers alone or in combination compared to the control. Based on the main obtained results, applied biofertilizers were able to increase lettuce productivity and soil fertility under field conditions, especially the compost?+?AMF treatment, which demonstrated an effectiveness promotion of lettuce productivity and soil fertility.

     

Morpho-physiological Responses of Tomato Genotypes Under Saline Conditions

Gesunde Pflanzen - Salinity is a&nbsp;complex abiotic stress that affects physiology and biochemistry of plants and significantly reduces both crop yield and quality. Considering the global...     

Effects of variation in rainfall on rainfed crop yields and water use in dryland farming areas in China

Crop production in the dryland farming areas of northern China is constrained by low and variable rainfall. This article presents the analysis of the relationships between variations in rainfall and yields of winter wheat and spring maize. The analysis is based on data from both several short-term and our ongoing long-term field experiments in dryland farming research projects in Tunliu, Linfen, Shouyang, and Luoyang. Grain yields of wheat and maize ranged from 1,548 to 5,169 and from 2,612 to 8,789 kg ha^-1 respectively, with differences up to above 200% (between dry and wet years). Wheat yields are sensitive to growing season rainfall but also correlated to water use (ET), whereas maize yields are sensitive to the critical time of water supply (especially June rainfall) but not correlated to ET. The ratio of grain yields to soil water at sowing is an important indicator, showing close relationships between yields and soil water-related ratio within the rainfed crops site. Comparison between the indices of water use efficiency (WUE) and precipitation use efficiency (PUE) suggests that the index WUE is more grain-related indicator than the PUE used for assessing rainfed crop water use by both maize and wheat. The index PUE should be used in caution, especially for wheat crops in dry years. Our results indicate that options to alleviate crop moisture stress must be tailored to the rainfall pattern. This holds especially for conservation tillage with response nutrient management practices that aim at enhancing water use efficiency.     

生物炭对不同水氮条件下小麦产量的影响

研究生物炭与氮肥互作在不同水分条件下对小麦关键生育期旗叶光合参数、产量与主要农艺性状的影响,探讨生物炭改良不同水肥条件土壤并提高其作物产量的效果与内在机理,可为农田有机物资源合理利用提供理论支撑。本研究采用盆栽试验,生物炭用量设置五个水平(0,1%,2%,4%和6%),氮肥设置N0,N1和N2(0,0.2 g·kg~(-1)和0.4 g·kg~(-1))三个水平,小麦拔节期控制土壤田间持水量的80%和50%模拟正常水分和干旱胁迫两种水分环境。于小麦拔节期和抽穗期测定旗叶光合参数和SPAD值,成熟后对小麦籽粒产量及主要农艺性状进行统计。结果显示:(1)与不施生物炭处理相比,1%和2%生物炭用量平均增产6.62%和11.01%,4%和6%生物炭用量平均减产6.88%和10.1%,同时会导致千粒重、穗粒数和株高的降低;(2)正常水分条件下,1%和2%生物炭用量与N1和N2之间存在协同增产作用,而4%和6%生物炭用量表现出负面效应;(3)干旱胁迫条件下,仅1%和2%生物炭用量与N1存在协同增产作用,生物炭处理削弱N2增产潜力;(4)N0水平下,生物炭处理均表现出促进小麦旗叶光合速率,增加产量的作用;(5)N1条件下,生物炭促进小麦旗叶光合速率且在干旱胁迫条件下效果更明显。总体上生物炭对小麦旗叶光合参数和产量的影响受生物炭用量、氮素水平和水分条件共同制约且存在复杂的交互作用,干旱会限制生物炭与氮肥的协同增产作用;在低肥力土壤上应用生物炭的增产效果较好,而在质地较细且肥力中等的土壤应用时推荐48 t·hm~(-2)(2%)生物炭用量。     

不同施氮水平下小麦/玉米套作群体产量和水氮利用

通过2018—2020年连续两年田间试验,以小麦/玉米套作群体为试验对象,研究N0、N1和N2 3个水平下（施N量分别为小麦0、120 kg·hm^-2和240 kg·hm^-2,玉米0、180 kg·hm^-2和360 kg·hm^-2）小麦/玉米套作群体产量、土地当量比与土壤水分利用的差异。结果表明：小麦/玉米套作具有明显的产量与水分利用优势,与单作相比,套作小麦产量提高21.34%~27.80%（P＜0.05）,产量优势主要来源于边1行与边2行的增产,而套作玉米表现受氮肥供应的调控,在N0与N1水平下套作产量减少3.02%~11.43%,仅在N2水平下高于单作玉米;小麦/玉米套作群体的土地当量比（LER）在1.04~1.16,具有土地利用优势;在相同产量下小麦/玉米套作群体比单作群体的耗水量更少,水分利用效率更高,其中在N1水平下耗水量减少最为明显,两年内平均减少消耗47.30 mm的水分,而水分利用效率比单作系统提高2.77%~6.46%,小麦/玉米套作群体在3个施氮水平下均表现出节水与水分利用优势;套作种植还可以提高小麦和玉米的氮肥农学利用率及小麦的氮肥偏生产力,两年内套作小麦的氮肥偏生产力和氮肥农学利用率最高可达64.17 kg·kg^-1和11.17 kg·kg^-1。因此在半湿润区雨养条件下具有发展小麦/玉米套作种植模式的可行性。     

Impact of Exogenous Application of Salicylic Acid on Growth,Water Status And Antioxidant Enzyme Activity of Strawberry Plants (Fragaria vesca L.) Under Salt Stress Conditions

Irrigation with saline water can act as an alternate water resource and thus plays an important role in saving freshwater resources as well as promoting agriculture. Furthermore, salinity stress is considered one of the major abiotic stress factors, which strongly reduces crop productivity. In this context, the present work was conducted to examine the effect of exogenous salicylic acid (SA) application on salt stress tolerance of strawberry plants. For this purpose, strawberry plants (Fragaria vesca L.), three months old, were treated with three SA concentrations (0?mM, 0.25?mM and 0.5?mM), then subjected to 80?mM NaCl or not. After five weeks of treatment, growth responses, water status, photochemical efficiency and oxidative stress indicators were measured. The obtained results showed that irrigation with saline water negatively affected the growth parameters, the leaf water potential (LWP), the relative water content (RWC), the stomatal conductance (gs) and photochemical efficiency (Fv/Fm). While, the total protein content, the electrolyte leakage (EL), the malondialdehyde (MDA) and the hydrogen peroxide (H₂O₂) contents were increased in stressed plants compared to unstressed ones. Salt stress also leads to the activation of the antioxidant enzymes. However, the exogenous application of SA under salt stress conditions reduced the H₂O₂ accumulation, the electrolyte leakage and the MDA content. It has also improved the growth parameters, the LWP, the RWC, the gs, the Fv/Fm, the protein content and the antioxidant enzyme activities (POD, CAT and SOD) in the treated plants compared to those without SA application. Therefore, the beneficial effect of 0.25?mM SA on Fragaria vesca L. salinity tolerance may provide some practical basis for strawberry cultivation under saline conditions.

     

Arbuscular Mycorrhizal Fungi Alleviate the Negative Effect of Temperature Stress in Millet Lines with Contrasting Soil Aggregation Potential

Arbuscular mycorrhizal fungi (AMF) establish a mutualistic symbiosis with several plants and play a key role in improving plant growth, tolerance to abiotic and biotic stresses as well as the soil structure. This work aimed at elucidating the AMF temperature stress modulating impact on four pearl millet lines plant growth and soil aggregation. Experimental trials were carried out in both greenhouse and growth chamber to determine the response of the four millet lines to inoculation with two AMF strains (Rhizophagus aggregatus and Funneliformis mosseae) under heat and non-stress conditions. We first investigated the mycorrhizal colonization (MC) and the mycorrhizal growth response (MGR) of millet lines in relation with their soil aggregation potential (root adhering soil/root biomass, MAS/RB) in the greenhouse. Secondly, the four millet lines were grown in two separated growth chambers and subjected to a day/night temperature of 32/28?°C as the control treatment and 37/32?°C as the temperature stress treatment. Plant growth, mycorrhization rate and several physiological, mycorrhizal and soil parameters were measured. Results showed that the mycorrhization rates of millet lines were low and not significantly different. Funneliformis mosseae (31.39%) showed higher root colonization than Rhizophagus aggregatus (22.79%) and control (9.79%). The temperature stress reduced the mycorrhizal colonization rate, shoot and root biomass, and the soil aggregation for all tested lines. L220 and L132 showed more MC rate and MGR than the other lines under control and high-temperature treatment. The MGR was significantly better under temperature stress conditions than in the control. Under the temperature stress conditions, inoculation with R. aggregatus and F. mosseae increased chlorophyll concentration, root dry weight and shoot dry weight as compared to non-inoculated plants. AMF inoculation, particularly with F. mosseae had a positive influence on the tolerance of millet lines to temperature stress. This study demonstrates that AMF play an important role in the response of these four millet lines to temperature stress. AMF is therefore an important component in the adaptation of crops to climatic variations in Sub-Saharan Africa.

     

Interaction Effect of Water Magnetization and Water Salinity on Yield,Water Productivity and Morpho-Physiological of Balkız Bean (Phaseolus vulgaris)

Developing new tools for using low-quality irrigation waters is vital for the sustainability of irrigated agriculture and minimizing salt accumulation. Therefore, the present study focused on the interactive influence of irrigation treatments (magnetized (MT) and non-magnetized (NMT)) and water salinities (0.38, 1.5, 4.5, and 7.0?dSm^?1) on soil salinity, water use efficiency, yield and morpho-physiological changes of Balk?z bean. A pot experiment was conducted in a randomized complete block design with three replications under the rain shelter condition. Irrigation water MT treatment increased fresh bean yield, water use efficiency (WUE) and irrigation water use efficiency (IWUE) by 21.35, 23.00 and 14.8%, respectively, while saturated soil salinity was reduced by 20%, compared to NMT treatments. The leaf area, stomata, and leaf succulence in green beans in the MT treatment significantly increased by 13.4, 23.9, and 3.3% compared with those in the NMT treatment. Stems of the bean crops were more sensitive to salinity stress followed by roots and leaves. The study revealed that irrigation with magnetically treated water manages salinity related yield loss through increased morphological features as well as osmotic and stomatal adjustments. In addition, the bean crops showed an ability to protect water in tissue against salinity toxicity up to 5.24?dSm^?1 soil salinity level under magnetized saline water conditions. Finally, irrigation with magnetically treated 0.38?dSm^?1 irrigation water can be recommended due to providing a higher yield, WUE, IWUE, and sustainable production under saline irrigation in water scarcity regions.

     

Seed Development,Oil Accumulation and Fatty Acid Composition of Drought Stressed Rapeseed Plants Affected by Salicylic Acid and Putrescine

Two field experiments were carried out in 2017 and 2018 to evaluate the impacts of salicylic acid (1?mM SA) and putrescine (1?mM Put) on leaf osmolytes, seed reserve and oil accumulation and fatty acid composition of rapeseed (Brassica napus L.) under different watering levels (irrigations after 70 and 150?mm evaporation as normal irrigation and severe drought stress, and 70?→?90?→?110?→?130?→?150 and 70?→?100?→?130→150 as gradual and moderately gradual water deficits, respectively). The experiments were laid out as split plot on the bases of randomized complete block design in three replications. Water stress increased the contents of glycine betaine, proline, soluble sugars, and proteins. Application of SA and Put further enhanced the contents of glycine betaine and soluble sugars, while reduced proline content of leaves. Seed filling duration, seeds per plant, plant biomass and seed yield were decreased with increasing irrigation intervals. Exogenous SA and Put enhanced all of these parameters under different irrigation intervals. Oil accumulation in seeds was diminished as water stress severed. The gradual water deficit considerably reduced the impacts of drought stress on yield related traits and oil content per seed, due to stress acclimation of plants. Oil content of seeds was augmented by SA and Put treatments through prolonging seed filling duration, particularly under limited irrigations. Percentages of palmitic acid and stearic acid (saturated fatty acids) were not affected by water limitation. However, unsaturated fatty acids of linoleic and linolenic acids were reduced, and oleic acid was enhanced due to water shortage. Unsaturation index was improved by SA and Put treatments under severe water stress as a result of decreasing oleic acid and increasing linoleic and linolenic acids contents. The SA spray was the best treatment for improving rapeseed seed and oil production under normal and stressful conditions.

     

Prolonged Waterlogging Reduces Growth and Yield in Broccoli Plants (Brassica oleracea var. italica)

The crop of broccoli in tropical regions is of great importance among flowering vegetables; however, the yield of this crop is severely impacted by climatic variations that can cause floods. In Tunja, Colombia, a study was carried out under greenhouse conditions in which the tolerance of broccoli plants to prolonged waterlogging was evaluated. One group of plants were kept under waterlogging conditions until most of them showed severe symptoms of chlorosis while another group was grown under regularly drained and watered soil conditions as a control. Waterlogging caused the death of 20% of the plants, reduced the height of the plants by 42.9%, the thickness of the stem by 42.1%, the foliar area by 87%, the chlorophyll content in the leaves by 96.6%, and the total dry weight per plant by 79.9%. The absolute and relative growth rates decreased by 80 and 24.4%, respectively. Waterlogging also prevented flower production and caused a 23.7% increase in the accumulation of biomass in roots but reduced it by 24.5% in leaves. Likewise, the net assimilation rate fell 72.3% when waterlogged and the values of allometric variables which express growth were altered by this stressor. Consequently, it can be inferred that these plants have a low tolerance to waterlogging; however, the most severe impact caused by waterlogging was the inability of plants to develop flowers. The lack of flowers is devastating due to their economic and commercial importance of broccoli, and they are the primary justification for the cultivation of these plants.