Increasing Irrigation Intervals Research Articles

Water deficit stress mitigation by foliar application of potassium silicate for sugar beet grown in a saline calcareous soil

Drought stress is a serious abiotic factor that limit yield and quality of many crops grown in newly reclaimed lands of Egypt. A field experiment in split-plot design was conducted to assess the usefulness of potassium silicate [K2SiO3 (K-silicate)] on alleviating drought stress on sugar beet grown in a calcareous soil. The main plots were assigned for three irrigation intervals as 8, 14 and 20 days, whereas the subplots were assigned for four K-silicate foliar spray concentrations (0, 500, 1000 and 2000 mg L-1 silicate). The results indicated that increasing the irrigation interval from 8 to 14 and 20 days caused a significant reduction in sugar beet yield. However, irrigation with interval 14 days and spraying K-silicate at concentrations of 1000 mg L-1 silicate gave root fresh yield of 51.65 Mg ha-1, compared with 38.81 mg L-1 obtained without spraying K-silicate. Likewise, spraying K-silicate in concentration of 1000 mg L-1 silicate increased N, P and K removal in shoot by 66.0, 15.5 and 134.2 kg ha-1 and in root by 152.0, 34.4 and 244.2 kg ha-1, respectively. These values were 64.6, 14.2 and 122.6 kg ha-1 in shoot and 128.4, 29.0 and 223.1 kg ha-1 in root without spraying K-silicate, respectively. Spraying K-silicate showed also the potential to increase fertilizer use efficiency, and hence can save fertilizers. For instance, increasing irrigation interval to 14 days without spraying K-silicate gave partial factor productivity (PFP) of N, P and K fertilizers to the levels of 647, 1252 and 1552 kg root kg-1 fertilizer, respectively. However, spraying K-silicate at concentration of 1000 mg L-1 silicate increased these values to 861, 1666 and 2066 kg root kg-1 fertilizer, respectively. In conclusion, this study suggests that spraying K-silicate has the potential to alleviate the negative effects of drought stress on sugar beet yield grown in calcareous soils.

Effect of irrigation, nitrogen levels and methods of fertilizer application on growth, yield and profitability of yard long bean [Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt

A field experiment was conducted during the summer, 2014 at College of Agriculture, Vellayani, Kerala to evaluate the influence of irrigation levels, nitrogen stress and method of application of fertilizers on growth and yield of yard long bean. The experiment consisted of four levels of irrigation, two levels of nitrogen and two methods of application. The results indicated that daily irrigation at 10 mm depth and recommended dose of nitrogen (30 kg ha-1) recorded superior values for growth parameters viz., functional leaves per plant and leaf area index The major yield attributes like number of pods per plant and pod yield per plant and total pod yield were not influenced by levels of irrigation and nitrogen indicating that irrigation once in three days at 20 mm depth and nitrogen level of 22.5 kg ha-1 is sufficient for yard long bean. Soil and foliar application of nitrogen and potassium recorded superior growth characters, however, the yield was superior when the recommended dose of nutrients were supplied as soil application. Increasing irrigation interval to three days and imparting N stress did not result in any reduction in gross income and net income while, a higher benefit: cost ratio was noted in irrigation at wider intervals. Soil application of nutrients recorded higher gross income, net income and BCR compared to soil + foliar application.

EFFECT OF IRRIGATION INTERVALS AND SOME ANTITRANSPIRANTS ON GROWTH AND YIELD OF SNAP BEAN (PHASEOLUS VULGARIS L) UNDER DRIP IRRIGATION SYSTEM IN CLAY LOAM SOIL

The objective of this work is to reduce the quantity of water applied by irrigation, increase the water use efficiency and determine the appropriate period for irrigation snap bean, a field experiment was implemented at the Experimental Station of Vegetable Research Department, Horticulture Research Institute, Agriculture Research Center, Giza Governorate, during the two growing summer seasons of 2016 and 2017. This study involved three irrigation intervals (2, 4 and 8 days) under clay loam soil using drip irrigation system, with spraying the plants by five antitranspirant substances (control, kaolin at 3 g/L, MgCo3 at 3 g/L, liquid paraffin 2% and bentonite 2%), The results showed that increasing irrigation intervals from 2 days to 8 days decreased the total water content in the leaves, the rate of relative transpiration, whereas caused an increase in the leaf water deficit. While, reducing the irrigation interval from 8 days to 2 days led to a significant increase in vegetative growth parameters i.e. plant height, number of branches, number of leaves, leaf area and plant weight, but dry matter percent was decreased. The yield and pods quality of the plants irrigated every 2 days showed higher values and best quality than the other periods of irrigation, the highest values of N,P and K content in the pods and chlorophyll in the leaves were found with irrigation every 2 days. Spraying snap bean plants with MgCO3 followed by spraying with kaolin led to the highest total water content, the lowest relative transpiration and the lowest leaf water deficit. The best growth characters, yield and pods quality, N, P and K concentrations and chlorophyll content were obtained from the plants sprayed by MgCO3 followed by spraying with kaolin. On the other hand, the interactions treatments between irrigation intervals and antitranspirants resulted in a significant effect in many studied parameters whereas, the superior treatment for obtained strong vegetative growth, high pods yield with best quality was the interactions between irrigation every 2days and spraying the plants with MgCo3 at 3g/L three times, the first one at vegetative growth stage (at 3-4 true leaf stage) and the others after two weeks interval of the first one.

Potassium Fertilization Role in Tomato Tolerance of Water Salinity and Stress under Drip Irrigation System

A study was carried out on a field scale during two successive growth seasons (2009/2010 and 2010/2011) on tomato plants irrigated with saline ground water (2.24 and 3.86 dS m-1) using drip irrigation system, subjected to water stress (irrigation every 3, 4, and 5 days), and were grown under application of potassium fertilization (96, 120, and 144 kg K2O/feddan) in newly reclaimed lands at the Agricultural Experiments and Research Center, Faculty of Agriculture, Minia University, El-Minia Governorate, Egypt. The current study aims to investigate the effects of irrigation water salinity and water stress on tomato growth, tomato yield, and tomato fruit quality under application of a salinity and water stress alleviated amendment (potassium fertilization) using drip irrigation system. The obtained results of the current study showed that increasing irrigation water salinity level from 2.24 dS m-1 to 3.86 dS m-1 decreased tomato plant height, tomato shoots fresh weight, average tomato fruit weight, fresh tomato fruit yield, and tomato fruit dry weight, while, it increased tomato shoots dry weight, number of tomato fruits per plant, total soluble solids of tomato, and tomato fruits marketability (shelf life) in growth seasons. Increasing irrigation interval from 3 up to 5 days decreased tomato shoots fresh weight in both growth seasons, however, it increased tomato shoots dry weight, total soluble solids, and tomato fruits marketability in the two growth seasons. Increasing the potassium fertilization level from 96 up to 144 kg K2O/feddan increased the tomato plant height, tomato shoots dry weight, average tomato fruit weight, total soluble solids of tomato, and tomato fruits marketability. Increasing the potassium fertilization level from 96 to 120 or 144 kg K2O/feddan increased the tomato shoots fresh weight, number of tomato fruits per plant, fresh tomato fruit yield, and tomato fruit dry weight in the two growth seasons. The increase in the tomato plant height, tomato shoots fresh weight, tomato shoots dry weight, number of tomato fruits per plant, average tomato fruit weight, fresh tomato fruit yield, total soluble solids of tomato, tomato fruits marketability, and tomato fruit dry weight implies that application of potassium fertilization to soil alleviated adverse effects of salinity stress and water stress on tomato growth, tomato yield, and tomato fruit quality. The results of the current research indicated that it can be recommended that to alleviate and manage adverse effects of salinity stress and water stress on tomato growth, tomato yield, and tomato fruit quality, good cultural practices management to be followed are: (1) irrigate tomato plants every 4 days, (2) apply appropriate and optimized requirements of potassium fertilization to soils (120 kg K2O/feddan), and (3) use drip irrigation system as an irrigation management which might control soil salinity build-up and soil water content since it can keep a high soil water content and low salt concentration in the root zone.

Field performance of maize (Zea mays L.) cultivars under drought stress

This research was carried out in 2014 at the Research Farm of the University of Tabriz, Iran. The experiment was arranged as split plot on the basis of randomized complete block with three replicates to assess the effects of four irrigation intervals (irrigations after 60, 80, 100 and 120 mm evaporation) on physiological and agronomical traits of three cultivars of maize (Zea mays L.; ‘SC704’, ‘NS640’, ‘DC303’: late, mid and early maturing, respectively). Irrigation intervals and maize cultivars were assigned to the main and sub-plots, respectively. Leaf temperature of all maize cultivars significantly increased, but chlorophyll content index, maximum efficiency of photosystem II, number of grains per plant, 1000 grain mass, plant biomass, grain yield and harvest index significantly decreased with increasing irrigation intervals. Late maturing cultivar (‘SC704’) was superior in all studied traits, followed by mid (‘NS640’) and early (‘DC303’) maturing cultivars. It was concluded that water limitation can potentially reduce performance of maize cultivars in the field, but the extent of this reduction depends on genotype and severity of stress.

Water use efficiency of three mycorrhizal Lamiaceae species (Lavandula officinalis, Rosmarinus officinalis and Thymus vulgaris)

As a mechanism of plants to adapt to soil water deficits, promotion of water use efficiency has been the focus of strategies to increase crop tolerance to drought. Probable improvement of arbuscular mycorrhizal fungi (Funnelliformis mosseae or Rhizophagus irregularis) for the essential oil and biological yield of watered and rainfed host plants (lavender, rosemary and thyme) are the main aim of this study. Physiological responses of the host plants to inoculation with two species of fungi were evaluated under different irrigation regimes (irrigation at 75 and 50% of field capacity, and rainfed). A factorial (two factors) experiment was conducted for two years (2015–2016) based on a randomized complete block design with three replications at Urmia University. Inoculation with these root symbionts increased the colonization of the plants as compared to non-inoculated plants. The seedlings inoculated with fungi and subjected to water stress had more successful colonization. Stress reduced biological yield of inoculated and non- inoculated plants. Drought-induced reduction of biomass was significantly compensated for by mycorrhizal fungi. The highest essential oil percentage was obtained in rainfed condition. Since water use efficiency is affected by economic performance and volume of used water in different years, the results were variable. Increasing irrigation intervals can help the plants to adapt to water stress and prevent significant reduction in water use efficiency. However, in general, this study showed that inoculation with fungi is effective in alleviating adverse effects of water stress.

Response of Biomass Development, Essential Oil, and Composition of Plectranthus amboinicus (Lour.) Spreng. to Irrigation Frequency and Harvest Time.

A greenhouse experiment was conducted to study the effects of four irrigation intervals (4, 8, 12, and 16 days) and six harvests (2, 4, 6, 8, 10, and 12 months after transplanting) on biomass, essential oil content, and composition of Plectranthus amboinicus (Lour.) Spreng. Fresh weight and essential oil yield decreased with increasing irrigation interval; whereas, essential oil content was stimulated by water stress and increased as the irrigation interval increased. Fresh weight of Plectranthus amboinicus irrigated every 4 days peaked when harvested at 6 months, but essential oil content peaked when irrigated every 16 days and harvested at 2 months after transplantation. On the other hand, essential oil yield peaked when irrigated every 8 days and harvested at 6 months. Thymol, p-cymene, γ-terpinene, and β-caryophyllene were the major compounds, and they peaked at different irrigation intervals and harvest times. This study showed biomass, essential oil content, and yield as well as the major and minor constituents of Plectranthus amboinicus are influenced by irrigation interval and the timing of harvest.

Influence of Irrigation Intervals under Different Sowing Dates on Water Relations, Yield and Quality Nutrition of Guar Forage Crop

TWO FIELD experiments were conducted at Giza Agriculture Research Station during the two growing seasons of 2015 and 2016. The investigation was carried out to study the effect of different irrigation intervals, i.e., two weeks and three weeks in combination with different sowing dates, i.e., 1st April ,15th April , 1st May and 15th May on Guar forage crop (Cyamopsis tetragonoloba L.,var. Shandaweel 1 ) crop - water relations, yield and yield components under middle Egypt conditions. The main results could be summarized as follows:-The number of applied irrigations and seasonal water consumptive use (CU) were increased with decreasing irrigation interval days which the shortage irrigation interval (irrigation every 15 days) recorded the maximum CU under all sowing date with an overall average being 442 and 453 mm for first and second season, respectively. The same trend was found with sowing date, with plant sown in 1st April consumed more water than the other sowing dates. The lowest water use efficiency (WUE) was recorded under longer irrigation interval (irrigation every 21days) comparable to (irrigation every 15 days) and values of WUE differed due to sowing date, which the S4 (sowing at 15th May) gave the lowest WUE while, S1( sowing at 1st April) obtained the highest value. The crop coefficient (Kc) values started small and increased to reach their maximum values in mid season under all sowing dates, then decline again until the crop maturity under all sowing dates.All yield and yield component traits were markedly affected by sowing date and irrigation interval. Most of the studied traits except leaves/stem ratio as well as fiber %, decreased by delaying sowing date from 1st April to 15th May. Decreasing irrigation interval days from 21 to 15 days significantly increased plant height, number of branches/plant, fresh and dry yield ton fad-1, while leaves/stem ratio and crud fiber% which increased by increasing irrigation intervals from 15 to 21 days.

EFFECT OF IRRIGATION INTERVALS, FERTILIZER LEVELS AND PLANTING METHODS ON YIELD AND WATER USE EFFICIENCY

This work was carried out during summer and winter seasons at Gharbia Governorate ,to study the effect of irrigation intervals ( every14, 21 and28 day ),fertilizer levels (40 ,50 and 60uN/ fed) , planting methods ( row and two rows) and interaction between them on irrigation water quantity, total yield and water use efficiency of okra and garlic crops . Data show that decreasing when irrigation intervals increase from every 14 days to every 21 and with a bout 5.89 and 17.50% for okra and about 11.60 and 25.27 % for garlic respectively. Meanwhile irrigation water quantity increases by increasing fertilizer levels from 40 to 50 and 60 uN/ fed by 8.60, 15.66 % for okra and about ,5.00 and 11 % for garlic respectively. Planting on two rows save irrigation water quantity by 12.09 and 14.54 % for okra and garlic crops respectively compering by planting on one row .Increasing irrigation intervals decrease the yield of okra by 6.00 and 9.8 % but increase the garlic by about 8.73and 18.59 % for irrigation every 21 and 28 day compering by irrigation every 14 days . Also, data show that increasing fertilizer levels from 40 to 50 and 60 uN / fed increase the okra yield by 9.06 and 18.53%respectivily for 50 and 60 uN/ fed compered by40 uN /fed of okra crop. The same trend was happened for the garlic yield but increasing percent was about 6.40 and 7.73 % respectively. Water use efficiency affected by irrigation intervals, fertilizer levels, planting methods and interaction between them. Increasing irrigation intervals to 21and 28 days compered by irrigation every 14 day decrease the WUE by about 6.3and 18 %, resp. for okra crop. While for garlic crop, increasing irrigation intervals increase WUE by 13.3 and 16.53 %, resp. Moreover increasing fertilizer levels, increased WUE by 3.06 and 4.37% for okra and 2.47 and 3.73 % for garlic under 50 and 60 uN / fed compared with 40 uN / fed resp. The same trend happen in planting methods. Using two rows increased the WUE by 17.59 and 25.67 % for okra and garlic crops, resp.

Effect of Drought Stress and Fe Nano-fertilizer on Seed Yield, Morphological Traits, Essential Oil Percentage and Yield of Dill (Anethum graveolens L.)

Dill (Anethum graveolens L.) from parsley family (Apiaceous) is an annual plant. Essential oils of dill are used in various food processing industries, pharmaceutical and health. In this study the effects of iron nano-fertilizer and different levels of irrigation on seed yield, morphological traits, yield and percentage of essential oil of dill were studied. A factorial experiment based on completely randomized design (CRD) with three replications was conducted at Laboratory, Payam Noor University of Uromia in Iran in 2015. Treatments were including irrigation with 5 levels (5, 7, 9, 11 and 13 days) and nano iron fertilizer in one level (no fertilizer (control) and fertilizer nano-iron the amount of 4 liters per hectare with irrigation water). Analysis of variance showed that the effect of nano Fe and effects of different levels of irrigation was significant on seed yield, morphological traits, yield and percentage of essential oil of dill. Also the interaction effects of nano iron fertilizer and irrigation were significant on morphological traits. Mean comparison showed the highest and lowest seed yield, morphological traits, yield and percentage of essential oil of dill obtained by applying nano iron fertilizer and control treatments (no fertilizer), respectively. The highest percentage of essential oil obtained from moderate drought stress (irrigation 9 days), respectively. The highest seed yield, morphological traits and essential oil percentage and yield achieved by irrigation 5 and 7 days. With increasing irrigation interval and severity of drought stress, studied different traits decreased significantly. According to these results, in order to protect the environment and reducing pollution, can be used nano fertilizer instead of chemical fertilizers with high consumption and permanent that it was leading to sustainable agriculture. Also in order to obtaining maximum yield and essential oil percentage of dill irrigation interval of 7 days recommended.

Diferentes turnos de rega sobre o crescimento e produção de Macroptilium lathyroides (L.) Urb

The use of native forage species adapted to the climatic conditions of the Brazilian semiarid region is an alternative to increasing the regional livestock productivity. In this sense, the objective of the present study was to evaluate the growth characteristics and production of Macroptilium lathyroides (L.) Urb. when subjected to different irrigation frequency. The experimental design was a randomized complete block design with five treatments and six replications, where the treatments consisted of five irrigation shifts corresponding to the irrigation intervals 2, 4, 6, 8 and 10 days. It was not observed effect of watering shifts to produce litter. For the number of leaves, decrease fitting 30 for 11 sheets with increased irrigation interval. Dry matter production of forage presented exponential fit, with greater reduction to the 4 day irrigation schedule. The other variables linearly decreased with the increase in frequency of irrigation. The increase in the range of irrigation frequency promotes reduction in the growth and production of Macroptilium lathyroides (L.) Urb. The two days irrigation interval revealed as the least restrictive to their development.

Arbuscular mycorrhizal fungi and Pseudomonas in reduce drought stress damage in flax (Linum usitatissimum L.): a field study.

Drought stress, which is one of the most serious world environmental threats to crop production, might be compensated by some free living and symbiotic soil microorganisms. The physiological response of flax plants to inoculation with two species of arbuscular mycorrhizal (AM) fungi (Funneliformis mosseae or Rhizophagus intraradices) and a phosphate solubilizing bacterium (Pseudomonas putida P13; PSB) was evaluated under different irrigation regimes (irrigation after 60, 120, and 180mm of evaporation from Class A pan as well-watered, mild, and severe stress, respectively). A factorial (three factors) experiment was conducted for 2years (2014-2015) based on a randomized complete block design with three replications at Urmia University, Urmia, located at North-West of Iran (37° 39' 24.82″ N44° 58' 12.42″ E). Water deficit decreased biomass, showing that flax was sensitive to drought, and AM root colonization improved the performance of the plant within irrigation levels. In all inoculated and non-inoculated control plants, leaf chlorophyll decreased with increasing irrigation intervals. Water deficit-induced oxidative damage (hydrogen peroxide, malondialdehyde, and electrolyte leakage) were significantly reduced in dual colonized plants. All enzymatic (catalase, superoxide dismutase, glutathione reductase, and ascorbate peroxidase) and non-enzymatic (glutathione, ascorbic acid, total carotenoids) antioxidants were reduced by water-limiting irrigation. Dual inoculated plants with AM plus Pseudomonas accumulated more enzymatic and non-enzymatic antioxidants than plants with bacterial or fungal inoculation singly. Dual colonized plants significantly decreased the water deficit-induced glycine betaine and proline in flax leaves. These bacterial-fungal interactions in enzymatic and non-enzymatic defense of flax plants demonstrated equal synergism with both AM fungi species. In conclusion, increased activity of enzymatic antioxidants and higher production of non-enzymatic antioxidant compounds in symbiotic association with bacteria and mycorrhiza can alleviate reactive oxygen species damage resulting in improve water stress tolerance.

Response of fodder sorghum (Sorghum bicolor (L.) to sewage sludge treatment and irrigation intervals in a dryland condition

A field experiment was conducted in the Experimental Research Farm of Omdurman Islamic University, Sudan to determine short-term effect of irrigation intervals (7 and 10 days) and sun-dried or composted sewage sludge, recommended mineral fertilizer on straw dry matter yield (SDMY) and N, P and K content of fodder sorghum and soil properties. In the 7 and 10 days irrigation intervals, composted, sun-dried sludge and mineral fertilizer have significantly increased SDMY over the control by 51, 98, 67 and 78, 19, 33%, respectively. Apparent N use efficiency (ANUE) in composted and sun dried plots irrigated at either 7 or 10 days was 9 - 36 and 16 - 74%, respectively. Reducing the irrigation interval has significantly increased salinity by 13%. Increasing irrigation interval has decreased bulk density by 5%. It could be concluded that, application of composted sludge is a useful practice for improvement of soil properties and consequent yield increase.

Effects of irrigation intervals and organic manure on morphological traits, essential oil content and yield of oregano ( Origanum vulgare L.).

In order to evaluate the effect of irrigation intervals and cattle manure levels on morphological traits, essential oil content and yield of oregano, an experiment was conducted at the experimental Farm of the Faculty of Agriculture, Urmia University, Iran. The experimental design was split-plots, arranged in randomized complete blocks with three replications. Main plots including irrigation intervals (1, 2 and 3 weeks) and four levels of cattle manure at 0, 10, 20 and 30 t ha-1 were allocated to sub plots. Our results showed that increasing irrigation intervals reduced values of all morphological traits except for proportion of stems. Also, values for stems number, plant spread, stem diameter, leaf area, fresh and dry herb yield increased by increasing cattle manure levels. On the other hand, morphological traits not influenced by interaction of treatments except for plant spread and leaf area. The highest essential oil content (2.07%) and yield (66.62 kg ha-1) obtained in highest irrigation intervals and cattle manure levels. Whereas, 1 week irrigation interval without use of cattle manure produce lowest essential oil content (1.55%). For essential oil yield, the lowest value (46.37 kg ha-1) was found in 2 weeks irrigation interval with application of 20 t ha-1 cattle manure.

Changes in seed oil and protein contents of maize cultivars at different positions on the ear in response to water limitation

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.

The influences of Bio-stimulator Compounds on growth, essential oil and chemical composition of chamomile plants grown under water stress

This study was conducted at the Experimental Nursery of the Ornamental Horticulture Department, Faculty of Agriculture, Cairo University, Giza, during the two successive seasons of 2013/2014 and 2014/2015. This work aimed to investigate the effect of water stress and bio- stimulator on the vegetative growth, flower yield, essential oil production and chemical compositions of Chamomile ( Matricaria chamomilla L.). Water stress was imposed by three different irrigation intervals (4, 8 and 12 days). The plants received different irrigation intervals were sprayed every 2 weeks with bio-stimulator of either Amino Suam or Setter-2 at concentration of 500, 1000 and 2000 ppm for each one, while the control plants were sprayed with tap water. The experimental units were designed in randomized complete block design (RCBD) with 21 treatments and three replications for everyone treatment. The results showed that, highest values of plant height, number of branches/plant , diameter of flower heads, essential oil percentage, total chlorophylls content and total carbohydrates percentage were obtained from irrigation interval of 8 days as a compared to 4 or 12 days. Increasing irrigation intervals from 4 to 8 or 12 days resulted in a significant reduction in the stem diameter, fresh and dry weights of the herb, number of flower heads/plant, fresh and dry weights of flower heads, essential oil yield, as well as N, P and K% in dried herb while proline content was increased with increasing intervals. On the other hand, in most cases all the studied parameters were increased significantly as a result of spraying plants with either concentration of Amino Suam or Setter-2 compared to control plants. Regarding the effect of interaction between the two studied factors, the results indicate that in most cases, plants irrigated every 4, 8 and 12 days and sprayed with any concentration of bio-stimulators (Amino Suam or Setter-2) had the values for all the studied parameters which were significantly higher than those of control plants. Concerning essential oil composition, α-bisabolol oxide A, α-bisabolol oxide B, farnesene, bisabolone oxide, α-bisabolol and Chamazulene were the six major compounds of Chamomile oil. The highest percent of α-bisabolol oxide A (53.50%) were obtained from plants irrigated every 12 days and sprayed with Setter-2 at concentration of 2000 ppm and the highest percent of α-bisabolol oxide B (16.99%), farnesene (12.55%) and bisabolone oxide (12.03%) were resulted from plants irrigated every 8 days and sprayed with Amino Suam at 1000 ppm, while the highest percent of α-bisabolol (6.36%) and Chamazulene (4.37%) were obtained from plants irrigated every 4 days and sprayed with Amino Suam at 2000 ppm.

Morphological, physiological and biochemical responses to drought stress of Stone pine (Pinus pinea L.) seedlings

In this study, the effect of irrigation intervals (drought stress) on growth, predawn xylem water potential (Ψ w), the osmotic potential at full turgor (Ψπ 100), the osmotic potential at the turgor loss point (Ψπ TLP), osmotic adjustment and osmotic solutes (soluble sugars and proline) of Pinus pinea L. seedlings were examined. An experiment was carried out under greenhouse conditions using four watering treatments (control, 7-, 14- and 21-day irrigation intervals) in the first growth season; from mid-July to early November. Results showed that irrigation interval had significant effect on growth characteristics, Ψ w, water relation parameters, and osmotic solutes. The increasing irrigation interval significantly decreased the seedling height, root collar diameter, root, stem and needle dry weight, number of lateral branches, root percentage, root:shoot ratio and diameter:height ratio. Ψ w and total soluble sugars decreased while proline content increased with the increase of drought stress. The Ψπ 100 and Ψπ TLP significantly decreased in drought-stressed seedlings compared to control (no stress) seedlings. The results suggest that the impact of drought stress increased with the increase of irrigation interval. Therefore, in the drought-stressed P. pinea seedlings were indicated osmotic adjustment by increasing the proline content and decreasing Ψπ 100 and Ψπ TLP during drought stress. Growth decreased under drought stress conditions in P. pinea seedlings.

Effects of Super-Absorbent Polymer Application on Yield and Yield Components of Rapeseed (<i>Brassica napus</i> L.)

Limitation of water resources and its great impact on agricultural and natural resources play a crucial role in the efficiency of water use. Applying super absorbent polymer to the soil may be one of the methods to minimize the stress of weather dryness in arid and semi-arid regions. In order to evaluate the effects of hydrophilic polymer application on yield and water use efficiency of rapeseed plants, an experiment was conducted under field condition in 2012 at the Research Farm of the Faculty of Agriculture, University of Maragheh. Treatments’ factors were: (i) 3 super absorbent polymers (SAP) (Taravat A200) levels of 0 (without application), 75 and 150 kg ha-1 A200 application, (ii) three irrigation levels of 80, 120 and 180 mm evaporation from class A basin in main plots, (iii) two cultivars ʻHyola 401ʼ and ʻRVSʼ in sub plots as factorial split plot combination based on completely randomized block design with three replications. The results showed that in all of the measured traits within the experiment there were significant differences between SAP levels. Furthermore, increasing irrigation interval led to an increase in a thousand seeds’ weight, but decreased seed yield. Increasing water stress raised seed oil percent and infertile silique and subsequently resulted in reduced oil yield. ʻHyola 401ʼ was more susceptible to embryo abortion compared with ʻRVSʼ. As a conclusion of the research, SAP (A200) application in quantities smaller than 75 kg ha-1 may be recommended for rapeseed production under field condition.

Effects of Super-Absorbent Polymer Application on Yield and Yield Components of Rapeseed (<i>Brassica napus</i> L.)

Limitation of water resources and its great impact on agricultural and natural resources play a crucial role in the efficiency of water use. Applying super absorbent polymer to the soil may be one of the methods to minimize the stress of weather dryness in arid and semi-arid regions. In order to evaluate the effects of hydrophilic polymer application on yield and water use efficiency of rapeseed plants, an experiment was conducted under field condition in 2012 at the Research Farm of the Faculty of Agriculture, University of Maragheh. Treatments’ factors were: (i) 3 super absorbent polymers (SAP) (Taravat A200) levels of 0 (without application), 75 and 150 kg ha-1 A200 application, (ii) three irrigation levels of 80, 120 and 180 mm evaporation from class A basin in main plots, (iii) two cultivars ʻHyola 401ʼ and ʻRVSʼ in sub plots as factorial split plot combination based on completely randomized block design with three replications. The results showed that in all of the measured traits within the experiment there were significant differences between SAP levels. Furthermore, increasing irrigation interval led to an increase in a thousand seeds’ weight, but decreased seed yield. Increasing water stress raised seed oil percent and infertile silique and subsequently resulted in reduced oil yield. ʻHyola 401ʼ was more susceptible to embryo abortion compared with ʻRVSʼ. As a conclusion of the research, SAP (A200) application in quantities smaller than 75 kg ha-1 may be recommended for rapeseed production under field condition.

Effect of irrigation intervals and nitrogen fertilization on growth and yield of two maize hybrids

Two field experiments were carried out at the Research Farm of the Faculty of Agriculture, Assiut University, during 2008 and 2009 seasons, to study the effect of three irrigation intervals (15, 25 and 35 days) and three nitrogen fertilization rates (40, 80 and 120 kg/fed.) on the growth and yield of two maize hybrids (S.C. Watania 4 and T.W.C. 310). Increasing irrigation intervals significantly reduces maize growth and yield and its components as well as the percentage of protein and oil ingrains. This reduction in grain yield (76.28 and 63.07%) is due to irrigation every 35 days compared to irrigation every 15 days for the first and second seasons respectively. The two hybrids significantly differed in most of growth characters in both seasons and grain yield and its components in the second one with superiority of S.C. Watani4. Increasing N-rates significantly increased the growth of maize andgrain yieldand its components as well as the percentage of protein and oil in grains. Interaction between irrigation intervals and N-rates significantly affected grain yield/fed. in the first season and that highest yield, when irrigation every 15 days and application of 120 kg N/fed.