Increasing Irrigation Intervals Research Articles

Enhancing cotton sustainability: Multi-factorial intercropping, irrigation, and weed effects on productivity, quality and physiology

Drought stress and weed infestation are significant factors that significantly decrease cotton yield. Increasing the variety of plants within a cotton field ecosystem can strengthen its stability and protect it from susceptibility to both biotic and abiotic pressures. In this two-year experiment (2021 and 2022), the effects of intercropping systems (four growth conditions including mono- and inter-cropped cotton varieties Golestan and Hekmat with Nepeta crispa and dragon's head (Lallemantia iberica)), irrigation (three intervals of 3, 6, and 9 days), and weed competition (weed-free and weedy plots) on the agronomic performance, physiological characteristics, and seed quality of cotton in a semi-arid region of Iran were studied. In 2021, the volume of irrigation water applied was 9873, 6100, and 4650 m3 ha−1 for irrigation intervals of 3, 6, and 9 days, respectively. In 2022, the volumes were 9071, 5605, and 4272 m3 ha−1 for the corresponding irrigation intervals. Over two years, Xanthium strumarium, Amaranthus retroflexus, and Portulaca oleracea were the dominant weed species. Weeds had the most significant impact on total dry weight; weed control increased plant vigor and growth, ranging from 1.4 to 2.3 times, while weed impact on cottonseed yield ranged from 18% to 96% reduction. Increasing irrigation intervals resulted in reductions in various parameters, with decreases of 39%–80% in total dry weight, 34%–57% in cottonseed yield, and 48%–72% in lint yield. The harvest indices for seed cotton, cottonseed, and lint ranged from 35.3% to 56.5%, 18.3%–35.0%, and 15.4%–20.5%, respectively. Weeds were responsible for a 17% decrease in the 1000-seed weight. As the irrigation intervals increased from 3 days to 6 days and 9 days, the number of bolls per plant decreased by 19%–85%. Extending the irrigation interval from 3 days to 6 days and 9 days resulted in a substantial decrease in the photosynthetic rate, ranging from 42% to 92%. Mono-cropped Golestan performed well under unstressed conditions such as 3-day interval irrigation and weed-free conditions. On the other hand, intercropped Hekmat demonstrated better resilience to both moisture and weed stresses. The LER (Land equivalent ratio) indices of both intercropping systems were generally favorable, indicating higher productivity compared to sole cropping. The intercropping systems consistently showed the highest LER indices under weedy conditions, highlighting the significance of intercropping as a valuable method in integrated weed management.

Evaluation of growth, yield and elements uptake of grafted tomatoes on several Solanaceous rootstocks exposed to deficit irrigation

A greenhouse experiment was carried out using seven Solanaceous species as rootstocks. Tomato plants were grafted on these rootstocks and after the healing and acclimatization period, were transferred to a soil-based greenhouse and exposed to three irrigation frequencies (3-day interval as control, 6-day and 9-day interval as moderate and severe drought stress) for four months. The results showed that shoot and root dry weight, daily dry matter production and yield were decreased with increasing irrigation intervals. At the same time, harvesting index was not affected by irrigation treatments in any of the grafting combinations. The concentration of N, Ca and Mg in leaf and root tissues were not influenced by irrigation intervals while P was increased in both leaf and root with increasing irrigation intervals and K was increased in leaf and decreased in root tissue. Leaf relative water content and electrolyte leakage were influenced by irrigation treatment. The applied rootstocks had a prominent effect on growth, yield, P and K concentration in leaf and root and reduction of leaf electrolyte leakage. Cherry tomato (Solanum lycopersicum var. cerasiforme) was superior to other rootstocks in terms of measured parameters, followed by Galapagus and Emperador. The positive role of these rootstocks in the mitigation of adverse effects of drought may be related to their vigorous root system. It is concluded that grafting as a healthy technique, since no chemical treatment is required, may increase the resistance of tomato plants against drought stress depending on the genotype of the rootstock.

Mitigating Osmotic Stress and Enhancing Developmental Productivity Processes in Cotton through Integrative Use of Vermicompost and Cyanobacteria.

There is an urgent demand for biostimulant amendments that can sustainably alleviate osmotic stress. However, limited information is available about the integrated application of vermicompost and a cyanobacteria extract on cotton plants. In 2020 and 2021, two field experiments were carried out in which twelve combinations of three irrigation intervals were employed every 14 days (Irrig.14), 21 days (Irrig.21), and 28 days (Irrig.28) along with four amendment treatments (a control, vermicompost, cyanobacteria extract, and combination of vermicompost + cyanobacteria extract) in salt-affected soil. The integrative use of vermicompost and a cyanobacteria extract resulted in an observed improvement in the physicochemical attributes; non-enzymatic antioxidants (free amino acids, proline, total soluble sugars, and phenolics); and antioxidant enzyme activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) and a decrease in the levels of oxidative damage indicators (H2O2 and MDA). Significant augmentation in the content of chlorophyll a and b, carotenoid concentration, relative water content, stomatal conductance, and K+ was also observed. In conjunction with these findings, noticeable decreases in the content of Na+ and hydrogen peroxide (H2O2) and the degree of lipid peroxidation (MDA) proved the efficacy of this technique. Consequently, the highest cotton yield and productivity as well as fiber quality were achieved when vermicompost and a cyanobacteria extract were used together under increasing irrigation intervals in salt-affected soil. In conclusion, the integrated application of vermicompost and a cyanobacteria extract can be helpful for obtaining higher cotton productivity and fiber quality compared with the studied control and the individual applications of the vermicompost or the cyanobacteria extract under increasing irrigation intervals within salt-affected soil. Additionally, it can also help alleviate the harmful impact of these abiotic stresses.

Response of Ruellia simplex plants grown under water intervals and anti-transpirant treatments

Ruellia is herbaceous perennials are described as colorful groundcovers and it is very popular landscape plant cuttings of Ruellia plant were planted in pots. In the National Research Centre's greenhouse in Dokki, Giza, Egypt. A pot experiment was conducted in July 2020 and 2022 to examine the influence of KCl spraying and duration of irrigation on Ruellia plant growth and chemical contents. The current study compares the growth parameters of plants treated with KCl in three sprays at concentrations (0, 50 and 100 ppm) and water regime (3, 6 and 9 days) to those of control plants. However, increasing irrigation intervals for Ruellia plants there had no significant on growth parameters (plant height, branches number, root length, stem diameter and fresh and dry weight of shoots), while increasing irrigation intervals from 3days up to 9 days, increased flower number and delayed flowering. In addition, it is evident that N% was the highest by increasing irrigation intervals up to 9 days while P% showed a constant content, however the lower N% was recorded with the low irrigation intervals. Carbohydrate % as well as protein and photosynthetic pigments saved the same trend percentage. It can be concluded that, the increasing KCl concentration level up to 100 ppm caused an increase in previous mentioned vegetative growth parameters, flower number, flowering date, and chemical constituents (total chlorophyll, carbohydrate, protein%, carotenoids and mineral elements (N, P and K) concentrations compared with control and other KCl treatments. The purpose of this study is to learn more about the effects of KCl and water intervals on plant development and chemical components.

Enhancement growth of Swietenia Mahogany seedlings under different irrigation intervals by foliar application of basil leaves extract

Drought is a global problem that many countries suffer from, as a result of climate change. Swietenia mahogany tree is grown as an ornamental and timber tree and its wood is used in shipbuilding and furniture manufacturing. Therefore, the goal is to use this type of plant for its multiple uses, while reducing the quantities of water consumed for its growth to cope with the drought conditions by using basil leaves extract as natural extract and eco-friendly, it is noticed that all vegetative growth parameters and photosynthetic pigments decreased by increasing irrigation intervals, the rest chemical constituents were increased by increasing irrigation intervals except total sugar content which showed the highest value at irrigation every 7 days. Treating the seedlings with BLE at 10% enhanced all vegetative growth parameters and photosynthetic pigments and reduce all oxidative markers and so antioxidant compounds, it was concluded that BLE at 10% enhanced the tolerance of S. mahogany seedlings under all irrigation levels. The irrigation every 5 days showed preferable results followed by irrigation every 7 days.

Lemongrass Growth, Essential Oil, and Active Substances as Affected by Water Deficit

Environmental stress has a major influence on the growth and quality of medicinal plants. More than half of the agricultural land worldwide suffers from a lack of water. In this study, we estimated the effect of different irrigation intervals on growth, yield, and essential oil content as well as their effect on the main compounds of the essential oil of lemongrass, Cymbopogon citratus. The major objective was to test how much irrigation consumption can be lowered without a significant impact on yield and quality properties. Water deficit led to significant decreases in growth characteristics including the number of tillers as well as fresh and dry herb yield. In addition, the relative leaf greenness decreased under water deficit, especially in plants irrigated every 20 days. In contrast, proline content increased with increasing water deficit, especially in plants irrigated every 15 and 20 days. Essential oil percentage also increased under a water deficit condition, and the highest essential oil percentage was observed in plants irrigated every 15 and 20 days. However, the yield of essential oil per plant significantly decreased due to decreasing the herb yield. GC-MS analysis identified 31 compounds, mainly geranial and neral. Geranial and neral percentage decreased under a water deficit of 10-day irrigation intervals but increased with increasing the water deficit severity at irrigation intervals of 15 and 20 days. These results suggest that the lemongrass plant was sensitive to drought. Nevertheless, the quality represented by essential oil percentage and the main active substances improved with prolonging the irrigation intervals. This study recommends increasing irrigation intervals to 10 days to maintain small decreases in the yield with higher quality. In addition, it is recommended to conduct more studies to improve the growth of lemongrass under water shortage conditions.

Correction to: Nano-Silicon Complexes Enhance Growth, Yield, Water Relations and Mineral Composition in Tanacetum parthenium under Water Deficit Stress

Developing methods and approaches for preserving water relations, plant growth and productivity are essential under water deficit conditions. New nano-silicon complexes were synthesized (glycine nano-silicon, glutamine nano-silicon and histidine nano-silicon) to evaluate their foliar application in different concentrations (0, 1.5 and 3.0 mM) on growth, essential oil yield, water relations, and mineral composition of field grown feverfew (Tanacetum parthenium L.) under drought. Drought stress was imposed by different irrigation intervals (4, 8 and 12 days). By increasing irrigation interval, leaf relative water content and leaf water potential were declined which decreased biomass, leaf area, flower formation, essential oil production and health of the plant. Potassium and organic osmolytes accumulation under moderate drought stress alleviated the adverse effects water deficit condition. This was mainly due to proline and potassium accumulation in the plants’ leaves. Although accumulation of soluble carbohydrates also was observed in the drought stressed plants, it was found to be a passive response to plant growth inhibition under drought. Moreover, drought stress decreased plant phosphorous content, but had no significant effect on plant nitrogen content. Foliar application of nano-silicon by improving the plant’s water content and phosphorus absorption, recovered the plants’ health and growth under moderate and severe drought conditions. In this regard, no significant differences were observed between 1.5 and 3.0 mM nano-silicon treatments. However, glycine nano-silicon treated plants represented higher drought tolerance (higher dry mass, leaf area, number and greenness) than the other complexes. Accordingly, foliar application of 1.5 mM glycine nano silicon for mitigating adverse effects of drought stress on feverfew was recommended.

Influence of irrigation intervals on dry matter yield, concentration of crude protein, calcium and phosphorus in Lablab purpureus and Sorghum almum fodder in the sudan savanna zone of Nigeria

Irrigation trials were conducted in the late dry season (March to June) with Lublab (Lablab purpureus) and Columbus grass (Sorghum almum) in the Sudan savanna of Nigeria. The objective of this study was to determine the dry matter yield (IDM/ha), crude protein (CP), calcium (Ca) and phosphorus(P) in dual-purpose lablab bean and Sorghum almum at 3 irrigation schedules (5, 7 and 10 days irrigation interval). The results obtained showed dry matter yield in lablab increased (P<0.05) and varied from 1.7 to 11.7 IDM/ha. Calcium and P concentrations differed significantly (P<0.05). Mean CP for the lablab was 15.57%. Dry matter yield obtained for Sorghum almum varied (P<0.05) from 11.07 to 19.6 tDM/ha. Concentration of CP and Ca rose and declined thereafter with a mean concentration of 9.86% for CP und 0.08% for Ca while P declined consistently (P<0.05). Intervals of irrigation days had a relationship (P<0.05) with DM/ha, Ca and P in lablab. The increasing trend in foruye yield with increased irrigation interval showed optimum irrigation interval was not attained. It is therefore recommended that longer irrigation intervals be tried to determine the optimum irrigation interval after which forage yield would be depressed due to moisture stress. From the results of the present study Sorghum almum and lablab would be grown successfully at a 10-day irrigation interval.

Uticaj razlicitih doza iivinskog stajnjaka i navodnjavanja na rast i prinos bamije (Abelmoschus esculenfus L.)

The use of organic addition has been found to be an environmentally beneficial method for enhancing quality of crops with good soil quality. Similarly, selection of suitable irrigation period is an important factor for optimum crop production. A study was conducted to evaluate the effects of chicken manure and irrigation interval on the development and production of okra in a greenhouse. The poultry manure was applied to 5 kg soil at three different rates, namely: 20 t ha-1 (T1), 40 t ha-1 (T2), and 60 t ha-1 (T3), and the fourth group without poultry manure treatment were set up as the control. Four levels of irrigation intervals (3, 6, 9 and 12 days) were selected for the study. Plant height, number of leaves, leaf area (cm2), and stem diameter were all assessed as growth metrics. Leaf fresh weight, leaf dry weight, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, and total plant dry weight were the yield characteristics that were measured. The findings indicated that increasing poultry manure rates enhanced the examined growth and yield parameters, but increasing irrigation intervals decreased the studied growth and yield characteristics of Abelmoschus esculentus. The interplay between chicken manure and irrigation intervals, on the other hand, had no significant effect on leaf area and stem diameter. Finally, the application of 60 t ha-1 poultry manure and a three-day watering interval boosted the development of Abelmoschus esculentus. Keywords: Abelmoschus esculentus, irrigation, okra, poultry manure, yield

Effect of Zeolite, Potassium Fertilizer and Irrigation Interval on Yield and Quality of Sugar Beet in Sandy Soil

Two field experiments were carried out at Al-Hussein Agricultural Society Farm, Giza Governorate, Egypt, during 2017/2018 and 2018/2019 growing seasons to study the effect of three irrigation intervals [every 3 days (the conventional practice), 5 and 7 days], two levels of zeolite (zero and 500 kg/fed) and four levels of potassium fertilizer the first one in the form of potassium sulphate as a control [100% of the recommended K-dose], which was applied to the soil and three foliar doses of nano- potassium (500, 1000 and 1500 mg /l) on yield and quality of sugar beet grown under drip irrigation system in a sandy soil. The treatments were arranged in a complete block design in a split-split plot with three replications. Results revealed that increasing irrigation interval from 3 up to 7 days significantly reduced biochemical and physiological traits and root and sugar yields/fed. Soil application of zeolite achieved the highest values of all the parameters studied as compared to the untreated soil. Spraying beets with 1500 mg /l of nano-K gave the same trend of the recommended K-dose. Water use efficiency (WUE) for sugar yield increased with decreasing the amounts of applied irrigation water. Under conditions of the present work, adding 500 kg of zeolite/fed to the sandy soil, spraying beets with 1500 mg l-1 as nano-K fertilizer and irrigating the crop every 5 days using drip irrigation can be recommended to get the highest root and sugar yields as well as to save water and increasing water use efficiency.

Irrigation scheduling for green beans grown in clay loam soil under a drip irrigation system

An experimental field trial was conducted at El-Ayat, El-Giza Governorate, Egypt (latitude 30°11´13"N, longitude 31°41´38"E, and mean altitude 74 m above sea level) during the growing season of 2017 and 2018. The study aimed to assess the suitable irrigation interval and applied water volume for drip-irrigated green beans, based on water production functions and water use–yield relationships. The field trial was arranged in a split-plot design with 3 irrigation intervals (F1, F2 and F3 irrigation events, once every 1, 2 and 3 days, respectively) and 3 irrigation regimes (I1: 1.00, I2: 0.80, and I3: 0.60 of the crop evapotranspiration, ETc). The results showed that the yield and water use efficiency (WUE) increased with increasing irrigation interval. Maximum and minimum yield of 12 030 and 4 879 kg∙ha-1 were obtained in F1I2 and F3I3 treatment, respectively, in the winter season of 2017, and were 12 364 and 4 678 kg∙ha-1 for the corresponding treatments in the winter season of 2018. WUE ranged from 56.55 kg∙ha-1∙mm-1 in F1I2 to 23.80 kg∙ha-1∙mm-1 in F3I3. Plant growth parameters were significantly affected by the irrigation schedule. The highest plant growth parameters were obtained under F1 and F2. The seasonal yield response factors (ky) were 0.845 and 0.856 in 2017 and 2018, respectively. The relationship between yield and seasonal crop ET was best explained by a power function for all irrigation schedules for both growing seasons. It is recommended that the F1I2 irrigation treatment is the suitable one for green beans grown under field conditions, in order to achieve the highest yield and WUE.

Impact of drought stress and stress modifiers on water use efficiency, membrane lipidation indices, and water relationship indices of pot marigold (Calendula officinalis L.)

This study was conducted as a factorial layout based on completely randomized design in three replications in the 2018. The experimental factors included irrigation intervals with 4 levels (3, 6, 9, and 12 days) and drought stress modifiers at four levels (control (non-spraying), spraying with salicylic acid (2 mM), Glycine betaine (5 mM), and zinc sulfate (5 g L−1). The results indicated that the effect of different levels of drought stress and stress modifiers on yield, water use efficiency, membrane lipidation indices, and water relationship indices were significant. The highest water use efficiency based on dry yield (WUEDY) (2.33 kg m−3) and water use efficiency based on essential oil yield (WUEEOY) (0.22 kg m−3) were obtained from irrigation intervals of three days. With increasing irrigation interval from three days to 12 days, dry yield, leaf water content, WUEEOY, cellular membrane stability (CMS), membrane stability index (MSI), total chlorophyll, chlorophyll index, canopy temperature depression (CTD), and relative water content decreased. However, injury index (I), water saturation deficit (WSD), osmotic potential (OP), electrolyte leakage (EL), essential oil percentage, and leaf temperature increased significantly. It seems that at all levels of irrigation, spraying with glycine betaine compared to other modifiers was more effective in increasing WUEDY, WUEEOY, CMS, MSI, total chlorophyll and relative water content, and decrease in I and WSD and EL. Based on the findings, it can be stated that with increasing the irrigation intervals, quantitative and qualitative yields of the pot marigold plant are reduced. The application of drought stress modifiers can reduce the effects of drought stress on this plant, thereby raising WUEDY and WUEEOY.

Effect of planting methods and irrigation intervals on productivity of some bread wheat cultivars

A field experiment was carried out at Experimental Farm, in Al- kalahyn, Al- Hajer village, Qeft, Qena governorate, Egypt during 2017/2018 and 2018/2019 seasons, to evaluate of three planting methods (Drilling, broadcasting and furrows) and three irrigation intervals (21 , 28 and 35 days) on productivity of three wheat cultivars ( Sids 12 –Misr 2 and Giza 168 ). The results showed that exposing wheat plants to drought stress by increasing irrigation intervals significantly decrease (1000-grain weight, grains spike weight, number of spikes/m2, grain yield (ardab/fed) (argab = 150 Kg, fed= feddan= 42002 m² = 0.420 hectares = 1.037 acres), straw yield (ton/fed) and protein %). Irrigation intervals showed highly significant difference in for all characters studies. The highest value resulted from application irrigation intervals at 21 day compare with the other irrigation intervals. Planting methods significantly affected by all a previous characters. The highest value for all studies characters resulted from using drilling method. There were highly significant differences among wheat cultivars for all characters under study. The wheat cultivar sids-12 gave of the highest values of all traits compared to the other wheat cultivars used in both seasons.

Nano-Silicon Complexes Enhance Growth, Yield, Water Relations and Mineral Composition in Tanacetum parthenium under Water Deficit Stress

Developing methods and approaches for preserving water relations, plant growth and productivity are essential under water deficit conditions. New nano-silicon complexes were synthesized (glycine nano-silicon, glutamine nano-silicon and histidine nano-silicon) to evaluate their foliar application in different concentrations (0, 1.5 and 3.0 mM) on growth, essential oil yield, water relations, and mineral composition of field grown feverfew (Tanacetum parthenium L.) under drought. Drought stress was imposed by different irrigation intervals (4, 8 and 12 days). By increasing irrigation interval, leaf relative water content and leaf water potential were declined which decreased biomass, leaf area, flower formation, essential oil production and health of the plant. Potassium and organic osmolytes accumulation under moderate drought stress alleviated the adverse effects water deficit condition. This was mainly due to proline and potassium accumulation in the plants’ leaves. Although accumulation of soluble carbohydrates also was observed in the drought stressed plants, it was found to be a passive response to plant growth inhibition under drought. Moreover, drought stress decreased plant phosphorous content, but had no significant effect on plant nitrogen content. Foliar application of nano-silicon by improving the plant’s water content and phosphorus absorption, recovered the plants’ health and growth under moderate and severe drought conditions. In this regard, no significant differences were observed between 1.5 and 3.0 mM nano-silicon treatments. However, glycine nano-silicon treated plants represented higher drought tolerance (higher dry mass, leaf area, number and greenness) than the other complexes. Accordingly, foliar application of 1.5 mM glycine nano silicon for mitigating adverse effects of drought stress on feverfew was recommended.

Effect of Irrigation Intervals on Growth, Productivity and Quality of Some Yellow Maize Genotypes

TWO FIELD experiments were done at Experimental Farm, Faculty of Agriculture, Menoufia University, Shebin El- Kom, Egypt, during 2018 and 2019 seasons to study the effect of 3 irrigation intervals, i.e., irrigation every 12 (I1), 17 (I2) and 22 days (I3) on growth, productivity and quality of 6 yellow maize genotypes (G), i.e., S.C 178, S.C 176, S.C 168, T.W.C 368, T.W.C 360 and T.W.C 352. The results could be summarized as follows:1- Increasing irrigation intervals from 12 up to 17 and 22 days significantly decreased number and area of leaves and leaves, stem and total dry weight/plant, total chlorophyll, relative water content (RWC), plant height, length and diameter of ear, number and weight of grains/ear, 100 grain weight as well as grain, stover and biological yields/fed, protein and oil % and yields/fed, but significantly increased proline content in leaves in both seasons.2- S.C 168 G surpassed the other genotypes in area and dry weight of leaves/plant, grain yield/fed, crop and harvest indices as well as protein yield/fed. T.W.C 368 G was superior in stem and total dry weight/plant, plant height, ear diameter, no.of grains/ear,100-grain weight as well as stover and biological yields/fed. However, S.C 168 G and T.W.C 368 G recorded the best values of RWC, no.of ears/plant, grain weight/ear, protein% and oil yield/fed as compared with the other genotypes. The highest significant values of proline content and no.of leaves/plant were obtained by T.W.C 352 G and T.W.C 360 G, respectively in both seasons.3- Maize genotypes S.C 168 as well as T.W.C 360 and T.W.C 352 under I2 and T.W.C 368 under either I2 or I3 had the lowest values of relative yield reduction and drought suS.Ceptibility index (< 1), indicating that those genotypes are relatively drought tolerant genotypes compared to other tested genotypes in our experiment condition.

Impact of Irrigation Methods, Irrigation Scheduling and Mulching on Seed Yield and Water Productivity of Chickpea (Cicer arietinum)

An experiment was conducted to test the efficacy of irrigation methods and mulching in seed production of chickpea. Irrigation methods included drip with mulch (DM), drip without mulch (DNM) and check basin (CB) irrigation. Drip irrigation was scheduled at 1-day, 2-day and 7 days interval, while farmers’ practice of check basin irrigation at 7-day interval was considered as control. Plant parameters like height, horizontal spread, dry matter, root length and root spread, and number of pods were significantly influenced by irrigation levels and mulch. Seed yield of 17.7 and 16.8 q/ha was recorded for DM having 1-day and 2-day interval, respectively, which was about 82 and 73% higher over the control. The harvest index increased with increasing irrigation interval and was highest (57.4) under treatments with longer irrigation interval (DM7, DNM7 and CB7). Drip irrigation at 1-day and 2-day interval recorded the water productivities of 0.54 and 0.52 kg/m3, respectively as against 0.30 kg/m3 recorded in farmers practice. Polythene mulch with drip irrigation at 2-day irrigation interval is recommended for improving the yields and water productivity of chickpea cultivated under eastern plateau and hill region of India.

Quinoa: A super or pseudo-super crop? Evidences from evapotranspiration, root growth, crop coefficients, and water productivity in a hot and semi-arid area under three planting densities

Quinoa is well known for its great ability to tolerate water stress. However, very little information is available about its potential growth under full irrigation particularly in hot and semi-arid regions. In this experiment, a newly-released quinoa (cv. Q5) bred for hot and dry regions was grown under three planting densities (PDs) of 150,000, 185,000, and 270,000 in the drainable lysimeters, south of Iran. The highest and lowest grain yields were observed in the middle and low PDs of 3.65 Mg ha−1 and 2.86 Mg ha−1, respectively. Quinoa showed very high crop evapotranspiration (ETc) and transpiration (T) rates. ETc and T varied in the range of 1448–1687 mm, and 777–1228 mm among the PDs, respectively. These high values resulted in high single crop coefficients (Kc) that overall varied between around 1 and 2.4 during the growing season. The basal crop coefficient (Kcb) of the dual Kc (Kc = Kcb + Ke) reached about 1.9 and 1.2 in the high and low PDs, respectively, indicating high transpiration capacity. The main reasons of high Kc and Kcb were high soil evaporation rate due to very frequent irrigations of 3–4 days and soil wetting, and the prevailing regional sensible heat advection that increased transpiration. It was concluded that quinoa has a specific physiological systems that transpire continually for allowing better leaf cooling at high temperature, which results in high water use. Moreover, a vigorous root system that extended down to 1.2 m with high root length densities in the deep layers (RLD > 1 cm cm-3) helped quinoa to supply the water use. This extensive root system down to 1.2 m could help to increase irrigation interval and reducing soil evaporation. However, the effect of PD on the root length and root mass was mainly observed in the top 40 cm, below which its effect diminished and root length and root mass were nearly identical among the PDs. Overall, it is concluded that quinoa Q5 is a super crop that not only can tolerate water stress, but also can potentially grow well and produce acceptable grain yield in the hot and semi-arid areas. Adapting appropriate PD and irrigation management such as drip irrigation (surface and subsurface), mulching, increasing irrigation interval attributed to the deep rooting system, and water-saving irrigation managements would substantially reduce soil evaporation and increase water productivity.

Influence of Super Absorbent Polymers (Saps) on Irrigation Interval and Growth of Black Pepper (&lt;i&gt;Piper Nigrum&lt;/i&gt; L.) in Nursery Management

Drought stress is one of the most adverse limitations of local black pepper production in Dry and Intermediate zones of Sri Lanka. Application of Super Absorbent Polymers (SAPs) is hypothesized to result in the optimised use of water resources in these regions. A study was undertaken to examine the effect of different levels of irrigation intervals and different level of SAPs and then to find out the best treatment combination for growth of black pepper plants under nursery management. The experiment was conducted at Intercropping and Betel Research Station, Narammala. GK49 was the selected variety and Zeba (commercial name) was the selected SAP type. The experiment was carried out following a factorial layout based on Complete Random Design (CRD) with three replicates. The factors were three levels of irrigation intervals as 4, 8 and 10 days (T1 to T3) and four levels of SAPs as no Zeba, 1g, 1.5g and 2g of Zeba (L1 to L4). Plant growth parameters were measured at two weeks interval and all the parameters were analysed by anova using SAS software. Statistical analysis had shown that there were significant effects (P<0.05) of main factors and their interactions on plant parameters. Plant parameters were decreased with decreased Zeba amount and increased irrigation interval. In this study 2g of Zeba with 4 and 8 days irrigation interval (L4T1, L4T2) and 1.5g of Zeba with 4 days of irrigation interval (L3T1) treatments were the better treatments. However, considering the cost effectiveness 2g of Zeba with 8 days irrigation interval (L4T2) treatment is recommended as the best treatment for increasing plant performances and decreasing water stress conditions to the plant. Therefore, the results of this study showed that SAPs can store and absorb a considerable amount of water and reduce unfavourable effects of water shortage on black pepper plants in nursery management.

Fortified Groundnut Shells as a Soil Amendment for Improved Productivity in Oilseed Based Cropping System of Semi-arid Tropics (SAT) India

Soil degradation in semi-arid regions is alarming due to changed climate impacting the rainfall patterns and temperature affecting soil physico-biological properties adversely. In India, cattle shed bedding technology (CSBT) using crop residues is cheaper, easy-to-use residue recycling method for small holders in semi-arid regions. The present research work was carried out with a specific objective of soil improvement leading to resilience of land use system using indigenously available fortified crop residue for enhanced crop and cropping system yields under both rainy and post rainy conditions in semi-arid tropics of India. Thus, a study was conducted for 2 years (2013–2014 and 2014–2015) in the farmers fields with treatments having various fortifications like bedding material with groundnut shell and its manure, compost over existing practice among farmers on rainfed groundnut-fallow (L-F), castor-groundnut (NL-L) and groundnut–groundnut (L–L) oilseed based cropping systems. These systems were evaluated for soil quality parameters, productivity, fertility, soil moisture retention, compaction, crop land utilization and economics. In different cropping systems, use of fortified groundnut shell @ 16.3–22.6 t ha−1 year−1 was able to recoup the soil nutrient losses (183.0 kg N, 6.1 kg P, 227.0 kg K and 0.3 kg OC ha−1 year−1) closely followed by compost and distantly by inorganics application with additional benefit of enhanced crop yields by 20.2–33.1% during subsequent rainy and 20.0–25.0% during post-rainy season, improved available water content (10.7–20.3%) and increased irrigation interval by 3–5 days in NL-L and L–L system. Hence, the principle of fortifying crop residues through CSBT could be utilized globally in similar agro-ecological regions for addressing soil degradation and effective crop residue utilization for small and marginal landholders farmers.

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.