Drainage Lysimeters Research Articles

Water requirements of cowpea (Vigna unguiculata (L.) Walp.). calculated with the cultivation coefficient using drainage lysimeter

The objective is to estimate the water needs of the cowpea ( Vigna unguiculata L.) var. INIAP-463 from the culture coefficient using drainage lysimeter. It was carried out in the months of January to April 2018, three plots of 25m2 were implemented, and drainage lysimeters were located in the center of them. The plots were placed near the meteorological station located at the Pontificia Universidad Católica del Ecuador Sede Manabí. The data of the climatological variables were used to estimate the reference evapotranspiration (ETo) by the Penman Monteith method modified by the FAO. Daily monitoring of the drainage sheet of the lysimeter and soil moisture present in it. The irrigation sheet was applied daily, based on the daily ETo and the rainfall of the place. The calculation of the Kc was carried out for each stage of the culture, determining the ratio between the evapotranspiration of the culture (ETc) and ETo. The Kc values ​​for the bean were: first stage with a duration of 15 days a Kc of 0.45 was obtained, second stage 20 days a Kc of 0.88, third stage 25 days a Kc of 1.28, fourth stage 20 days a Kc of 0.70. The water requirement of the cowpea was greater in the third stage with 114.33 mm and the one with the lowest consumption was the first stage with 20.46, the total water need was 254 mm for 80 days after transplantation. The results found allow us to conclude that the water needs of the cowpea var. INIAP-463 were higher in the third stage of cultivation due to the presence of organs of vegetative reproduction and abundant leaf area.

Biochar impacts on nutrient dynamics in a subtropical grassland soil: 1. Nitrogen and phosphorus leaching.

Despite the numerous benefits of biosolids, concerns over nutrient losses restrict the extent to which biosolids can be beneficially reused. We evaluated the effectiveness ofbiochar in controlling the lability of nutrients in agriculturalland. This study was designed to investigate the potential impacts of co-applying biochar with biosolids or inorganic fertilizer on N and P leaching losses. A companion paper focuses on greenhouse gas responses. Nutrients were surface applied as biosolids (aerobically digested Class B) and inorganic fertilizer (ammonium nitrate and triple superphosphate) to an established perennial pasture at equivalent annual rates typical of field practices. Biochar was applied at an annual rate of 20 Mg ha-1 . Leachate N and P were monitored using passive-capillary drainage lysimeters. Results demonstrated significant temporal variability in leachate N and P, with larger pulses generally occurring during periods of high water table levels or after intensive rainfall. Inorganic fertilizer generally resulted in greater leachate N and P losses than biosolids. No differences in leachate N and P losses between biosolids and control were observed. Approximately 1% of applied N was lost via leaching from biosolids treatments vs. 16% for inorganic fertilizer. Regardless of the P source, negligible (0.1-0.2% of applied P), cumulative P leaching occurred during the 3-yr study. Biochar had no effect on P leaching but reduced N leaching from treatments receiving inorganic fertilizer by 60%. Prudent nutrient management is possible even on biosolids-amended Spodosols with high water tables.

Nitrate leaching losses mitigated with intercropping of deep-rooted and shallow-rooted plants

Nitrate (NO3−) leaching has been recognized as a worldwide problem, and NO3− is a major pollutant in ground and surface waters. The gradual leaching of residual NO3− into soil layers below the root zone is the main way of nitrogen (N) loss in cropping systems. The interception of NO3− by subsurface roots is crucial for crops or vegetables to utilize N. However, few studies were focused on the mechanisms of NO3− leaching under intercropping of deep-rooted and shallow-rooted plants. In a greenhouse production system, we selected deep-rooted and shallow-rooted plants for single-season intercropping planting experiments (MP, monoculture of pepper; IPA, intercropping of pepper and alfalfa; IPM, intercropping of pepper and maize). Plants were grown in core drainage lysimeters for 4 months, and leachate was collected by soil solution samplers. The results revealed N transformations between monoculture and intercropping systems by comparing NO3− leaching, N use efficiency, and microbes involved in nitrification. NO3− accumulation mainly occurred in 25–40-cm soil layer, which was affected by root morphology. Compared with monoculture, intercropping reduced NO3− leaching, in particular, pepper/maize intercropping significantly reduced NO3− leaching losses. In deep soil layers, roots of alfalfa and maize were more developed than those of the other crops, which made this corresponding intercropping system more effective in absorbing N in the subsoil. N uptakes of pepper/alfalfa intercropping and pepper/maize intercropping were 19% and 28% higher than that from the monoculture, respectively. Ammonia oxidizing bacteria (AOB) were significantly stimulated with planting especial in the topsoil, while ammonia oxidizing archaea (AOA) decreased with planting along the soil profile. These results indicated that lush plant roots immobilized N from the deep soil and thus improved N use efficiency and reduced NO3− leaching in the deep-rooted and shallow-rooted intercropping system. Intercropping of shallow-rooted pepper with deep-rooted alfalfa can enhance root nutrient absorption in deep soil layers, increasing N use efficiency and thus reducing NO3− leaching. The nitrification process in the intercropped soil was mainly regulated by AOB.

Utility of stabilized nitrogen fertilizers to reduce nitrate leaching under optimal management practices

AbstractBackground: The inadequate application of nitrogen (N) to crops has increased the reactive N in the atmosphere and in the surface and ground waters. Stabilized N‐fertilizers with nitrification (NI) and urease (UI) inhibitors have been proposed to reduce these environmental problems without affecting or even increasing crop productivity.Aim: The objective of this study was to evaluate, in a maize–maize–wheat rotation, if the use of the NI 3,4‐dimethylpyrazole phosphate (DMPP) and the UIs N‐(n‐butyl) thiophosphoric triamide (NBPT) and monocarbamide dihydrogen sulfate (MCDHS) reduces N leaching without compromising yield under optimal management of N and water.Methods: The experiment was conducted in 24 drainage lysimeters with two soil types with contrasting water holding capacity under Mediterranean irrigated conditions. The fertilizer treatments were urea, urea with DMPP, urea with NBPT, and urea with MCDHS. For the maize crop, conventional fertilizer application was split into 6‐ and 13‐leaf stages, whereas stabilized fertilizers were applied as a single application at the 6‐leaf stage. All fertilizer treatments were applied at late tillering in the wheat crop.Results: The soil mineral N was measured at the beginning and the end of each crop season, but no differences were found among fertilizer treatments. Differences in the volume of water drained or the cumulative mass of nitrate depending on the fertilizer were not significant (three‐year treatment average of 200 L m−2 and 22 kg N ha−1 in the Deep soil, and 334 L m−2 and 40 kg N ha−1 in the Shallow type, respectively). No consistent significant differences were found in agronomic parameters (chlorophyll measurements, yield, and total N uptake) between the fertilizer treatments.Conclusion: Based on the results, the use of stabilized N‐fertilizer could be recommended to reduce the number of N applications in maize without compromising grain yield but with no advantages to reduce nitrate‐leaching losses if N rates are managed properly under efficient irrigation management practices.

Mitigation of the effect of secondary salinization by micro soil conditioning

This research has the general goal to meet the customization of agriculture in small scale farming. We are developing a technique using micro doses of soil conditioners and organic material applied in the root zone of vegetable crops. We expected to change the physical and chemical properties of the affected soil, which has been irrigated with salty water. Two different soil conditioners were tested. A lysimeter experiment including 8 simple drainage lysimeters was set up in the Research Institute of Karcag IAREF University of Debrecen in 2017. The main goal was to study the effect of different soil conditioners on the soil endangered by secondary salinization induced by irrigation with saline water. In order to compare the difference between the treatments, we collected soil samples, water samples, and determined the yields. Chili pepper (Capsicum annuum) was used as an indicator crop during one specific agricultural season. The technique called micro soil conditioning is rational because several reasons. The roles of the technique are various, for example it can serve as a source of carbon or a container for soil amendments and can minimize evaporation. We found this technique not to interfere with the chemical reaction or the interaction with the plants. However, the micro doses of soil amendments had the role to minimize the risk of soil degradation and do not significantly influence soil respiration. In addition, by improving soil properties, soil conditioning increases the leaching of the excess of salts from the root zone. In fact, this technique can decrease the cost of the inputs and improves the production of vegetables, and at the same time mitigates the effect of secondary salinization.

Water status, cell damage and gas exchanges in West Indian cherry (Malpighia emarginata) under salt stress and nitrogen fertilization

This study was conducted to evaluate water status, cell damage and gas exchanges of West Indian cherry grown under saline water irrigation and nitrogen (N) fertilization in the post-grafting stage. The experiment was carried out in drainage lysimeters under greenhouse conditions in Regolithic Neosol with sandy loam texture. Treatments consisted of two levels of electrical conductivity of water (ECw) (0.8 and 4.5 dS m-1) and four N doses (70; 85; 100 and 115% of the N recommendation), arranged in randomized blocks, with three replicates. The dose relative to 100% corresponded to 200 g of N per plant per year. Irrigation with 4.5 dS m-1 electrical conductivity water resulted in a reduction in stomatal conductance, transpiration, CO2 assimilation rate and instantaneous carboxylation efficiency but increased cell damage percentage and internal CO2 concentration in West Indian cherry plants. Inhibition of CO2 assimilation rate in West Indian cherry plants is related to non-stomatal effects. Irrigation with 4.5 dS m-1 water and fertilization with 115% of N recommendation intensified leaf water saturation deficit in the West Indian cherry crop. The BRS Jaburu West Indian cherry was sensitive to 4.5 dS m-1 water salinity.

Determinación de evapotranspiración y coeficiente de cultivo de <em>Myrciaria dubia</em> (Kunth) McVaugh para su domesticación y conservación en suelos de tierra firme

Myrciaria dubia (Kunth) McVaugh is a fruit tree native to the Amazon with great potential due to its nutraceutical properties; thus, ex situ adaptation technologies should be developed. The objective of this study was to determine the evapotranspiration (ETc) and crop coefficient (Kc) of Myrciaria dubia for domestication and conservation on uplands. Two Myrciaria dubia plants of 2, 4, and 6 years old with similar morphological characteristics of height, number of branches (basal and terminal), and diameter (stem and canopy) were transplanted into drainage lysimeters. Residue of organic mulching composed of a native grass (Trachypogon plumosus) was applied once to one plant of each age category. The mean ETc values for 2-, 4-, and 6-year-old plants in the presence and absence of mulch were 2- and 2.7-mm∙day-1, 3.2- and 3.9-mm∙day-1, and 6.1- and 7.2-mm∙day-1, respectively. The mean Kc values in the EI, EII, and EIII phenological stages with and without mulch were 0.4 and 0.6, 0.6 and 0.8, and 1.1 and 1.3, respectively. The ETc and Kc values for Myrciaria dubia plants with organic mulching can be used in irrigation planning for cultivation, domestication, conservation, and efficient use of water resources in tropical savannas of Roraima, Brazil.

Crop coefficient and water requirement of prickly pear in the Agreste region of Alagoas state, Brazil

ABSTRACT Prickly pear cultivation has played an important role in the Brazilian livestock farming, being used as forage for animals in the Northeast region, especially during the drying season, because it is an excellent source of water. Thus, the objective of this study was to estimate the crop coefficient and water requirement of prickly pear in the Agreste region of Alagoas state, Brazil. Prickly pear crop evapotranspiration (ETc) was determined using five drainage lysimeters, made of polyethylene with dimensions of 0.35 x 0.40 m (side and depth). Four soil layers were separated and put into the lysimeters in the opposite sequence, in order to maintain it as close as possible to the initial soil structure. The reference evapotranspiration (ETo) was estimated by the Penman-Monteith, Hargreaves-Samani and FAO-Radiation methods, using climatic data from the meteorological station of the Instituto Nacional de Meteorologia (INMET) in the city of Arapiraca, AL, Brazil. Crop coefficient (kc) was calculated by the ratio between ETc and ETo. The average kc obtained was 0.72, 0.84 and 0.48 for the Penman-Monteith, Hargreaves-Samani and FAO-Radiation methods, respectively. Keeping the soil under field capacity during the experimental period, the total crop evapotranspiration was 637.84 mm, with daily value equal to 4.22 mm d-1.

Gas exchanges and growth of passion fruit under saline water irrigation and H2O2 application

ABSTRACT The study was carried out to evaluate the photosynthetic efficiency and growth of yellow passion fruit, cultivated under different levels of irrigation water salinity and exogenous application of hydrogen peroxide. The experiment was carried out in greenhouse of the Universidade Federal de Campina Grande, PB, Brazil, using drainage lysimeters with capacity for 100 dm3, filled with Entisol of sandy texture. The experimental design was randomized blocks using a 4 x 4 factorial scheme, with three repetitions, corresponding to four water salinity (0.7; 1.4; 2.1 and 2.8 dS m-1) and four concentrations of hydrogen peroxide (0, 20, 40 and 60 µM). The different concentrations of hydrogen peroxide were applied by soaking the seed for a period of 24 h and spraying the leaves on the adaxial and abaxial sides. At 35 days after transplanting, the interaction between water salinity and hydrogen peroxide concentrations did not significantly interfere with plant physiology and growth, except for the number of leaves. The hydrogen peroxide did not cause significant effects on any of the evaluated plant variables. Increasing salinity of irrigation water led to reduction in gas exchanges at 61 and 96 days after transplanting. Water salinity inhibited the CO2 assimilation, transpiration, stomatal conductance, instantaneous carboxylation efficiency and stem diameter of passion fruit plants.

Investigation of the possibility of green bean production under unfavourable agro-ecological conditions in lysimeters

Abstract There are extended agricultural areas in the world that can be utilized only with irrigation for crop production. Improper irrigation may induce unfavourable processes in the soil (e.g. secondary salinization). To investigate this problem existing in Hungary as well, 12 simple drainage lysimeters – which are useful equipment for the investigation of the water and salt balance of the soil – were used in an irrigation experiment in the Research Institute of Karcag. The basic goal was to investigate the possibility of the production of a salt-sensitive crop (green bean) in areas with unfavourable agro-ecological conditions. 6 lysimeters were irrigated with deionized water, while the other 6 with saline water of 1,600 mg/l salt content. We also used a soil conditioner (Neosol) during the experiment. Analysing the effect of the irrigation quality on the plant height of green beans, it can be established that the plants irrigated with deionized water were averagely 5.3 cm taller than the plants irrigated with saline water. Similar tendencies were characteristic of the average biomass (deionized: 93.5, saline: 62.5 g), the average root mass (deionized: 9.5 g, saline: 8.2 g), the number of pods (deionized: 17.1, saline: 11.9), and the pod yield (deionized: 137.9 g, saline: 85.9 g) values. However, all these values can be improved by soil conditioning combined with the optimization of irrigation.

Feasibility of stabilised nitrogen fertilisers decreasing greenhouse gas emissions under optimal management in sprinkler irrigated conditions

Stabilised nitrogen (N) fertilisers with nitrification and urease inhibitors have been proposed to abate greenhouse gas (GHG) emissions in agrosystems. Nevertheless, differences in their application and in the management of water and nitrogen rates make it difficult to evaluate their actual utility. The aim of this study was to analyse the possibility for GHG emissions reduction in a 3-year rotation (maize-maize-wheat) by substituting the traditional split-urea application to maize by a single side-dress application of stabilised urea fertiliser. The experiment was performed in 24 drainage lysimeters in two contrasting soil types (Shallow and Deep) under efficient irrigation practices and adjusted N rates under Mediterranean conditions. Nitrous oxide (N2O) and methane (CH4) were measured using static closed unvented chambers, and the soil mineral N was monitored through periodic soil samplings. CH4 emissions were generally negligible with occasional tendency the soil acting as a sink more than as a net source. Direct N2O emissions during the whole rotation showed lower values when a nitrification inhibitor (3,4-dimethylpyrazole phosphate) was added than with conventional urea (Deep soil: 73% lower, p < 0.05; Shallow soil: 60% lower, ns). Urease inhibitors (N-(n-butyl) thiophosphoric triamide and monocarbamide dihydrogen sulphate) could not abate direct N2O emissions, and their effect depended on the soil type. However, all stabilised fertilisers mitigated N2O emissions in Deep soil when scaled by grain yield (average 54%). Indirect N2O emissions associated with nitrate leaching were not affected by the treatments but contributed more to total N2O emissions in Shallow soil (12%) than in Deep soil (6%). These results suggest that adequate use of nitrification inhibitors could have environmental benefits without lessening agronomic production.

Gas exchanges and production of West Indian cherry cultivated under saline water irrigation and nitrogen fertilization

West Indian cherry is of great socioeconomic importance to Brazil because of its potential to keep local workers in rural areas and generate income. It is mainly cultivated in the Northeast region, where high salt concentrations are common in water. This study was conducted to evaluate gas exchanges and production of West Indian cherry cultivar (cv.) ‘BRS 366 Jaburu’, as a function of irrigation with water of different salinity levels, and nitrogen fertilization, at the post-grafting stage. The experiment was carried out in pots adapted into drainage lysimeters, under greenhouse conditions in Campina Grande, PB, Brazil. The experimental design was randomized blocks with three replicates, using a 2 × 4 factorial arrangement in which the treatments corresponded to two levels of irrigation water electrical conductivity (ECw: 0.8 and 4.5 dS m-1) and four nitrogen doses (ND: 70, 85, 100, and 115% of the recommended dose). The 100% dose corresponded to 200 g of nitrogen per plant per year. Irrigation water electrical conductivity of 4.5 dS m-1 led to alterations in the gas exchanges and production components of West Indian cherry cv. ‘BRS 366 Jaburu’. An increase in intercellular CO2 concentration resulted in the occurrence of non-stomatal effects on the assimilation rate of CO2 under water salinity conditions of 4.5 dS m-1. The mean weight of West Indian cherry fruits was reduced when nitrogen doses were above 85% of the recommended level. Nitrogen doses above 70% of the recommended dose (140 g per plant) intensified the negative effects of salt stress on the total number and weight of West Indian cherry fruits.

Seasonal basal crop coefficient pattern of young non-bearing olive trees grown in drainage lysimeters in a temperate sub-humid climate

Young non-bearing olive trees were grown in drainage lysimeters and their water consumption was measured over two consecutive yearly-experimental periods to analyze the effect ofseasonal variations on the basal crop coefficient (Kcb). Micro-lysimeter measurements were used to quantify soil evaporation (Es) and Es was subtracted from evapotranspiration (ETc) to determine transpiration. Monthly mean (Kcb) were determined as (ETc-Es)/ETo, where ETo is the FAO-PM grass-reference evapotranspiration, calculated from locally measured weather data. The observed Kcb value at mid-season, 0.38, was obtained in the fall months, with 41% of canopy cover. The mid-season Kcb when adjusted to the FAO-56 standard climate was 0.43. Seasonal patterns of Kcb are presented and the Kcb value during the mid-season growth-stage was found to be similar to those described in the literature for Mediterranean climates. Variation of the basal crop coefficient was satisfactorily explained by measured canopy light interception (FIR) and a linear regression model is presented for Kcb as a function of FIR.

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.

Excessive nitrogen impairs hydraulics, limits photosynthesis, and alters the metabolic composition of almond trees

Horticulture nitrogen (N) runoffs are major environmental and health concerns, but current farming practices cannot detect ineffective N applications. Hence, we set to recognize high N conditions and characterize their effects on the physiology of almond trees grown in drainage lysimeters. Water and nutrients mass balances exhibited that N benefitted almond trees in a limited range (below 60 mg N L−1 in irrigation), while higher N conditions (over a 100 mg N L−1) reduced evapotranspiration (ET) by 50% and inherently constrained N uptake. Respectively, whole-tree hydraulic conductance reduced by 37%, and photosynthesis by 17%, which implied that high N concentrations could damage trees. Through gas-chromatography, we realized that high N conditions also affected components of the citric acid cycle (TCA) and carbohydrates availability. Such changes in the metabolic composition of roots and leaves probably interfered with N assimilation and respiration. It also determined the proportions between N and starch in almond leaves, which formed a new index (N:ST) that starts at 0.4 in N deficiency and reaches 0.6–0.8 in optimal N conditions. Importantly, this index continues to increase in higher N conditions (as starch reduces) and essentially indicates to excessive N applications when it exceeds 1.1.

Morphophysiology of Tahiti lime grafted onto Sunki mandarin hybrids under salt stress

ABSTRACT This study aimed to evaluate the growth and physiology of citrus scion/rootstock combinations irrigated with saline water until the pre-flowering stage. The experiment was conducted in drainage lysimeters with capacity for 150 dm3, in randomized block design in a 2 x 10 factorial scheme, corresponding to two electrical conductivities of water (S1 = 0.3 and S2 = 3.0 dS m-1) and ten scion/rootstock combinations (nine hybrids and one commercial variety) grafted with Tahiti lime, in three repetitions and one plant per plot. Grafted seedlings were transplanted one year after sowing, subjected to salt stress from 15 days after transplanting until the pre-flowering period, and evaluated for gas exchanges and growth. The irrigation with 3.0 dS m-1 saline water did not influence the photosynthetic activity of the studied citrus scion/rootstock combinations until the pre-flowering. The genotype Santa Cruz Rangpur lime (LCRSTC) was more sensitive to irrigation water salinity in terms of growth. The least sensitive combinations to salinity were Tahiti lime grafted onto TSKFL x (LCR x TR) - 018, TSKFL x TRBK - 011 and TSKFL x TRBK - 30.

Effect of Soil Conditioning on the Moisture Content and the Salt Profile of the Soil Under Irrigation with Saline Water

Abstract The research work was started on the preliminary knowledge that the risk of secondary salinization is high in the hobby gardens around Karcag as the water of the aquifers used for irrigation is saline, nevertheless irrigation in the drought periods is essential for vegetable production. A complex experiment was set up in 12 simple drainage lysimeters at the lysimeter station of the Research Institute of Karcag in 2012 in order to simulate the conditions of irrigation characteristic in the region with the goal of finding a solution to mitigate the harmful effects by means of optimization of irrigation. In 2017–2018 three approaches were applied for the scientific establishment of the problem studying the effect of different irrigation frequencies, different irrigation water qualities, and soil conditioning on the moisture content and the salt profile of the soil. The soil conditioner (Neosol) applied was found to have a positive effect on the water and salt regime of the soil, partly by creating a more favourable vertical distribution of the soil water, and partly preserving more moisture in the soil.

Water Use and Leaf Nutrient Status for Terraced Cherimoya Trees in a Subtropical Mediterranean Environment

Water scarcity in many semi-arid agricultural areas, in particular for the Mediterranean basin, is promoting changes in irrigated agriculture, with alternative strategies being introduced for water-use optimization. The coast of Granada and Malaga (Southeast Spain) is an economically important area for subtropical fruit cultivation. This intensively irrigated agriculture is characterized by requiring extra amounts of water and the adoption of sustainable practices to improve agricultural water management. A two-season experiment was conducted to assess (1) the water use in terraced cherimoya (Annona cherimola Mill. cv. Fino de Jete) orchards under conventional and organic production systems with drainage lysimeters, and (2) the impact on fruit yield and nutritional effects between the two considered production systems. Crop coefficient (Kc) values for cherimoya were 0.60–0.66, 0.64–0.71, and 0.48–0.62 at flowering, fruit set, and fruit growth, respectively. Fruit yield was similar in both systems, ranging from 47.1 for conventional to 44.1 kg tree−1 for organic farming, averaging 13.2 and 12.3 t·ha−1, respectively. No differences between these systems were observed in terms of leaf nutrient status, with variations in the N, P, and K contents during the different phenological stages. The N, P, and K lessen during flowering and fruit growth; the highest levels of these nutrients were fixed at harvest. These patterns were the opposite in Ca and Mg, ascribable to the antagonism between K and both Ca and Mg. Thus, these findings highlight the need to establish the optimal use of irrigation water with respect to crop requirements, thereby encouraging sustainable subtropical farming in terraces.

Growth and fluorescence of ‘Tahiti’ acid lime/rootstock on Sunki mandarin hybrids under salinity

The objective of this study was to evaluate the ecophysiological behavior of ‘Tahiti’ acid lime/rootstock grafted on Sunki mandarin hybrids during the prefloration stage of the plants, in the field, under saline stress. The progenies originating from crossings of the ‘Sunki’ mandarin with ‘Rangpur’ lime and Poncirus trioliata, as rootstocks, combined with the ‘Tahiti’ acid lime as a scion. The experiment was carried out under field conditions, at the Federal University of Campina Grande (UFCG), Pombal PB fields. In drainage lysimeter of 150 dm3, studying 10 scion/rootstock combinations, irrigated with two water salinity levels (CEa) (S1 = 0.3 and S2 = 3.0 dS m-1) making a 10 x 2 factorial scheme. The experimental design was a randomized block design, with 3 replicates and each plot consisting of a useful plant, totalizing 60 parcels. The scion/rootstock plants were transplanted at one year of age from the rootstocks sowing, being the beginning of the applications of the saline stress to the 15 days after the transplant lasting until the period of flowering, that is, up to 195 days after transplanting, During this period the plants were analyzed for growth and chlorophyll fluorescence a. The combinations less sensitive to salinity were composed of the ‘Tahiti’ grafted with TSKFL x (LCR x TR) - 018, TSKFL x TRBK - 011 and TSKFL x TRBK - 030, it being possible to use saline water with up to 3.0 dS m-1 in irrigation. Salinity did not damage the biochemical phase of the scion/rootstock combinations, only affecting the initial fluorescence of the lighted tissue.&#x0D;

Gas exchanges and growth of cotton cultivars under water salinity

ABSTRACT Indication of salt-tolerant cotton cultivars can make the agricultural exploitation with saline water irrigation feasible in the Brazilian semi-arid region. Thus, this study aimed to evaluate the gas exchanges and growth of cotton cultivars irrigated with saline water. The study was conducted in pots adapted as drainage lysimeters under greenhouse conditions, using a sandy loam Entisols as substrate. Treatments were distributed in completely randomized design, in 5 x 2 factorial arrangement, relative to five levels of irrigation water electrical conductivity - ECw (1.5, 3.0, 4.5, 6.0 and 7.5 dS m-1) and two cotton cultivars (BRS 368 RF and BRS Safira). Increase in irrigation water salinity inhibits the vegetative growth and gas exchanges of the cotton cultivars BRS Safira and BRS 368 RF. Leaf area and instantaneous carboxylation efficiency are the most affected variables. Physiological and growth performance of the cultivar BRS Safira in response to water salinity was higher than that of BRS 368 RF.