Alternate Partial Root-zone Irrigation Research Articles

A 15N-Tracing Study to Explore the Coupling Effects of Biochar and Nitrogen Fertilizer on Tomato Growth, Yield, Nitrogen Uptake and Utilization, and the Rhizosphere Soil Environment under Root-Divide Alternative Irrigation

To investigate the coupling effects of biochar and nitrogen fertilizer on tomato growth, nitrogen uptake and utilization (NUU), and the soil environment, a pot experiment was conducted using 15N-tracing technology from March to July 2021 and from September 2021 to January 2022. Three biochar application rates (B0, B1, and B2; 0, 3, and 6 t/hm2, respectively) and three nitrogen levels (N1, N2, and N3; 150, 300, and 450 kg/hm2, respectively) were set up. The results show that the growth, yield, rate of 15N uptake, nitrogen derived from soil (Ndfs), total nitrogen (TN), 15N utilization, and recovery rate of tomatoes were improved under biochar application, but nitrogen derived from fertilizer (Ndff) gradually decreased. A Pearson correlation analysis showed that the 15N uptake, Ndfs, TN, rhizosphere soil organic matter, soil organic carbon, and TN were significantly positively correlated with the yield and lycopene content of tomatoes. The comprehensive benefit to the tomatoes was evaluated based on combination weighting with the help of the technique for order preference by similarity to ideal solution (TOPSIS). This indicates that the best planting mode was the B2N2 treatment, with a biochar rate of 6 t/hm2 and nitrogen levels of 300 kg/hm2, under the alternative partial root-zone irrigation.

The Effect of Adding Poly-γ-Glutamic Acid (γ-PGA) on the Moisture Content of Gypsiferous Soil Under Partial Drip Irrigation System

The alternate partial root-zone irrigation APRI is a modern irrigation method to save irrigation water. A field experiment was conducted to study the effect of the conventional irrigation(CI) system and the APRI system, using different levels of poly-γ-glutamic acid (γ-PGA) (0, 15, 30, 60, and 120) kg ha-1 in Gypsiferous Soil, on soil moisture content and water use efficiency. The APRI method achieved the best water extraction efficiency of 3.25 kg.m-3. The depths of water added in the traditional irrigation method were (435.58, 420.52, 416.71, 410.98, and 398.67) mm, and in the alternating irrigation method, they were (390.42, 370.50, 361.27, 340.40, and 322.40) mm for the additional levels of (γ-). PGA), respectively. The APRI method achieved an abundance of irrigation water compared with the CI of (11.57, 13.50, 15.35, 20.74, and 23.66)% for the different addition levels of (γ-PGA), respectively. The decrease in moisture content with the increase in the applied water voltage. There is a direct relationship between the amount of water available to the plant and the level of addition of (γ-PGA).

Effect of using reclaimed water via furrow and subsurface drip systems under alternate partial root-zone irrigation mechanism on crops growth and soil properties

AbstractThe growing population in the face of water scarcity inevitably necessitates the quest for alternative sources of irrigation water, which integrates them with irrigation strategies for improved agricultural productivity to meet the Sustainable Development Goals. A three-year field experiment was conducted in 2017, 2018, and 2019 to investigate the effect of water quality (reclaimed water (RW) and clean water (CW)), irrigation techniques (subsurface drip irrigation (SDI) and furrow irrigation (FUI)), irrigation methods (full irrigation (FI) and alternate partial root-zone irrigation (APRI) (70% ETc)), and their interactions on the fresh fruit yield (FY), irrigation water use efficiency (IWUE), and nitrogen use efficiency (NUE) of tomatoes. Further, electrical conductivity (EC), pH, and organic matter (OM) of soil were evaluated. The experiments were undertaken over three growing spring seasons in a greenhouse at the Chinese Academy of Agricultural Sciences in Henan Province, China. Throughout the three years of this study, the yield, the IWUE, and the NUE values of all treatments under RW were higher than those corresponding values under CW. The trend was the same under SDI as it was under FUI. Statistical analyses revealed that there was no significant effect (P > 0.05) of water quality, irrigation technique, and irrigation methods on the soil EC, pH, and OM over the three years. In addition, the interaction between the different experimental factors over the three years of the study was not significant. In conclusion, the application of RW under SDI can result in saving CW and increasing productivity without any negative effect on the investigated soil properties. Furthermore, when RW-SDI is used in conjunction with APRI, it can result in increasing IWUE.

Regulation of tomato yield and fruit quality by alternate partial root-zone irrigation strongly depends on truss positions

Regulation of tomato yield and fruit quality by alternate partial root-zone irrigation strongly depends on truss positions

Influence of Different Irrigation Water Qualities and Irrigation Techniques on the Soil Attributes and Bacterial Community Structure

Rising freshwater scarcities pose a serious threat to agricultural production. Reclaimed water (RW) is increasingly utilized as one of the alternative resources for irrigation in agriculture. Microbial communities play crucial roles in the soil microenvironment and can be used as effective indicators to assess the ecological influence of RW irrigation in soil. However, there is a lack of research on the effects of RW with different irrigation techniques on soil attributes and microbial communities. The present experiment was conducted in China to investigate the effect of two kinds of water qualities (RW and clean water (CW)), two kinds of irrigation methods (full irrigation (FI) and alternate partial root-zone irrigation (APRI)), and two kinds of irrigation techniques (furrow irrigation (FUI) and subsurface drip irrigation (SDI)) on soil chemical properties, heavy metal concentrations, and bacterial community structure. The APRI treatments received 70% of the irrigation water volume of FI. The results revealed that electrical conductivity (EC), nitrate nitrogen (NO3−-N), and heavy metal (Cu, Cd, Pb, Zn) concentrations in soil irrigated with RW were significantly higher in comparison to the soil irrigated with CW. SDI significantly decreased the contents of TN by 4.88%, the EC by 13.78%, and the heavy metal Cd concentration by 13.14% in soils than that irrigated with FUI treatment. APRI significantly decreased the heavy metal Cu concentration in soils by 6.26% compared to FI treatment. Proteobacteria, Chloroflexi, Acidobacteria, and Gemmatimonadetes in soil irrigated with RW were more abundant than that irrigated with CW. The irrigation water quality, soil moisture content, heavy metal content, TN, and EC under various irrigation techniques and methods significantly affected the structure of soil bacterial communities. In conclusion, we highlight that the SDI-APRI treatment can be an efficient irrigation practice for reducing the EC, heavy metal pollution, and the security risks of soil irrigated by RW.

Evaluation of Crop Water Status and Vegetation Dynamics For Alternate Partial Root-Zone Drip Irrigation of Alfalfa: Observation With an UAV Thermal Infrared Imagery

Characterization of the spatiotemporal patterns of crop water status and vegetation dynamics are a prerequisite to overcome water scarcity and obtain precise agricultural water management. Based on high-resolution aerial thermal imagery, we estimated crop water stress index (CWSI), transpiration rate (T), and crop growth status. The research was conducted with conventional subsurface drip irrigation (abbreviated as R) and alternate partial root-zone drip irrigation (abbreviated as P) under four different irrigation quotas: 0 mm, 10 mm, 20 mm, and 30 mm, which are denoted as CK, R10 (P10), R20 (P20), and R30 (P30), respectively. Results indicate that the CWSI is a suitable tool to define alfalfa water status under different irrigation regimes. The CWSI values reflect CK > R10 > R20 > P10 > P20 > R30 > P30, with values of 0.57, 0.41, 0.26, 0.24, 0.18, 0.17, and 0.13, respectively. The T values show that CK < R10 < P10 < R20 < P20 < R30 < P30, with values of 0.46 mm/h, 0.61 mm/h, 0.70 mm/h, 0.71 mm/h, 0.76 mm/h, 0.77 mm/h, and 0.78 mm/h, respectively. In addition, under the same irrigation quotas, the CWSI presented as P10, P20, and P30 was lower than R10, R20, and R30, respectively, while the T was the opposite. Taking the improved transpiration rate as the amount of water saving, it was demonstrated that the alternate partial root-zone drip irrigation was a water-saving method, and each increase of 10 mm in alternating irrigation quotas could save 67.2, 18.4, and 4.6% of water, respectively. This evaluation contributes to a better understanding of the spatiotemporal variations of water and growth status and provides references and theories for the development of modern precise agriculture.

Effects of Nitrogen Application Rates and Irrigation Regimes on Root Growth and Nitrogen-Use Efficiency of Maize under Alternate Partial Root-Zone Irrigation

Root growth and its adaptation are quite important for efficient use of water and nutrients. The present study investigated the effects of alternate partial root-zone irrigation (APRI) coupled with nitrogen application on root growth and nitrogen-use efficiency (NUE) of maize (Zea mays L.). Treatments (conducted at Wuwei City, northwest China) included APRI with controlled irrigation at 45%, 65%, and 80% of field capacity (FC) (W1, W2, and W3, respectively) coupled with nitrogen application rate of 100, 200, and 300 kg N ha−1 (N1, N2, and N3, respectively). The study found a significant interaction effect of irrigation regimes and nitrogen application rates on maize root growth and NUE. Compared with N2, N3 did not increase the length, surface area, weight, and volume of roots at the filling and maturity stages under W2, while it did under W3, which suggests that increasing nitrogen application rates did not compensate for the adverse effect of drought on root growth. In addition, NUE positively correlated with these root morphological parameters but negatively with the root-to-shoot ratio at the filling and maturity stages. The W2N2 treatment with moderate soil moisture and relatively high soil nitrate-nitrogen promoted total root growth and deeper roots and optimized vertical root distribution, with a low root-to-shoot ratio, resulting in the greatest NUE. These results suggest that moderately controlled irrigation (W2) combined with a reasonable nitrogen rate (N2) improves root growth and optimizes root distribution, resulting in a high NUE in maize under alternate partial root-zone irrigation.

Assessing the Effect of Irrigation with Reclaimed Water Using Different Irrigation Techniques on Tomatoes Quality Parameters

As the most important resource for life, water has been a central issue in the international agenda for several decades. Yet, the world’s clean freshwater supply is steadily decreasing due to climate change and extensive agricultural water demand for irrigated lands. Therefore, in addition to rational water use, we should use non-traditional water resources like Reclaimed Wastewater (RW). The present experiment was carried out in China over three years (2017, 2018, and 2019) to study the effects of two types of water qualities (reclaimed wastewater (RW) and clean water (CW)), two types of irrigation methods (Full irrigation (FI) and alternate partial root-zone irrigation (APRI)), and two types of irrigation techniques (Furrow irrigation (FUI) and subsurface drip irrigation (SDI)) on the main tomato fruit quality parameters. The APRI treatments obtained 70% of the FI irrigation water volume. The irrigation treatments of this study were: (1) SDI with APRI; (2) SDI with FI; (3) FUI with APRI; and (4) FUI with FI. These treatments were under RW and CW. Thus, the experiment consisted of eight treatments. The tomato fruit quality parameters studied were vitamin C (VC), total acidity (TA), protein content (PC), and total soluble sugar content (TSS). The results reveal that many measurements under reclaimed water (RW) had the highest values compared with clean water (CW), except in protein content (PC). The vast majority of values measured for PC under CW were slightly greater than the values under RW. Moreover, the results reveal that tomato quality in many measurements under APRI treatments increased compared with FUI. The statistical analysis generally shows that the fruit quality parameters were not significantly (p > 0.05) affected by the interaction between the irrigation treatments. In conclusion, the treatment SDI-APRI under RW can be an efficient irrigation method to reduce the consumption of clean water. Additionally, SDI-APRI offers a safe option because the physical contact between the wastewater, crops, and the farmers is minimized compare with the FUI treatment.

Double-root-grafting enhances irrigation water efficiency and reduces the adverse effects of saline water on tomato yields under alternate partial root-zone irrigation

Since most world regions face freshwater (FW) shortages, water-saving irrigation and irrigation with saline water (SW) are currently two inevitable agricultural practices for crop production. However, these two practices generally have adverse effects on crop yields. In this study, we investigated the effects of double-root-grafting (DRG) on plant growth, crop yields, tomato quality and root-zone properties under alternate partial root-zone irrigation (APRI) with FW or SW. Self-rooting (SR), DRG, conventional irrigation (CI), APRI, FW and SW were considered in the experimental design to create treatments that included (i) SR-CI-FW, (ii) SR-APRI-FW, (iii) DRG-APRI-FW, (iv) SR-APRI-SW and (v) DRG-APRI-SW. The DRG used here is a ‘tongue approach grafting’ method in which grafted plants retain both rootstock (eggplant) root and scion (tomato) root in order to maximize the effectiveness of grafting under abiotic stress. The tested salinity level was 3.51 mS cm−1 which had exceeded the threshold salinity of tomato (2.50 mS cm−1). In general, APRI application increased water productivity by 22.2–35.6%, but decreased fruit yields by 9.1–18.8% in SR plants (SR-APRI-FW vs. SR-CI-FW). However, under APRI conditions, DRG plants showed higher rate of plant growth and less salinity damage as compared to SR plants. Application of DRG significantly (P < 0.05) increased tomato fruit yields by 7.9–17.2% under standard conditions (DRG-APRI-FW vs. SR-APRI-FW) and by 14.2–27.4% under salinity conditions (DRG-APRI-SW vs. SR-APRI-SW). Taken together, double-root-grafting enhanced irrigation water efficiency and reduced the adverse effects of saline water on tomato yields under alternate partial root-zone irrigation.

Effects and evaluation of biogas slurry/water integrated irrigation technology on the growth, yield and quality of tomatoes

Reasonable techniques and methods in biogas slurry application are significant for the promotion of biogas slurry and the improvement of crop quality in agricultural production. To investigate the impacts of different biogas slurry application techniques on the water use efficiency, growth, yield, and quality of tomatoes, three irrigation techniques, and two application methods were considered in this study. The three irrigation techniques are alternate partial root-zone irrigation (APRI), fixed partial root-zone irrigation (FPRI), and two sides root-zone irrigation (TSRI). Two application methods refer to applying the biogas slurry with hole irrigation and surface irrigation. In addition, principal component analysis (PCA) and technique for order preference by similarity to ideal solution (TOPSIS) methods were adopted to evaluate the comprehensive quality and comprehensive indicators of tomatoes among different treatments. There are three hole irrigation treatments, T1 (APRI), T2 (TSRI), T3 (FPRI), and three surface irrigation treatments, T4 (APRI), T5 (TSRI), and T6 (FPRI) were set in two-season pot experiments. The results show that the plant height, dry matter accumulation, fruit yield, and water use efficiency present a similar descending trend for APRI, TSRI, and FPRI under the same methane irrigation method, yet show that the hole irrigation treatment was higher than the surface irrigation treatment for the same irrigation technique. These indicate that the coupling of APRI technique and hole irrigation is more conducive to the increase of plant production and water use efficiency. Meanwhile, T1 treatment can significantly improve the soluble sugar, sugar-acid ratio, VC content, soluble protein, soluble solid content, and firmness of tomato fruits, which are better for the taste, storage, and transportation of tomato fruit. The titratable acid content in tomato fruit is the highest in T2 treatment, followed by T5 treatment, indicating that TSRI technique may result in an accumulation of titratable acid and is not conducive to the taste of the tomato. The comprehensive nutritional quality and index evaluation results show that T1 treatment ranks the highest among all treatments, and can be used as an optimal irrigation method for the implementation of integrated water/biogas slurry. Keywords: biogas slurry, irrigation technique, coupling, quality evaluation, comprehensive index evaluation DOI: 10.25165/j.ijabe.20221505.6901 Citation: Zheng J, Qi X Y, Yang S H, Shi C, Feng Z J. Effects and evaluation of biogas slurry/water integrated irrigation technology on the growth, yield and quality of tomatoes. Int J Agric & Biol Eng, 2022; 15(5): 123–131.

Alternate Partial Root-Zone Drip Nitrogen Fertigation Reduces Residual Nitrate Loss While Improving the Water Use but Not Nitrogen Use Efficiency.

The efficient utilization of irrigation water and nitrogen is of great importance for sustainable agricultural production. Alternate partial root-zone drip irrigation (APRD) is an innovative water-saving drip irrigation technology. However, the coupling effects of water and nitrogen (N) supply under APRD on crop growth, water and N use efficiency, as well as the utilization and fate of residual nitrates accumulated in the soil profile are not clear. A simulated soil column experiment where 30–40 cm soil layer was 15NO3-labeled as residual nitrate was conducted to investigate the coupling effects of different water [sufficient irrigation (W1), two-thirds of the W1(W2)] and N [high level (N1), 50% of N1 (N2)] supplies under different irrigation modes [conventional irrigation (C), APRD (A)] on tomato growth, irrigation water (IWUE) and N use efficiencies (NUE), and the fate of residual N. The results showed that, compared with CW1N1, AW1N1 promoted root growth and nitrogen absorption, and increased tomato yield, while the N absorption and yield did not vary significantly in AW2N1. The N absorption in AW2N2 decreased by 16.1%, while the tomato yield decreased by only 8.8% compared with CW1N1. The highest IWUE appeared in AW2N1, whereas the highest NUE was observed in AW2N2, with no significant difference in NUE between AW2N1 and CW1N1 at the same N supply level. The 15N accumulation peak layer was almost the same as the originally labeled layer under APRD, whereas it moved 10–20 cm downwards under CW1N1. The amount of 15N accumulated in the 0-40 cm layer increased with the decreasing irrigation water and nitrogen supply, with an increase of 82.9–141.1% in APRD compared with that in CW1N1. The utilization of the 15N labeled soil profile by the tomato plants increased by 9–20.5%, whereas the loss rate of 15N from the plant-soil column system decreased by 21.3–50.1% in APRD compared with the CW1N1 treatment. Thus, APRD has great potential in saving irrigation water, facilitating water use while reducing the loss of residual nitrate accumulated in the soil profile, but has no significant effect on the NUE absorbed.

Effect of partial root zone irrigation on growth and yield of sorghum (Sorghum bicolor L.) in a gypsifereous Soil

A field experiment was carried out to study the effect of partial root zone irrigation on growth and yield of sorghum (Sorghum bicolor L.) in a gypsifereous Soil , at the experimental station of the college of Agriculture, Tikrit university, located at 34°40 49 and 43° 38 40 longitude and 129m above sea level . The experiment was conducted with a randomized complete block design (RCBD). The Irrigation treatments Included Conventional Irrigation, Fixed Partial Root-Zone Irrigation and Alternate Partial Root-Zone Irrigation (I1 , I2 , I3). were applied during one of the four growth stages, which are the emergence phase, the vegetative phase, the flowering stage and seeds development (S1 , S2 , S3 , S4 .( Sorghum seeds (var. Inkath) were sown during autumn season on 7/21/2019 and harvested on 11/20/2019 . The results showed that the Alternate Partial Root-Zone Irrigation treatment were better than other irrigation treatments in all field indicators, The vegetative stage gave the lowest results . I3 S4 treatment were 5567.69 Cm2 plant-1 ,7057.05, 4781,53 and 5241.92 kg.ha-1 for leaves area , shoots and root dry mater , grain yield respectively

Effect of Nitrogen Supply Methods on the Gas Exchange, Antioxidant Enzymatic Activities, and Osmoregulation of Maize (Zea mays L.) Under Alternate Partial Root-Zone Irrigation

Effect of Nitrogen Supply Methods on the Gas Exchange, Antioxidant Enzymatic Activities, and Osmoregulation of Maize (Zea mays L.) Under Alternate Partial Root-Zone Irrigation

Effects of Soil Water Deficit at Different Growth Stages on Maize Growth, Yield, and Water Use Efficiency under Alternate Partial Root-Zone Irrigation

To investigate the effects of alternate partial root-zone irrigation (APRI) and water deficit at different growth stages on maize growth, physiological characteristics, the grain yield, and the water use efficiency (WUE), a pot experiment was conducted under a mobile automatic rain shelter. There were two irrigation methods, i.e., conventional irrigation (CI) and APRI; two irrigation levels, i.e., mild deficit irrigation (W1, 55%~70% FC, where FC is the field capacity) and serious deficit irrigation (W2, 40%~55% FC); and two deficit stages, i.e., the seedling (S) and milking stage (M). Sufficient irrigation (W0: 70%~85% FC) was applied throughout the growing season of maize as the control treatment (CK). The results indicated that APRI and CI decreased the total water consumption (ET) by 34.7% and 23.8% compared to CK, respectively. In comparison to CK, APRI and CI increased the yield-based water use efficiency (WUEY) by 41% and 7.7%, respectively. APRI increased the irrigation water efficiency (IWUE) and biomass-based water use efficiency (WUEB) by 8.8% and 25.5% compared to CK, respectively. Additionally, ASW1 had a similar grain yield to CK and the largest harvest index (HI). However, the chlorophyll and carotenoid contents were significantly reduced by 13.7% and 23.1% under CI, and by 11.3% and 20.3% under APRI, compared to CK, respectively. Deficit irrigation at the milking stage produced a longer tip length, resulting in a lower grain yield. Based on the entropy weight method and the technique for order preference by similarity to an ideal solution (TOPSIS) method, multi-objective optimization was obtained when mild deficit irrigation (55%~70% FC) occurred at the seedling stage under APRI.

Effects of nitrogen application rates and irrigation regimes on grain yield and water use efficiency of maize under alternate partial root-zone irrigation

Faced with the scarcity of water resources and irrational fertilizer use, it is critical to supply plants with water and fertilizer in a coordinated pattern to improve yield with high water use efficiency (WUE). One such method, alternate partial root-zone irrigation (APRI), has been practiced worldwide, but there is limited information on the performance of different irrigation regimes and nitrogen (N) rates under APRI. The objectives of this study were to investigate the effects of varying irrigation regimes and N rates on shoot growth, grain yield and WUE of maize (Zea mays L.) grown under APRI in the Hexi Corridor area of Northwest China in 2014 and 2015. The three N rates were 100, 200 and 300 kg N ha−1, designated N1, N2 and N3, respectively. The three irrigation regimes of 45–50%, 60–65% and 75–80% field capacity (FC) throughout the maize growing season, designated W1, W2 and W3, respectively, were applied in combination with each N rate. The results showed that W2 and W3 significantly increased the plant height, stem diameter, crop growth rate, chlorophyll SPAD value, net photosynthetic rate (Pn), biomass, grain yield, ears per ha, kernels per cob, 1 000-kernel weight, harvest index, evapotranspiration and leaf area index (LAI) compared to W1 at each N rate. The N2 and N3 treatments increased those parameters compared to N1 in each irrigation treatment. Increasing the N rate from the N2 to N3 resulted in increased biomass and grain yield under W3 while it had no impact on those under the W1 and W2 treatments. The W3N3 and W2N2 and W2N3 treatments achieved the greatest and the second-greatest biomass and grain yield, respectively. Increasing the N rate significantly enhanced the maximum LAI (LAI at the silking stage) and Pn under W3, suggesting that the interaction of irrigation and fertilizer N management can effectively improve leaf growth and development, and consequently provide high biomass and grain yield of maize. The W2N2, W2N3 and W3N3 treatments attained the greatest WUE among all the treatments. Thus, either 60–65% FC coupled with 200–300 kg N ha−1 or 75–80% FC coupled with 300 kg N ha−1 is proposed as a better pattern of irrigation and nitrogen application with positive regulative effects on grain yield and WUE of maize under APRI in the Hexi Corridor area of Northwest China and other regions with similar environments. These results can provide a basis for in-depth understanding of the mechanisms of grain yield and WUE to supply levels of water and nitrogen.

Biochar and alternate partial root-zone irrigation greatly enhance the effectiveness of mulberry in remediating lead-contaminated soils

Abstract Aims Soil lead contamination has become increasingly serious and phytoremediation can provide an effective way to reclaim the contaminated soils. This study aims to examine the growth, lead resistance and lead accumulation of mulberry (Morus alba L.) seedlings at four levels of soil lead contamination with or without biochar addition under normal or alternative partial root-zone irrigation (APRI). Methods We conducted a three-factor greenhouse experiment with biochar (with vs. without biochar addition), irrigation method (APRI vs. normal irrigation) and four levels of soil lead (0, 50, 200 and 800 mg·kg−1). The performance of the seedlings under different treatments was evaluated by measuring growth traits, osmotic substances, antioxidant enzymes and lead accumulation and translocation. Important Findings The results reveal that mulberry had a strong ability to acclimate to soil lead contamination, and that biochar and APRI synergistically increased the biomass and surface area of absorption root across all levels of soil lead. The seedlings were able to resist the severe soil lead contamination (800 mg·kg−1 Pb) by adjusting glutathione metabolism, and enhancing the osmotic and oxidative regulating capacity via increasing proline content and the peroxidase activity. Lead ions in the seedlings were primarily concentrated in roots and exhibited a dose–effect associated with the lead concentration in the soil. Pb, biochar and ARPI interactively affected Pb concentrations in leaves and roots, translocation factor and bioconcentration. Our results suggest that planting mulberry trees in combination with biochar addition and APRI can be used to effectively remediate lead-contaminated soils.

Effect of partial root zone irrigation on physiology, water use efficiency, fruit yield, phenolic compounds and antioxidant capacity of apple

ABSTRACT Apple is an important fruit tree in semi-arid and arid regions, but increasing water scarcity limits apple production. Earlier studies have reported that partial root-zone irrigation (PRI) can increase water use efficiency (WUE), but the effects of PRI on fruit quality and nutritional value are still less known. To close this knowledge gap, a two-year field experiment conducted to evaluate the effect of PRI treatments on biochemical properties, WUE, and stomatal leaf traits in the Red Delicious and Braeburn apple cultivars. The results showed that alternate partial root-zone irrigation (APRI75) and fixed partial root-zone irrigation (FPRI75) increased WUE by about 20–36% compared to control, respectively, but there was no significant difference in WUE between control and FPRI50. The highest antioxidant capacity, phenolic compounds, and phenylalanine ammonia-lyase (PAL) activity recorded in PRI treatments compared to control. In addition to improving the WUE and maintaining the yield, using APRI75 and FPRI75 to irrigate apple trees could be more effective in improving antioxidant capacity and phytochemical compounds such as anthocyanins and leading to increased nutritive value and quality of the apple fruits. Therefore, APRD75 and FPRD75 as potential water savings strategies might be suitable for irrigation apple trees under water scarcity.

Effects of nitrogen supply methods on fate of nitrogen in maize under alternate partial root-zone irrigation

Partial root-zone irrigation (PRI) has been practiced worldwide, but little information is available on nitrogen (N) supply methods influence on fate of applied N fertilizer for crop production under PRI. A field experiment was conducted to investigate effect of N supply methods on the uptake, residual, and loss of applied N fertilizer in maize (Zea mays L.) under alternate PRI at Wuwei, northwest China in 2014. 15N-labeled urea was used as N fertilizer. Two irrigation methods included alternate furrow irrigation (AI) and conventional furrow irrigation (CI). Two N fertilizer supply methods included conventional N supply (CN) and alternate N supply (AN), were applied in combination with each irrigation method. Grain yield, root length density (RLD), N uptake by maize at the maturity stage, and atom % of 15N excess, residual 15N and residual NO3-N in the 0-100 cm soil layer after maize harvest were determined. Results shown that compared to CI coupled with CN, AI coupled with AN or CN significantly increased the grain yield, harvest index, RLD, N uptake by maize, 15N accumulation in grain, atom % of 15N excess in the 0-60 cm soil layer, the residual 15N and 15N uptake rates; but significantly decreased the residual NO3-N in the 0-100 cm soil layers and 15N loss rate. Moreover, the synchronized rather than separation supply of N fertilizer and water enhanced the most above parameters under AI. 15N uptake rate was positively correlated with RLD in the 0-40 cm soil layer, suggesting that the enhanced RLD contributed to the improved 15N uptake rate. Therefore, alternate furrow irrigation coupled with conventional or alternate nitrogen supply (synchronized supply of N fertilizer and water) could help improve 15N uptake rate and reduce the 15N loss rate. Keywords: 15N-labeled technology, root length density, nitrogen fertilizer fate, nitrogen management, residual nitrogen DOI: 10.25165/j.ijabe.20201303.5287 Citation: Qi D L, Hu T T, Song X. Effects of nitrogen supply methods on fate of nitrogen in maize under alternate partial root-zone irrigation. Int J Agric & Biol Eng, 2020; 13(3): 129–135.

Effects of nitrogen supply methods on fate of nitrogen in maize under alternate partial root-zone irrigation

Partial root-zone irrigation (PRI) has been practiced worldwide, but little information is available on nitrogen (N) supply methods influence on fate of applied N fertilizer for crop production under PRI. A field experiment was conducted to investigate effect of N supply methods on the uptake, residual, and loss of applied N fertilizer in maize (Zea mays L.) under alternate PRI at Wuwei, northwest China in 2014. 15N-labeled urea was used as N fertilizer. Two irrigation methods included alternate furrow irrigation (AI) and conventional furrow irrigation (CI). Two N fertilizer supply methods included conventional N supply (CN) and alternate N supply (AN), were applied in combination with each irrigation method. Grain yield, root length density (RLD), N uptake by maize at the maturity stage, and atom % of 15N excess, residual 15N and residual NO3-N in the 0-100 cm soil layer after maize harvest were determined. Results shown that compared to CI coupled with CN, AI coupled with AN or CN significantly increased the grain yield, harvest index, RLD, N uptake by maize, 15N accumulation in grain, atom % of 15N excess in the 0-60 cm soil layer, the residual 15N and 15N uptake rates; but significantly decreased the residual NO3-N in the 0-100 cm soil layers and 15N loss rate. Moreover, the synchronized rather than separation supply of N fertilizer and water enhanced the most above parameters under AI. 15N uptake rate was positively correlated with RLD in the 0-40 cm soil layer, suggesting that the enhanced RLD contributed to the improved 15N uptake rate. Therefore, alternate furrow irrigation coupled with conventional or alternate nitrogen supply (synchronized supply of N fertilizer and water) could help improve 15N uptake rate and reduce the 15N loss rate. Keywords: 15N-labeled technology, root length density, nitrogen fertilizer fate, nitrogen management, residual nitrogen DOI: 10.25165/j.ijabe.20201303.5287 Citation: Qi D L, Hu T T, Song X. Effects of nitrogen supply methods on fate of nitrogen in maize under alternate partial root-zone irrigation. Int J Agric & Biol Eng, 2020; 13(3): 129–135.

Effects of partial root‐zone irrigation and nitrogen forms on the movement of nitrate in deep subsoil and its utilization by tomato plants

AbstractThe fate of residual nitrogen (N) in specific soil layers under partial root‐zone irrigation (PRI) and fertilized with different N forms was studied using a soil column experiment with 15N‐labelled N (K15NO3) applied to 110‐cm‐deep soil layers. We found that alternate PRI (APRI) saved 34.3% more irrigation water but only decreased yield by an average of 6.2%, whereas fixed PRI (FPRI) and deficit irrigation (DI) reduced fruit yield by an average of 25.5 and 35.0%, respectively, compared to conventional sufficient irrigation (CI). Using the same irrigation mode, nitrate‐N application significantly promoted 15N‐utilization by the tomato fruit and crops for all irrigation modes. Compared to ammonium‐N application, nitrate‐N application increased the recovery rate of 15N‐labelled N in plants by 30.6% under CI, 14.3% under APRI, 22.8% under FPRI, and 10.6% under DI. The 15N accumulation peak was found at a depth of 40–60 cm, corresponding to an upward 15N migration distance of 65 cm for all treatments. However, a significant difference in the amount of residual N in the crop root zone (0–100 cm) was observed between CI and the other irrigation methods.Highlights Effects of PRI on the fate of residual nitrate studied with the15N tracer technique and simulated soil column. APRI could save 34.3% irrigation water without significant effects on tomato yield. Nitrate‐N application significantly promoted the growth of tomato. The residual nitrate in deep subsoil mainly moved upward under all irrigation modes.