Partial Root-zone Irrigation Research Articles

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

Physiological and biochemical properties of wheat (Triticum aestivum L.) under different mulching and water management systems in the semi-arid region of Punjab, Pakistan

In order to meet the dietary requirements of the rising human population with diminishing water resources, there is the need to adopt techniques that optimize crop yield under reduced water conditions. Therefore, a greenhouse experiment was carried out to determine the effect of mulching and reduced irrigation on wheat production. The experiment included four mulching treatments (un-mulched, black plastic sheet mulch, wheat straw mulch and cotton sticks mulch) and two watering regimes (normal watering and partial root-zone drying irrigation (PRI) technique that involves alternate watering to only one side of root zone only) arranged in a completely randomized design. Wheat growth (leaf area index, plant height), water related parameters (leaf relative water contents (RWC), leaf turgor potential and physiological (chlorophyll contents, stomatal oscillation and photosynthetic rate) parameters and biochemical indicators were significantly higher with mulching than un-mulched for both irrigation levels. However, among the mulching treatments, the use of black plastic mulch gave the best results. Among the mulch treatments, RWC increased by 4.29%, 7.50% and 10.73% with black plastic mulch compared to wheat straw mulch, cotton stick mulch and control treatment, respectively. Between the two irrigation levels, higher wheat growth, physiological and water related parameters were found with full irrigation. Whereas leaf osmotic potential, quality traits and antioxidant enzymatic activities were higher with PRI. This study shows that, particularly with black plastic film, mulching combined with partial root zone drying can be effectively used in conserving soil water, thus increasing crop water use, photosynthetic rate, and yield.

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

Water Consumptive Use of Sorghum (Sorghum bicolor L.) under Partial Root Zone Irrigation in a Gypsifereous Soil

Water Consumptive Use of Sorghum (Sorghum bicolor L.) under Partial Root Zone Irrigation in a Gypsifereous Soil

Winter wheat root distribution with irrigation, planting methods, and nitrogen application

Soil water uptake is a function of root growth and distribution. Therefore, restrictions on root system growth may reduce water and nutrient uptake, which results in slower plant growth. The objective of this study was to determine the effects of different irrigation strategies, nitrogen application rates, and planting methods on the winter wheat root growth. The experimental factors included two irrigation strategies (variable alternate furrow irrigation defined as partial root-zone irrigation and ordinary furrow irrigation), two planting methods (in-furrow planting and on-ridge planting), and three nitrogen (N) application rates (0, 150, and 300 kg N ha−1) in 2015–2016 and 2016–2017 growing seasons. Results indicated that the in-furrow planting decreased mean root length density and root mass density (8% and 10%, respectively, in the fertilized treatments) compared to that obtained in the on-ridge planting. The partial root-zone irrigation reduced root length density by about 5% and 7% in the fertilized treatments compared to that obtained in full irrigation in the first and second year, respectively; however, these reductions were not statistically significant. Furthermore, the results implied that nitrogen fertilizer application increased root length density by 48% and 24% in the first and second year, respectively. Likely, root mass density increased by 32% and 5% in the first and second year, respectively. The exponential decaying relationship between root length density and soil depth indicated that the in-furrow planting with 300 kg N ha −1 produced the highest root density at the soil surface layer and reduced deep root penetration compared to the on-ridge planting and the other N treatments. Further analysis revealed that grain yield linearly correlated with root length density and root mass density in the first year. However, a polynomial (quadratic) relationship was obtained in the second year. Consequently, increasing the main root traits, including root length and root mass, enhanced winter wheat grain yield until it reached a threshold value. Higher values negatively affected grain yield, which might be due to allocating carbon to roots instead of grains.

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.

A review on Partial root-zone drying (PRD): A modern irrigation technique

Field experiments were conducted for 3 years from 2000 to 2002 to assess proportional crop yield differences obtained under conventional deficit irrigation (CDI) and partial root-zone irrigation (PRI) practices, compared with full irrigation (FULL) where plant water requirements were fully met. The experimental crops included vegetables (tomato and pepper), field crops (maize and cotton) and citrus. The fruit yield of greenhouse-grown tomato with FULL irrigation was higher than with PRI (7–22% lower) but was not significantly different. The PRD irrigation is a novel improvement of deficit irrigation in which half of the root zone is irrigated alternatively in scheduled irrigation events. In the last decade, scientists across the world, especially from arid to semi-arid countries, have extensively evaluated this irrigation as a water-saving irrigation strategy on agronomic and horticultural plants. This review paper focuses on the physiological and morphological aspects of PRD on plants and its ultimate impact on yield and water productivity. Overall, under limited water resources where water is precious, PRD is a viable irrigation option to increase water productivity while margining the yield, rather than only increasing the economic yield without concerning the value of water in limited water environments.

Yield and water productivity response of quinoa to various deficit irrigation regimes applied with surface and subsurface drip systems

AbstractThis study evaluated the yield and water productiivty response of quinoa to regulated deficit irrigation (RDI), partial root-zone drying (PRD) and conventional deficit irrigation (DI) and full irrigation (FI) using surface (SD) and subsurface drip (SSD) systems in 2016 and 2017 in the eastern Mediterranean region of Turkey. The treatments consisted of RDI, PRD50, DI50, DI75 and FI. A rainfed treatment (RF) was also included in the study. The experimental design was split plots with four replications. DI75 and DI50 received 75 and 50% of FI, respectively. PRD50 received 50% of FI, but from alternative laterals. RDI received 50% of FI during vegetative stage until flowering, and then received 100% of water requirement. The results showed that quinoa under SD used slightly more water than SSD due to reduced surface evaporation. RDI resulted in water saving of 23 and 21% for SD and SSD, respectively, compared to FI; and RDI produced statistically similar grain yields to FI. DI75 treatment resulted in water savings of 16% for both drip methods in the first year and 10 and 25% for SD and SSD systems, respectively, in the second year. PRD50 produced greater yield than DI50 eventhough they received the same amount of irrigation water. RF and PRD50 treatments resulted in significantly greater water productivity (WP) values than other treatments. There was no significant difference between SD and SSD regarding the grain and dry matter yields and WP values. Thus, RDI and DI75 appear to be good alternatives to FI for sustainable quinoa production in the Mediterranean region.

Preliminary Investigation on Crop Growth, Physiology, and Yield of Rice under Partial Root-Zone Irrigation

Rice is a staple food predominantly consumed by more than half of the global population. Water deficit is a crucial threat to produce rice globally. Prevailing water-saving techniques for rice can reduce water inputs but are not widely adopted due to the high yield penalty. Partial root-zone irrigation (PRI) is an innovative water-saving technique that allows simultaneous wet and dry areas within the root zone. We hypothesized that optimized PRI improves the water use and reduces the yield penalty of rice. A split root experiment was conducted on rice grown in pots with six defined PRI treatments, that is, PRI1, PRI2, PRI3, PRI4, PRI5, and PRI6. Half of the root system was wetted and alternated between halves with one- (PRI1), two- (PRI2), three- (PRI3), four- (PRI4), five- (PRI5), and six- (PRI6) day intervals. Conventionally irrigated rice plants where the whole root zone of rice was wetted and grown in the nonsplit pot were maintained and considered as control. Control and PRI treatments were irrigated based on 100% potential evapotranspiration demand (ETc). In particular, one PRI treatment (PRI3) showed a remarkable increase in active roots and leaf photosynthesis (PN) by wet and dry cycles within the root zone. Distinctive shoot responses of rice under PRI indicated enriched physiological responses for superior water productivity. The third-day-interval partial root-zone irrigation (PRI3) and conventional irrigation had similar leaf water potential (Ψleaf), while PRI3 had higher grain yield than conventional treatment and higher root surface area that may have compensated for the moderate level of stress in PRI. The finding that PRI scheduled at three-day intervals (PRI3) was superior to conventional irrigation for a single rice plant is promising and needs to be tested and adapted to field conditions.

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.

Response of grain yield and water use efficiency of wheat and faba bean to partial root-zone irrigation in intercropping

به منظور بررسی اثر روش‌های آبیاری و الگوهای کاشت بر عملکرد دانه و کارآیی مصرف آب گندم و باقلا آزمایشی مزرعه‌ای به صورت فاکتوریل در قالب طرح بلوک‌های کامل تصادفی در سه تکرار در سال 1396 در شهرستان شادگان اجرا شد. عامل اول شامل روش آبیاری (آبیاری کامل و جزئی سیستم ریشه‌ای) و عامل دوم شامل الگوهای مختلف کاشت (کشت خالص گندم و باقلا، کشت مخلوط ردیفی یک در میان و کشت مخلوط روی یک ردیف) بود. آبیاری محدود عملکرد دانه گندم را 24.4 درصد کاهش داد. با آبیاری جزئی ریشه، وزن دانه، ارتفاع بوته و عملکرد بیولوژیک گندم در کشت خالص 4، 9 و 9 درصد، در کشت مخلوط روی ردیف‌های جداگانه 6، 13 و 12 درصد و در کشت مخلوط روی‌ یک ‌ردیف 9، 18 و 18 درصد کاهش پیدا کرد. در آبیاری جزئی ریشه، وزن هزار دانه، تعداد دانه در بوته و عملکرد دانه باقلا به ترتیب 17، 45.8 و 35.9 درصد کاهش یافت. عملکرد باقلا در کشت‌های مخلوط‌ روی ردیف‌های جداگانه و روی یک ردیف به ترتیب 88 و 62 درصد کشت خالص بود که نشان می‌دهد باقلا از کشت مخلوط منتفع شده است. بهره-وری آب با اعمال آبیاری محدود (27 درصد) و کشت مخلوط (59 درصد) بهبود پیدا کرد. نسبت برابری زمین در کشت مخلوط روی یک ردیف و روی ردیف‌های جداگانه به ترتیب 1.68 و 1.55 بود که به معنی سودمندی کشت مخلوط نسبت به کشت خالص می‌باشد.

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.

The Productive, Economic, and Social Efficiency of Vineyards Using Combined Drought-Tolerant Rootstocks and Efficient Low Water Volume Deficit Irrigation Techniques under Mediterranean Semiarid Conditions

In many areas of southern Europe, the scarcity of water due to climate change will increase, making its availability for irrigation an even more limiting factor for agriculture. One of the main necessary measures of adaptation of the vineyards in these areas will be the implementation of water-saving irrigation strategies and technologies to improve WUE (water use efficiency). The objective of the present study was to evaluate the long-term economic viability/profitability of different deficit irrigation techniques such as regulated deficit irrigation (RDI) and partial root-zone irrigation (PRI) with low water volume/fertilizer applied in a Monastrell vineyard in southeastern Spain to plants grafted on different rootstocks, and to assess the productive, social, and economic efficiency in these semiarid conditions. Through a cost/benefit analysis, socio-economic and environmental criteria for the selection of optimal deficit irrigation strategies and tolerant/water use efficient rootstocks for the vineyards in arid environments are proposed. Our analysis shows a clear conflict between productivity and quality in wine grape production. Productive and economic indices, such as yield, productive WUE (kg m−3), economic efficiency (€ m−3), break-even point (kg ha−1), and water productivity (€ m−3), were inversely related with berry quality. Besides, high berry quality was closely related with higher production costs. Under the current market of low-priced grapes, if the grower is not rewarded for the quality of the grapes (considering technological, phenolic, and nutraceutical quality), the productivity vision will continue and the cost-effective option will be to produce a lot of grapes, even if at the expense of the berry and wine quality. In this situation, it will be difficult to implement optimized deficit irrigation strategies and sustainable irrigation water use, and the pressure on water resources will increase in semiarid areas. Public policies should encourage vine growers to invest in producing high-quality grapes as a differentiating character, as well as to develop agronomic practices that are environmentally and socially sustainable, by the grapes more adjusted to their real quality and production costs. Only in this way we can implement agronomic measures such as optimized low-input DI (deficit irrigation) techniques and the use of efficient rootstocks to improve WUE and grape quality in semiarid regions in a context of climate change and water-limiting conditions.

Physiological, biochemical and gene-expressional responses to water deficit in apple subjected to partial root-zone drying (PRD)

Water scarcity is one of the major factors limiting apple production. Partial root-zone drying (PRD) is a water-saving irrigation technique necessary to improve the efficiency of irrigation techniques to optimize the amount of fruit produced with the volume of water used. The apple trees cv. Red Delicious were exposed to four treatments, including (1) control with 100% of the crop evapotranspiration (ETc) needs; (2) alternate partial root-zone drying with 75% of the ETc needs (APRD75); (3) fixed partial root-zone drying with 75% of the ETc needs (FPRD75); (4) fixed partial root-zone irrigation with 50% of the ETc needs (FPRD50) in a semiarid region of Iran. Results showed that leaf water potential (Ψ leaf), and chlorophyll were significantly decreased in FPRD50 compared to control and other PRD treatments. APRD75 and FPRD75 treatments significantly enhanced (+) -catechin (+C), epicatechin (EC), chlorogenic acid (CGA), caffeic acid (CA) as well as increased water use efficiency (WUE) (by 30–40% compared to control) without significant reduction of yield. PRD reduced gibberellic acid (GA3) and kinetin, while, increased the abscisic acid (ABA) and salicylic acid (SA) levels. The abiotic stress-responsive transcription factors (TFs) MdoMYB121, MdoMYB155, MdbZIP2, and MdbZIP48 were highly expressed in all PRD treatments. Our results demonstrated that APRD75 and FPRD75 have the potential to stimulate antioxidant defense mechanisms, hormonal signaling pathways, and expression of drought-tolerance TFs to improve WUE while maintaining crop yield. Therefore, APRD75andFPRD75 with water savings as compared to full irrigation might be a suitable strategy 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.

Biomass accumulation and distribution, yield formation and water use efficiency responses of maize (Zea mays L.) to nitrogen supply methods under partial root-zone irrigation

Facing with the scarcity of water resource and irrational fertilizer use, it is highly important to supply plants with water and fertilizer in a coordination pattern to improve yield with high water use efficiency (WUE). A field experiment was conducted in 2012 and 2014 to investigate the effect of N supply methods on biomass accumulation and distribution, yield components and WUE of maize (Zea mays L.) under different partial root-zone irrigations in the Hexi corridor of Northwest China. Three irrigation methods included alternate furrow irrigation (AI), fixed furrow irrigation (FI) and conventional furrow irrigation (CI). Three N supply methods included alternate N supply (AN), fixed N supply (FN) and conventional N supply (CN), were applied in combination with each irrigation method. Leaf area index (LAI), shoot biomass and root length density at different growth stages, yield components, biomass distribution in different shoot organs and WUE of maize were determined. Results showed that, LAI at the R1, R2 and R4 stages, shoot biomass at the R6 stage, grain yield, harvest index (HI) and WUE of maize were significantly increased by AN or CN compared to FN in each irrigation method as well as by AI compared to CI and FI in each N supply method. Compared to CI coupled with CN (CICN), AI coupled with AN or CN (AIAN or AICN) significantly increased the LAI, shoot biomass, grain yield and WUE of maize. The biomass distribution proportion in kernel and contribution rate of the biomass transfer from other shoot organ to grain were also increased by AIAN and AICN, resulting in significantly higher HI. These increased shoot biomass accumulation and WUE were related to the enhanced LAI and root growth. AIAN and AICN also achieved a greater kernels number per cob and 1000-kernel weight compared to CICN. Thus, AI coupled with CN or AN are proposed as a better pattern of irrigation and nitrogen application with positive regulative effects on shoot biomass accumulation and distribution and WUE in the Hexi Corridor area of Northwest China and other regions with similar environments. These results can also provide a basis for in-depth understanding of the mechanism of biomass accumulation and growth responses to nitrogen supply methods.

Interactive effects of the rootstock and the deficit irrigation technique on wine composition, nutraceutical potential, aromatic profile, and sensory attributes under semiarid and water limiting conditions

Field-grown mature Monastrell grapevines grafted on five different rootstocks (140Ru, 1103 P, 41B, 110R, 161-49C) were subjected to regulated deficit irrigation (RDI) and partial root zone irrigation (PRI) in a semiarid region in SE Spain (D.O. Bullas, Region of Murcia). The main goal was to analyse the effects of the rootstock (R), irrigation method (IM), and their interaction (R x IM) on the final wine composition, volatile aromatic profile, and wine sensory attributes. The application of low annual water volumes (85–90 mm year−1) to low vigorous rootstocks (161-49C, 110R) was reflected in wines with higher contents of polyphenolics and alcohol, a higher wine quality index (QIwine), enhanced levels of health-promoting bioactive compounds (flavonols, malvidins), and better organoleptic perception compared to other rootstocks. These wines also had lower concentration of aromatic compounds (alcohols and esters). The 140Ru wines, although having a lower polyphenolic concentration and worse color, were among those rated most highly and preferred by the tasters. These wines had a high content of lactic acid and amino acids, higher tartaric/malic and anthocyanins/tannins ratios and a low concentration of aromatic compounds. In contrast, 1103 P and 41B wines had lower polyphenolic content-nutraceutical value, lower QIwine, tartaric/malic and anthocyanins/tannins ratios, more aromatic compounds, abundant green-vegetable/astringent notes, and more defect-causing compounds. In addition, these wines were also the worst rated in the sensory analysis. Significant positive correlations between the polyphenolic content and alcoholic degree and the score in the wine sensory analysis indicated that the greater the polyphenolic and alcohol contents in the wine, the better valued and more preferred by the tasters it was. PRI method improved wine quality and organoleptic perception for low vigor rootstocks (especially 161-49C), compared to RDI. These wines showed darker color, higher sugar content and nutraceutical potential as well as better sensory perception compared to other rootstock-IM combinations. In contrast, for high vigor rootstocks (1103 P, 140Ru), RDI was more beneficial for wine composition, global quality, and sensory perception. Overall, the PRI method also increased the presence of some volatile unpleasant alcohols in the wines. We recommend the use of low vigor rootstocks and DI techniques with small water volumes to improve Monastrell wine quality, and as a measure to adapt vineyards to climate change under semiarid and water limiting conditions.