Aiming at the problems of low photosynthetic performance and yield decline of maize leaves caused by large amount of plastic input and extreme high temperature in traditional maize planting in oasis irrigation area, the photosynthetic physiological mechanism of maize during grain filling period under two years of plastic mulching was studied, so as to provide the theoretical basis for the construction of high grain yield technology of plastic reduction in oasis irrigation area.

In 2013, a randomized block experiment was conducted in the oasis irrigation area of the Hexi Corridor. According to the duration of plastic mulching, three treatments were formed: no-tillage with plastic re-mulching and using (NTP), no-tillage in autumn and plastic mulching in spring (RTP), and conventional tillage with annual new plastic mulching (CTP, as the control). The response of chlorophyll content, gas exchange parameters, key enzyme activities of photosynthetic physiology, relative gene expression and key protein content of maize leaves to different plastic utilization methods was explored.

Different plastic utilization methods promoted the increase and stability of maize yield by regulating the photosynthetic physiological characteristics of maize filling stage. Compared with CTP, chlorophyll a and b in NTP filling stage increased by 15.1% and 8.3% on average, respectively, indicating that NTP treatment was beneficial to maintain the chlorophyll content of maize, thus effectively delaying the degradation of chlorophyll and promoting the photosynthesis of maize. Compared with CTP treatment, the net photosynthetic rate and transpiration rate under NTP increased by 25.2% and 11.5%, 20.0% and 12.2%, respectively, in the middle and late stages of grain filling, indicating that NTP treatment was beneficial to regulate the gas exchange parameters of maize during grain filling stage and enhanced the photosynthesis of maize during grain filling stage. At the same time, NTP maintained higher photosynthetic physiological key enzyme activity, relative gene expression and key protein content during the filling stage, which provided a guarantee for the improvement of photosynthesis. Compared with CTP, the activities of PPDK, PEPC, and Rubisco in maize leaves treated with NTP increased by 18.9%, 20.0%, and 30.6% on average, respectively, the gene expression of pepc, ppdk, and rub in maize leaves increased by 22.1%, 75.8%, and 70.6%, respectively, and the protein content of D1 and D2 in photosynthetic reaction center increased by 12.6% and 13.2%, respectively. Compared with CTP treatment, the activities of PPDK, PEPC and Rubisco in maize leaves under RTP increased by 15.6%, 16.4%, and 19.2%, respectively. The expression levels of pepc, ppdk, and rub genes in maize leaves increased by 13.6%, 53.9%, and 57.7%, respectively. The content of D1 protein in photosynthetic reaction center increased by 10.1%. In addition, the grain yield of NTP was 5.2%, 6.0%, and 5.3% higher than that under CTP in 2021, 2022, and 2023, respectively. The grain yield of RTP was only 5.2% higher than that under CTP in 2022.

No-tillage with plastic re-mulching and using was an effective cultivation and management measure to maintain high photosynthetic performance, reduce plastic input, and increase maize yield in the northwest oasis irrigation areas.

To address the scientific challenges of limited yield potential, inefficient resource use efficiency, and constrained economic benefits in equidistant maize planting in the Northwest oasis irrigation zones of China, this study investigated the effects of wide–narrow row planting patterns on maize density tolerance and yield potential.

This experiment began in 2017 and the data were collected from 2019 to 2021, using a split-plot design. The main plot treatments comprised three line spacing configurations characterized by alternating wide-narrow line spacing: L1 (7:3 ratio, 56 cm wide line spacing: 24 cm narrow line spacing), L2 (6:4 ratio, 48 cm wide line spacing: 32 cm narrow line spacing), and L3 (5:5 ratio: 40 cm wide line spacing, 40 cm narrow line spacing). The split-plot treatments were four maize planting densities: D1 (8.25×10⁴ plants/hm², local conventional planting density), D2 (9.00×10⁴ plants/hm², increased density by 9.1%), D3 (9.75×10⁴ plants/hm², increased density by 18.2%), and D4 (10.50×10⁴ plants/hm², increased density by 27.3%). The effects of these spacing arrangements under increasing planting density on maize photosynthetic characteristics, yield, resource utilization, soil nitrogen content, and economic benefits were investigated.

Both wide-narrow line spacing planting and increased maize planting density enhanced photosynthetic characteristics, yield, and resource utilization efficiency of maize in the Hexi Oasis Irrigation District. Compared with wide-narrow line spacing ratio of 5:5 treatment, wide-narrow line spacing ratio of 7:3 treatment increased maize average leaf area index, light interception score at the big flare stage, grain yield, light use efficiency, water use efficiency, and nitrogen use efficiency by 9.7%, 7.1%, 8.8%, 8.2%, 12.7%, and 14.1%, respectively. Increased density by 9.1% and 18.2% treatments increased maize average leaf area index by 11.4% and 15.7%, light interception score at the big flare stage by 7.4% and 10.1%, grain yield by 9.6% and 11.3%, light use efficiency by 4.0% and 6.1%, and water use efficiency by 10.2% and 20.5% than that with local traditional planting density, respectively. Wide-narrow line spacing ratio of 7:3 with an 18.2% density increase demonstrated significant potential for comprehensive improvement. Compared with wide-narrow line spacing ratio of 5:5 and traditional planting density, wide-narrow line spacing ratio of 7:3 and increased density by 18.2% increased average leaf area index by 28.4%, enhanced light interception score at big flare and grain filling stages by 22.0% and 17.1%, respectively, and raised grain yield, biomass, and harvest index by 22.2%, 13.1%, and 8.0%, respectively. Wide-narrow line spacing ratio of 7:3 and increased density by 18.2% also improved average leaf area index, water use efficiency, and nitrogen use efficiency by 13.5%, 39.6%, and 24.0%, respectively, while reducing soil total nitrogen, ammonium nitrogen, and nitrate nitrogen contents by 11.2%, 18.0%, and 16.8% compared with wide-narrow line spacing ratio of 5:5 and traditional planting density, respectively. Additionally, wide-narrow line spacing ratio of 7:3 and increased density by 18.2% treatment increased net profit and the ratio of benefit and cost by 50.1% and 23.3%, compared with wide-narrow line spacing ratio of 5:5 and traditional planting density, respectively.

The wide-narrow line spacing ratio cropping pattern of 7:3 enhanced the comprehensive effects of densely planted maize by improving photosynthetic characteristics, resource use efficiency, and soil nitrogen supply.

In terms of the issues of yield instability and quality deterioration caused by improper water and fertilizer application, the effects of reduced irrigation combined with organic and inorganic nitrogen fertilization on the yield and quality of silage maize in arid irrigated regions of Northwest China were investigated, so as to identify optimal water and fertilizer management practices for achieving high yield and superior quality in silage maize cultivation in the irrigated areas.

From 2021 to 2022, a field experiment based on two-factor split-plot design was carried out at the Oasis Agricultural Experimental Base of Gansu Agricultural University. The main factor was two irrigation levels, respectively, including I1 conventional irrigation reduction 20% irrigation was 324 mm, and I2 conventional irrigation is 405 mm, and drip irrigation was used. The sub-factor included five different fertilization regimes: F1, 100% chemical nitrogen fertilizer; F2, 75% chemical nitrogen fertilizer+25% organic fertilizer; F3, 50% chemical nitrogen fertilizer+50% organic fertilizer; F4, 25% chemical nitrogen fertilizer+75% organic fertilizer; and F5, 100% organic fertilizer. The effects of different water and fertilizer management practices on the yield, grain quality, and stalk quality of silage maize were analyzed, and the comprehensive evaluation of the yield and quality of silage maize was performed using factor analysis.

Reducing irrigation alone led to a decrease in the yield and quality of silage maize. However, the combined application of organic-inorganic nitrogen fertilizers helped to enhance the potential for simultaneously improving both yield and quality under reduced irrigation conditions. Notably, the combination of reduced 20% irrigation with 75% chemical nitrogen fertilizer+25% organic fertilizer (I1F2) demonstrated significant advantages. The I1F2 treatment significantly increased fresh and hay yields of silage maize, with fresh and dry grass yields improving by 9.9% and 12.7% over conventional irrigation combined with 100% chemical nitrogen fertilization (the control treatment, I2F1), respectively. Meantime, the I1F2 treatment was able to maintain a relatively high grain and stover quality of silage maize. Compared with I2F1, the I1F2 treatment increased protein and fat contents of grain by 17.4% and 20.5%, and increased essential amino acids content too, with phenylalanine, valine, leucine, isoleucine, tryptophan, threonine, lysine, and methionine rose by 17.4%, 13.9%, 19.4%, 17.9%, 23.1%, 30.0%, 44.5%, and 22.0%, respectively. The I1F2 treatment increased crude protein, crude fat, and soluble sugar contents in the stover by 13.9%, 19.1%, and 15.6% over I2F1, respectively, while decreasing neutral detergent fiber content by 13.5%, thereby improving relative feed value by 14.0%. Factor analysis also revealed that the I1F2 treatment had the highest composite applicability index, which was beneficial for increasing both the yield and quality of silage maize.

The combination of 20% reduced irrigation with 75% chemical nitrogen fertilizer+25% organic nitrogen fertilizer was the optimal water and nitrogen management practice for simultaneously enhancing both the yield and quality of silage maize in the Northwest irrigation areas.

The study investigated the regulatory effects of reduced irrigation and the combined application of organic and inorganic fertilizers on stay-green characteristics in leaves and yield performance of silage maize after tasseling stage, in order to explore the optimal nitrogen application ratio of organic and inorganic fertilizers under reduced irrigation conditions, so as to provide a theoretical basis for high-yield and efficient cultivation practices of silage maize in arid irrigation areas.

From 2021 to 2023, a two-factor split-plot experimental design was employed in the Hexi oasis irrigation area. The main plots consisted of two irrigation levels: reduced 20% irrigation (I1) and conventional irrigation (I2), while the subplots included five ratios of organic and inorganic fertilizer nitrogen fertilization maintaining equivalent nitrogen levels: 100% inorganic nitrogen fertilizer (F1), 75% inorganic nitrogen fertilizer+25% organic fertilizer (F2), 50% inorganic nitrogen fertilizer+50% organic fertilizer (F3), 25% inorganic nitrogen fertilizer+75% organic fertilizer (F4), and 100% organic fertilizer (F5). The study explored the response of stay-green characteristics in silage maize leaves after tasseling stage and fresh and hay yields to different irrigation amounts and organic-inorganic nitrogen fertilizer ratios.

The reduction in irrigation alone resulted in a decrease in leaf stay-green characteristics of silage maize after tasseling stage. However, combining reduced irrigation with the application of both organic and inorganic fertilizers enhanced leaf stay-green characteristics after tasseling stage. Among these combinations, the reduced 20% irrigation combined with 75% inorganic nitrogen fertilizer+25% organic fertilizer (I1F2) showed a significant advantage. I1F2 could increase leaf area index and stay-green in leaves of silage maize after tasseling. Compared with conventional irrigation combined with 100% inorganic nitrogen fertilizer (I2F1), I1F2 could increase leaf area index and stay-green in leaves by 14.3% and 6.8%, respectively. Compared with the I2F1 treatment, I1F2 also increased chlorophyll a and b content in leaves of silage maize by 14.2% and 10.7%, respectively. As the increase in chlorophyll a content was greater than that of chlorophyll b, a higher chlorophyll a/b ratio was achieved. 75% inorganic nitrogen fertilizer+25% organic fertilizer under conditions of 20% reduced irrigation enhanced the reactive oxygen species scavenging capacity in leaves of silage maize after tasseling stage. Superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase activities under I1F2 were increased by 12.0%, 7.8%, 10.7%, and 10.2% than that under I2F1, respectively. Compared with the I2F1 treatment, I1F2 increased proline and solute protein content in silage maize after tasseling stage by 9.8% and 9.7%, respectively, and reduced malondialdehyde content by 8.4%. Therefore, the silage maize under I1F2 could achieve higher fresh and hay yields at the optimal harvest time, increasing by 9.9% and 13.6% compared with I2F1. Comprehensive analysis indicated that I1F2 could significantly improve leaf area index, stay-green characteristics, and chlorophyll content of silage maize by enhancing leaf antioxidant enzyme activity, increasing content of cellular osmotic regulatory substances, and reducing malondialdehyde content after tasseling stage. Consequently, this effectively boosted the yield of silage maize.

Reduced 20% irrigation combined with 75% inorganic nitrogen fertilizer+25% organic fertilizer was an optimal water and nitrogen management strategy for extending the stay-green period of silage maize leaves after tasseling stage and increasing yield in arid irrigation areas.

Aiming at the problems of large amount of nitrogen fertilizer input, low utilization rate and single fertilizer source in traditional spring wheat planting in the oasis irrigation area of Northwest China, the effects of multiple cropping green manure after spring wheat on photosynthetic source, growth characteristics and yield of spring wheat under the condition of reduced nitrogen application were studied, with a view to provide the technical support for the construction of a nitrogen-saving and high-yield green planting model of spring wheat in the experimental area.

The split plot experiment was carried out in the oasis irrigation area of Hexi Corridor from 2021 to 2023. The main area was set up with two planting modes: post-wheat fallow (W) and post-wheat multiple cropping of hairy leaf (W-G), and the split plot was the traditional full nitrogen application of 100% (N1, 180 kg·hm^-2), reduced nitrogen application of 15% (N2, 153 kg·hm^-2) and reduced nitrogen application of 30% (N3, 126 kg·hm^-2). The photosynthetic source, stay-green of leaves, growth characteristics and yield performance related indicators of spring wheat under different treatments were measured and calculated. The Logistic equation of dry matter accumulation, the correlation between different indicators and the compensation index were constructed. The objective was to explore the compensation effect of multiple cropping green manure on the growth and yield of nitrogen-reduced spring wheat.

Post-wheat multiple cropping of green manure could compensate for the loss of photosynthetic source, growth characteristics and yield caused by nitrogen reduction to a certain extent. Among them, the compensation effect was the best under the condition of multiple cropping green manure after spring wheat combined with 15% nitrogen reduction (W-GN2), which showed super compensation and equal compensation effect. Multiple cropping of green manure significantly increased leaf area index, leaf area duration and stay-green of leaves in spring wheat at the late reproductive stage. Compared with the traditional post-wheat fallow total nitrogen fertilization (WN1), W-GN2 increased the average leaf area index, leaf area duration and stay-green of leaves by 17.7%, 17.5% and 7.6% on the 75-90 days after seedling, respectively. W-GN2 optimized the growth characteristics of spring wheat. Compared with WN1, the average dry matter accumulation, the maximum growth rate of dry matter and crop growth rate under W-GN2 increased by 6.2%, 6.9% and 5.1%, respectively, and the net assimilation rate decreased by 6.2%. Due to the compensation of multiple cropping green manure for photosynthetic source and growth characteristics, the photosynthesis, population growth and material accumulation rate of spring wheat remained high in the late growth stage, which was conducive to the improvement of grain yield. The grain yield under W-GN2 was 14.7% higher than that under WN1, which was mainly attributed to the compensation of the spike number, 1000-grain weight and harvest index by multiple cropping green manure, and W-GN2 was 6.5%, 6.9% and 13.2% higher than that under WN1, respectively. According to the correlation analysis, it was found that W-GN2 treatment had better performance in photosynthetic source, growth characteristics and grain yield formation, and mainly promoted the formation of yield by compensating the photosynthetic source of spring wheat.

Multiple cropping of hairy vetch after spring wheat with 15% reduction of nitrogen application could be used as a perfect production technology to regulate the photosynthetic source and growth characteristics of spring wheat in the northwest oasis irrigation area to achieve nitrogen saving and yield increase.

Water shortage and high fertilizer input have become the dominant factors restraining spring wheat production in arid oasis irrigated areas. It is urgent to study the technology of the effects of water and nitrogen reduction in different planting modes on dry matter accumulation and yield formation of spring wheat, so as to provide a theoretical and practical basis for efficient production of spring wheat with water and fertilizer saving.

A field experiment with split-split plot was conducted at arid oasis irrigated areas from 2020 to 2021. Two planting modes, including wide-width uniform sowing (W) and conventional strip sowing (C), were designed, with two irrigation levels on local conventional irrigation (I2, 2 400 m³·hm^-2) and local conventional irrigation reduced by 20% (I1, 1 920 m³·hm^-2), and three levels of nitrogen fertilizer at a local conventional nitrogen (N3, 225 kg·hm^-2), local conventional nitrogen reduced by 20% (N2, 180 kg·hm^-2), and local conventional nitrogen reduced by 40% (N1, 135 kg·hm^-2). The adaptability of spring wheat yield to water and nitrogen reduction under wide-width uniform sowing and conventional strip sowing was studied.

Compared wtih conventional strip sowing, the wide-width uniform sowing increased the maximum dry matter growth rate (V_max), average dry matter growth rate (V_mean), and dry matter accumulation rate after booting stage of spring wheat, and delayed the time of emergence of the highest dry matter growth rate (T_m). Compared with conventional strip sowing with conventional irrigation and nitrogen levels, the V_max and V_mean values of spring wheat under the wide-width uniform sowing were increased by 13.0%-23.4% and 11.0%-16.9%, respectively, and T_m was delayed by 3.3-3.7 days with the treatment on the reduction of 20% for water and nitrogen, so the growth and development dynamics of spring wheat could be effectively regulated by wide-width uniform sowing. The wide-width uniform sowing had greater grain and biomass yields by 11.0%-17.3% and 4.3%-9.6%, respectively, and the greater harvest index by 6.3%-6.9%, than conventional strip sowing. Furthermore, the grain and biomass yields were 16.0%-22.5% and 5.6%-13.2%, and harvest index was 8.2%-10.9% greater under wide-width uniform sowing with the reduction of 20% in water and nitrogen than those under the conventional strip sowing with conventional irrigation and nitrogen levels. There was no significant difference in grain and biomass yields, and harvest index of spring wheat was found between the reduction 20% of water and nitrogen, and the reduction of 20% irrigation and conventional nitrogen application under wide-width uniform sowing. The increase of spring wheat yield was mainly attributed to the synergistic of grains per ear and 1000-grain weight, which were increased by 3.9%-7.1% and 18.4%-22.7%, respectively, compared with conventional strip sowing with conventional irrigation and nitrogen application, and the 1000-grain weight increased by a greater extent. Path analysis showed that the reduction 20% of water and nitrogen in wide-width uniform sowing enhanced grain yield mainly through increasing harvest index and 1000-grain weight.

The wide-width uniform sowing could realize the simultaneous reduction 20% of water and nitrogen in spring wheat production, which was a feasible measure to save water and nitrogen for stable and high yield of spring wheat in oasis irrigation areas.

In the oasis irrigated agricultural region, the low resource utilization efficiency and the ratio of output/input are the most prominent constraints for crop production. In this study, the characteristics of light use efficiency, irrigation water productivity and economic benefit in different cropping patterns were investigated in the areas. Research on the sustainability of different cropping patterns would benefit crop production to save cost and increase income in this region.

A field experiment was carried out in a typical arid irrigation area, Wuwei, Gansu province, from 2018 to 2020, to determine the effects of different cropping patterns on leaf area duration, grain yields light utilization efficiency, irrigation water productivity and economic benefit of crops. The sustainability of different cropping patterns was evaluated based on the above indexes.

Multiple cropping of green manure after spring wheat harvested significantly increased the leaf area duration of the main-cultivate crops during the whole growth period. W-G//M increased leaf area duration of the main-cultivate crops by 7.7%-7.8%, compared with W//M. Compared with sole cropping and spring wheat-green manure multiple cropping, the intercropping increased the grain yield of main-cultivate crops and the inputs of production cost, simultaneously. There was no significant difference in the total grain yield between W-G//M and W//M in 2018 and 2019. However, W-G//M increased the total grain yield by 8.7% in comparison to W//M in 2020. Compared with M, W-G and W, W-G//M increased net return by 16.7%-26.5%, 78.5%-132.2% and 35.9%-78.8%, respectively. In two intercropping patterns, the net return of the W-G//M decreased by 7.2% in comparison to W//M treatment in 2018. However, the net return of two intercropping treatments showed not significantly different in 2019 and 2020, and the ratio of output/input showed a similar result. Multi-planting green manure after wheat harvested could significantly improve the light use efficiency of crops. W-G//M treatment increased light use efficiency by 7.2%-14.1% compared with W//M. The light use efficiency under W-G was increased by 23.5%-52.1% in comparison to W treatment. Compared with W, the productivity of irrigation water under W-G was significantly reduced by 48.6%-54.3% (irrigation water use efficiency) and 30.9%-39.8% (Economic benefit per cubic meter irrigation water), while there was no significant difference in the productivity of irrigation water under W-G//M and W//M. W-G//M had the highest sustainability index across three years.

Grain yield of main-cultivate crops and economic benefits were improved by intercropping and multiple cropping green manure after wheat harvested. The irrigation water productivity and light utilization efficiency were also increased, thereby improved the sustainability of this cropping pattern. Therefore, multiple cropping green manure after wheat harvested in wheat/maize intercropping could be used as a high-efficient utilization of resources and sustainable cropping pattern in arid irrigation areas.

The aim of this study was to explore the effects of returning green manure to soil on wheat yield under different nitrogen application levels in oasis irrigation areas, which had important guiding significance for establishing a green wheat production pattern based on the combined application of green manure and chemical nitrogen fertilizer.

From 2018 to 2020, a split plot experiment was conducted in the Hexi oasis irrigation areas of Gansu province. The main plot was set up with two planting patterns of sole wheat (W) and multiple cropping hairy vetch after wheat harvest (W-G), and the sub-plot had 5 nitrogen levels, including no nitrogen application (N₀), 55% N (N₁), 70% N (N₂), 85% N (N₃), 100% N (N₄), among which 100% N was the conventional nitrogen application rate of 180 kg·hm^-2. The leaf area index (LAI), leaf area duration (LAD), net assimilation rate (NAR) and grain yield at maturity stage and its constituent factors were measured during the whole growth period of wheat, in order to provide the basis for optimizing planting pattern and nitrogen application level in this area.

Compared with W, W-G significantly increased the mean LAI and LAD during the whole growth period of wheat by 9.5%-19.7% and 9.7%-21.0%, respectively; The moderate reduction of nitrogen fertilizer was beneficial to increase the mean LAI and LAD of wheat, with N₃ being the most prominent. Compared with W-N₃ and W-N₄, W-G-N₃ increased mean LAI by 4.1%-15.4% and 8.8%-17.5%, respectively, and the total LAD increased by 4.6%-9.2% and 16.8%-18.8%, respectively. W-G reduced the mean NAR of the whole growth period of wheat, which was 17.7% and 17.8% lower than that of sole wheat, respectively. Compared with W-N₃ and W-N₄, W-G-N₃ reduced mean NAR by 16.4%-17.5% and 26.5%-40.1%, respectively. Planting over-pressing hairy vetch after wheat harvest and moderately reducing nitrogen fertilizer increased the grain yield of wheat. Compared with W-N₃ and W-N₄, W-G-N₃increased the yield by 6.9%-16.7% and 7.9%-13.6%, respectively. Grey correlation analysis and correlation analysis showed that multiple planting hairy vetch after wheat harvest and appropriate nitrogen fertilizer yield high crop yields were mainly due to the synergistic increase of mean LAI, total LAD and yield components.

The treatment of multiple cropping hairy vetch after wheat harvest combined with 85% N fertilizer treatment promoted the growth of vegetative organs, which was conducive to the establishment, expansion and enrichment of the grain bank, thereby obtaining high yields. Therefore, W-G-N₃ was an ideal planting pattern and nitrogen application level for optimizing wheat yield performance indicators in oasis irrigation areas to obtain high yields.