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.

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.

Aiming at the problems of large nitrogen input, single fertilizer source, low nitrogen utilization rate, and poor quality of wheat in spring wheat cultivation in Hexi areas of Gansu Province, the objective of this study is to explore the effects of suitable green manure and reduced nitrogen fertilizer cultivation techniques on grain yield and quality, and nitrogen absorption and utilization of spring wheat, and to provide a theoretical basis for high yield, high quality, and green production of wheat in Hexi irrigation areas.

A split plot experiment was conducted from 2019 to 2021 in the Hexi oasis irrigation areas of Gansu Province. Two cropping patterns of multiple green manure after wheat (W-G) and sole wheat (W) were set in the main plot. There were five N fertilizer levels in the sub-plot: 100% of conventional N fertilizer by the farmer (180 kg·hm^-2, N₄), 85% of conventional N fertilizer (N₃), 70% of conventional N fertilizer (N₂), 55% of conventional N fertilizer (N₁), and no N fertilizer (N₀).

Multiple green manure after wheat combined with 85% N application (W-G-N₃) was effectively increased wheat grain yield and biomass. The grain yield of W-G-N₃ was increased by 16.7%-18.4% and 13.6%-34.4%, respectively, compared with the 85% N application (W-N₃) and conventional N application (W-N₄) treatments for the sole wheat. The biomass of W-G-N₃ was increased by 11.3% (2020) and 5.2%-11.6% (2020 to 2021), respectively, compared with the W-N₃ and W-N₄ treatments. The increase of grain yield was greater than that of biomass, thus, the W-G-N₃ treatment had higher harvest index, which was 4.9%-15.9% and 8.0%-20.5% higher than that of W-N₃ and W-N₄ treatments. Meanwhile, the W-G-N₃ treatment improved grain quality of wheat by increasing protein content, sedimentation value, and wet gluten content, among which, the protein content, sedimentation value, and wet gluten content of W-G-N₃ were increased by 12.3%-16.1%, 28.7%-47.2%, and 10.7%-11.1%, respectively, compared with W-N₃; The protein content of W-G-N₃ was increased by 8.9%-12.4% compared with W-N₄, but the differences in sedimentation value and wet gluten content between W-G-N₃ and W-N₄ were not significant. In addition, the W-G-N₃ treatment was beneficial to promote nitrogen uptake and conversion to grain yield in wheat compared with W-N₃ and W-N₄ treatments, in which the N uptake was increased by 42.2%-58.9% and 35.2%-45.0%, N use efficiency was increased by 12.0%-20.6% and 5.9%-20.4%, respectively, and N partial factor productivity was increased by 3.6%-18.3% and 28.1%-58.1%, respectively. The W-G-N₃ treatment could compensate for the reduction of N agronomic efficiency, which was 74.2%-80.0% higher than W-G-N₄ treatment. The correlation analysis showed that multiple green manure after wheat combined with moderate reduction of N fertilizer increased grain yield by promoting efficient nitrogen uptake and utilization, and also significantly improved grain nutritional quality.

The combination of multiple green manure after wheat with 85% (153 kg·hm^-2) nitrogen application is the suitable cropping pattern and nitrogen application level to boost wheat yield, improve wheat grain quality, and increase nitrogen use efficiency in Hexi oasis irrigated areas.

In view of the problems of excessive application of nitrogen fertilizer and lower water resource utilization efficiency and economic benefits in crop production in the irrigation area of Hexi Oasis, the aim of this study was to explore the effects of multiple green manures after wheat and moderate reduction of chemical nitrogen fertilizer on the water consumption characteristics and economic benefit of wheat field.

From 2019 to 2020, a split plot experiment was conducted in the oasis irrigation area of Hexi, Gansu province. Two planting patterns were set up in the main area, namely, multiple cropping of green manure after wheat harvest (W-G) and single cropping of wheat (W). In the sub-plot, there were five nitrogen application levels, namely no nitrogen application (N₀), conventional nitrogen application level 180 kg·hm^-2 (N₄), reduced 45% nitrogen application (N₁), reduced 30% nitrogen application (N₂), and reduced 15% nitrogen application (N₃).

Grain yield of wheat and systematic biothermal energy were significantly increased by multiple green manure after wheat (W-G) and the moderate reduction of chemical nitrogen fertilizer, in 2019 and 2020, which increased by 10.8% and 12.4%, respectively, and the yield of systematic biothermal energy increased by 37.8% and 40.3%, respectively. Compared with nitrogen reduction of 15% (W-G-N₃) in sole wheat and traditional nitrogen application (W-N₄) in sole wheat, the grain yield increased by 6.9%-16.7% and 7.9%-13.6%, respectively, and the biothermal energy yield increased by 52.0%-62.2% and 27.1%-58.9%, respectively. The water consumption of W-G decreased by 6.3%-16.0% compared with that of W wheat growing stage, and W-G-N₃ decreased the seasonal water consumption of W-N₃ and W-N₄ by 13.4%-20.5% and 20.8%-29.0%, respectively. Repeated planting of green manure could improve the water use efficiency of wheat, and W-G increased by 7.9% and 19.2%, respectively. In 2019, compared with W-N₃ and W-N₄, the WUE of W-G-N₃ increased by 23.5% and 5.1%, respectively. Compared with W-N₃ and W-N₄, W-G-N₃ could improve the energy yield of per unit water efficiency of the system, which was increased by 2.7%-14.5% and 9.3%-17.5%, respectively. Compared with the W and W-G increased the cost input, and the gross output also increased. In 2019, the net return of W-G-N₃ increased by 9.8% and 9.5% compared with W-N₃ and W-N₄, respectively; in 2020, the net return of W-G-N₃ decreased by 15.6% and 15.7% compared with W-N₃ and W-N₄, respectively. In 2019 and 2020, the output/input of multiple cropping green manure after wheat harvest reduced by 20.7% and 23.1% compared with sole wheat, and the output/input of W-G-N₃ was 14.8%-23.1% compared with W-N₃ and W-N₄, and W-G reduced the benefit per cubic meter water of the system due to more resources input.

In the Hexi oasis irrigation areas, multiple green manure after wheat combined with moderate reduction of chemical nitrogen fertilizer could improve crop yield and economic benefit, as well as water resource utilization efficiency, among which the comprehensive effect of multiple green manure after wheat combined with 15% nitrogen treatment is outstanding, which could be used as an ideal planting pattern and nitrogen application level to improve water resource utilization and farmers' income.

The aim of this study was to explore the effects of multiple-cropping green manure and reduced nitrogen (N) application on water use characteristics of spring wheat in northwest irrigated areas, so as to provide a theoretical basis for optimizing the efficient use of water resources in spring wheat production.

A split-zone design was adopted, with two cropping patterns of multiple-cropping green manure (W-G) and post-wheat fallow (W) in the main zone, three N fertilizer levels in the sub-plot: conventional N fertilizer application (180 kg·hm^-2, N3), N fertilizer reduction of 15% (N2, 153 kg·hm^-2), and N fertilizer reduction of 30% (N1, 126 kg·hm^-2). The effects of multiple-cropping of green manure and nitrogen reduction on yield, water consumption and water use efficiency of spring wheat were studied from 2020 to 2021.

The multiple-cropping green manure combined with moderate reduction of nitrogen fertilizer increased the pre-sowing soil water storage of spring wheat, and W-G increased the pre-sowing soil water storage of spring wheat by 11.5% to 13.5% compared with W pattern, while the multiple-cropping green manure combined with N reduction of 15% (W-GN2) and multiple-cropping green manure combined with N fertilizer reduction of 30% (W-GN1) increased the pre-sowing soil water storage of spring wheat compared to control post-wheat fallow combined with conventional N fertilizer application (W-N3) by 12.1% to 20.2% and 15.2% to 16.6%, respectively. W-G reduced water consumption of spring wheat by 12.6% to 13.7% compared with W-GN1, and W-GN2 reduced water consumption of spring wheat by 15% compared to W-N2 and W-N3, respectively. W-G effectively harmonized the water demand characteristics of spring wheat before and after the reproductive period by reducing the evapotranspiration modulus coefficient of spring wheat at the early stage of nodulation and filling, and increasing the evapotranspiration modulus coefficient of pre-sowing to jointing and early-filling to maturity (the proportion of water consumption of the two stages to the total water consumption of the whole reproductive period was 60.5% to 64.1%). Finally, the synchronization of water supply and demand during the growth and development of spring wheat was enhanced. W-G had the advantage of yield increase, with 13.5% to 14.1% under W pattern. W-GN2 and W-N3 had yield increases of 16.7% to 18.4% and 13.6% to 14.6% under W-N2 and W-N3, respectively. Thus, W-G improved water use efficiency by 29.4% to 31.0% compared with the W pattern, and among the multiple-cropping green manure, W-GN2 improved water use efficiency by a greater extent than W-N2 and W-N3 by 44.2% to 46.8% and 39.1% to 43.5%, respectively, and W-GN1 and W-GN3 by 36.2% to 50.7% and 9.1% to 17.0%, respectively.

The multiple-cropping green manure combined with 15% N fertilizer reduction (i.e., 153 kg·hm^-2 of N fertilizer) improved spring wheat yield and water use efficiency compared with conventional water and N fertilizer management, and could be recommended as a production technique for efficient water use in spring wheat in dry irrigated areas.