This study aimed to explore the effects of combining new bio-breeding insect-resistant varieties with dense-planting precision-controlled high-yield technology on maize yield and economic benefits, and to propose the optimal cultivation mode suitable for new bio-breeding insect-resistant varieties, so as to provide the theoretical basis for optimizing the high-yield and high-efficiency cultivation system of spring maize in the Xiliaohe Plain.

Through a field trial in Tongliao, Inner Mongolia from 2023 to 2024, the experiment was conducted in a split-zone design, with cultivation mode as the main zone, setting up two modes of local traditional farmer mode (FP) and dense planting precision regulation mode (DPDI); varieties as the sub-zone, four maize varieties were used, namely, Dongdan 1331 (DD1331), Dongdan 1331K (DD1331K), Youdi 919 (YD919), Youdi 919HZ (YD919HZ). Then, the impact of varietal insect resistance traits on maize yield and economic benefits under different technical models were analyzed.

During a two-year trial, the insect pests in the fields of insect-resistant varieties occurred lightly, with the insect plant rate of 6.80%-9.87%; the fields of conventional varieties occurred moderately or heavily, with the insect plant rate of 22.27%-36.31%. In 2023 (insect plant rate>30%), compared with conventional varieties (DD1331, YD919), the new insect-resistant varieties (DD1331K, YD919HZ) significantly increased thousand kernel weight, thus improving maize yield (0.84%-9.31%) and economic benefits (0.3%-13.3%), whereas in 2024, when the insect plant rate was about 23%, there was no significant difference in the number of thousand kernels and the number of grains between insect-resistant varieties, and there were no significant differences in ear grain number, thousand kernel weight and yield between conventional varieties. With increasing planting density, maize yield reached its maximum at 9.0×10⁴ or 10.5×10⁴ plants/hm², which was significantly higher than that at 6.0×10⁴ plants/hm² density, by 13.54%-19.94% and 7.48%-21.01%, respectively. The two-year average yields of the dense planting precision regulated model were significantly higher than those of the traditional farmers' model, with yield increases ranging from 13.50% to 19.19% in 2023 and from 7.03% to 14.42% in 2024. Compared with the traditional farmers' model, the economic benefits of the dense planting precision regulation model were generally improved by 0.19×10⁴-1.02×10⁴ yuan/hm².

Insect-resistant varieties (DD1331K, YD919HZ) significantly improved yield (up to 9.31%) and economic efficiency (up to 40.3%) in years of severe insect infestation (>30% of insect plants), but did not differ significantly from conventional varieties under low insect pressure. Through optimized density (9.0×10⁴-10.5×10⁴ plants/hm²) and precise management of water and fertilizer, DPDI increased yields by an average of 22.18% in two years and improved economic benefits by 0.57×10⁴ yuan/hm² compared with the conventional mode (FP); the core principle of DPDI was that insect resistant varieties could reduce the threat of pests, decrease yield losses, reduce the use of insecticides, and lower production input costs. By increasing the production capacity of maize populations through reasonable planting density and combining drip irrigation with water and fertilizer integration for precise regulation, the yield and income of maize could be increased. The synergistic application of insect-resistant varieties and DPDI model could achieve technological superposition and further improve the ability of high and stable yield.

Reasonable increase of planting density and row spacing configuration is an important way to achieve high yield and high efficiency of maize. In order to provide the technical basis for high yield and high efficiency cultivation of drip irrigation maize in sandy land, the effects of dense planting and row spacing configuration on maize yield and water and fertilizer utilization efficiency in sandy land were studied under drip irrigation condition in Xiliaohe Plain.

Field experiments were carried out in Naiman Banner of Inner Mongolia in 2023 and 2024, and 'Zhengdan 958' was used as the test maize variety. Two planting densities: 60 000 plants/hm² (D1) and 90 000 plants/hm² (D2) and seven row spacing treatments: 60 cm+60 cm (L₆₀₊₆₀, CK), 40 cm+ 80 cm (L₄₀₊₈₀), 30 cm+90 cm (L₃₀₊₉₀), 30 cm+80 cm (L₃₀₊₈₀), 40 cm+70 cm (L₄₀₊₇₀), 30 cm+70 cm (L₃₀₊₇₀) and 20 cm+70 cm (L₂₀₊₇₀) were set. The effects of planting density and row spacing on maize yield, dry matter production, photosynthetic performance and water and nitrogen use efficiency under drip irrigation in sandy land were systematically analyzed.

Planting density and row spacing significantly affected the grain yield and water and nitrogen use efficiency of drip-irrigated maize in sandy land. In the two-year experiment, L₃₀₊₇₀ and L₃₀₊₈₀ obtained higher yield under D2 density, which were 15.6 and 15.5 t·hm^-2, respectively. The water use efficiency (WUE) reached 2.57 and 2.55 kg·m^-3, respectively, and the partial factor productivity of nitrogen fertilizer (PFP_N) reached 57.8 and 57.2 kg·kg^-1, respectively. Among them, the yield difference between L₃₀₊₈₀ and L₃₀₊₉₀ in 2023 did not reach a significant level, and the yield was 18.2% and 17.0% higher than that of L₆₀₊₆₀, respectively. The dry matter accumulation at silking stage (DMAS), dry matter accumulation at maturity stage (DMAM), dry matter accumulation after anthesis (DMAAS) and harvest index (HI) increased by 49.5%, 75.0%, 97.6%, 18.3% and 45.1%, 73.3%, 96.8%, 19.3% compared with L₆₀₊₆₀, respectively. The total photosynthetic potential increased by 33.6% and 30.1% compared with L₆₀₊₆₀ during the growth period. The light transmittance (Tr) of the bottom layer and ear layer decreased by 51.7%, 27.5% and 37.9%, 20.9% compared with L₆₀₊₆₀, respectively. The photosynthetic rate (Pn) of ear leaf at silking stage (R1) and maturity stage (R6) increased by 61.0%, 60.3% and 61.5%, 59.4%, respectively. WUE and PFPN increased by 19.7%, 17.8% and 21.1%, 16.8% compared with L₆₀₊₆₀, respectively. In 2024, there was no significant difference in yield between L₃₀₊₇₀ and L₃₀₊₈₀, which was 14.3% and 13.8% higher than that of L₆₀₊₆₀, respectively; DMAS, DMAM, DMAAS and HI increased by 56.6%, 87.0%, 118.4%, 28.9% and 52.1%, 81.0%, 114.6%, 29.0%, respectively; the total photosynthetic potential increased significantly by 65.9% and 63.0% during the growth period, respectively; the Tr of the bottom layer and the ear layer decreased by 53.8%, 24.9% and 52.1%, 22.8%; the Pn of ear leaf of R1 and R6 increased by 18.7%, 86.6% and 65.6%, 86.2%, respectively. WUE and PFP_N increased by 18.7%, 13.6% and 18.9%, 14.1%, respectively. Correlation analysis showed that maize yield was significantly positively correlated with 1000-grain weight, grain number per spike, number of harvested spikes, HI, WUE and PFP_N. DMAS and DMAAS were significantly positively correlated with grain number per spike, 1000-grain weight, LAD before anthesis, LAD after anthesis and Pn, and negatively correlated with Tr.

Under the condition of drip irrigation and fertilizer integration in the sandy land of Xiliaohe Plain, the interaction between planting density and row spacing mainly affected the grain yield and water and nitrogen use efficiency of maize by affecting the light transmittance of maize population, leaf photosynthetic capacity, dry matter accumulation and LAD. Therefore, the high yield and water and nitrogen production efficiency could be obtained by reasonably increasing the density of high-yield varieties to 90 000 plants/hm² and wide-narrow row spacing of 30 cm+70/80 cm.