Chilling stress is one of the major abiotic stresses affecting waxy maize plant growth. Melatonin (MT) is able to improve tolerance to abiotic stress in plants. To investigate the effects of seed priming with MT on tolerance to chilling stress in waxy maize, the seed germination characteristics and physiological parameters were tested with varied MT concentrations (0, 50, 100 µM) and treatment times (12, 24 h) at ambient (25 °C) and chilling (13 °C) temperature. MT primed seeds significantly enhanced the germination potential (by 20.29% and 50.71%, respectively), germination rate (by 20.88% and 33.72%), and increased the radicle length (by 90.73% and 217.14%), hypocotyl length (by 60.28% and 136.14%), root length (by 74.59% and 108.70%), and seed vigor index (46.13%, 63.81%), compared with the non-priming seeds under chilling stress. No significant difference was found in priming time between primed and non-primed seeds. In addition, lower H₂O₂ and malondialdehyde concentrations, increased antioxidant enzyme activities (superoxide dismutase, peroxidase, catalase and ascorbateperoxidase), and promoted starch metabolism were found in primed seeds compared to non-primed ones. It was suggested that seed priming with MT improved waxy maize seed germination under chilling stress through improving antioxidant system and starch metabolism, which protected from oxidative damage.

Conservation management is necessary to ensure soil sustainability. We investigated the response of soil chemical, biological properties, and bacterial community to 11 years of different mulch and tillage practices in an aeolian sandy soil in a maize continuous cropping system. Treatments included: no-till + straw coverage (ZT+R), rotary tillage + straw coverage (RT+R), and normal tillage (CT). Compared to CT, ZT+R and RT+R significantly increased total organic carbon (TOC) content, C:N ratio, available nitrogen (AN) content, and acid phosphatase (ACP) and urease activities, while decreasing soil pH in topsoil and subsoil. Moreover, RT+R enhanced C:N ratio and AN content and ACP and urease activities in deep soil. ZT+R increased bacterial richness and diversity; dominant phyla of Actinobacteria and Acidobacteria were found in topsoil and Gemmatimonadetes in subsoil and deep soil. However, RT+R showed negative effects on soil bacterial diversity and bacterial community because of severe soil disturbance. Redundancy analysis revealed that soil chemical properties (pH and TOC) are closely associated with soil bacterial communities. Therefore, long-term land management plays an important role in shaping microbial functional profiles. ZT+R is optimum for the enhancement of soil chemical properties and bacterial communities of aeolian sandy soils with a continuous cropping system.

This study aims to investigate the responses of carbon assimilation, grain yield, leaf stay-green rate, nitrogen uptake and distribution to soil compaction in the hard plow pan caused by repeated use of tractor-driven cultivator in Northeast China. The typical hybrid maize variety “Zhengdan 958” was exposed to two treatments of simulated plow pan (SP) and simulated subsoiling (SS, control) in pot experiments from 2012 to 2014. Compared with SS, SP significantly reduced net photosynthetic rate (Pn) during growth stage, leading to a decrease in dry matter accumulation (DMA) and grain yield (GY) in three consecutive experimental years. Leaf stay-green degrees (LSD), which showed a fast descending trend from 20 days after silking (DAS), significantly decreased in the later filling stage under SP treatment. The translocation efficiency of the stored N (TEN) in stalk and leaf to the grain during pre-silking was enhanced, whereas leaf and grain N concentration (LNC/GNC), together with N accumulation amounts at maturity were significantly reduced under SP treatment. Also, plough pan reduced the N distribution to the organs of stalk, leaf and grain. In conclusion, subsoiling is a possible way to delay leaf senescence and achieve higher DMA and GY, and increased grain N in the corn belt of Northeast China.

Delayed sowing (DS) is a critical factor influencing grain yield and quality under climate change. This study was conducted to determine maize grain yield and quality traits responses to DS and varied genotypes in rain-fed condition, northeast of China. Two typical hybrids ZD958 (higher starch type) and LM33 (higher protein type) and three sowing dates: 30 April (DS0) as normal, 10 May (DS10) and 20 May (DS20) were compared. Results demonstrated maize grain yield, biomass, kernel number per square, thousand kernel weight (TKW), grain nutrition yield, N concentration and grain test weight were significantly reduced by DS. Compared to high protein type LM33, high starch type ZD958 had a higher yield potential and lower yield reduction with delayed sowing. Grain yield loss under DS could be mainly attributed to reduction of the BMP and biomass, thereby leading to the reduction of TKW and kernels number per unit. DS didn’t affected grain nutritional content (starch, protein and oil), while significantly reduced grain nutrition yield of starch, oil and protein with delayed sowing. This study suggests that, early sowing should be recommended to the framers and varieties adjustments maybe a possible approach to reduce and compensate for the loss of yield caused by delayed sowing in rain-fed condition under climate change in NCP.