Effects of plant density and nitrogen rate on lodging-related stalk traits of summer maize

Abstract

Stalk lodging is a major constraint to limit grain yield under increased planting density in modern maize (Zea mays L.) production. A 3-year field experiment was imposed to study the effects of plant density and nitrogen (N) rate on stalk lodging and lodging-related stalk traits of two maize hybrids of contrasting susceptibility to lodging. The results indicated that the stem diameter, rind penetration strength (RPS), bending strength (BS), rind thickness, vascular bundle sheath's thickness (Vbs) and number of vascular bundle (Vb) of both hybrids all significantly decreased at the high density, while ear height and ear ratio clearly increased in Ludan981 (LD981; lodging-susceptible cultivar) with plant density increase. The lower plant height and ear height, stronger RPS and BS, and more Vb at high plant density might be reasons for Zhengdan958 (ZD958, lodging-resistant cultivar) had lower rate of stalk lodging. Meanwhile, N supply can significantly improve the stalk quality and decrease the risk of stalk lodging, however, little effects were observed in cv. LD981. Therefore, using lodging-resistant cultivar, planting at 82 500 plant/ha and supplying 180 kg N/ha can obtain high grain yield and low stalk lodging.Keywords: maize lodging; lodging resistance; mechanical property; microstructure 299Plant Soil Environ. Vol. 62, 2016, No. 7: 299-306 24.55, 26.35, and 25.42°C and 247.7, 225.4, 236.1 mm in 2013, 2014 and 2015. For this study, Zhengdan958 (ZD958, lodgingresistant cultivar) and Ludan981 (LD981, lodgingsusceptible cultivar), were used for experimental materials. Two plant densities (D1 -52 500, D2 -82 500 plants/ha), and three N rates (N0 -0, N120 -120, N180 -180 kg N/ha as urea) were conducted for the two cultivars. The experiments were established in a split-plot design of three replicates (36 subplots), with cultivar as the main plot, with density and nitrogen rate as the sub-plot. These subplots were arranged randomly and the size of each subplot was 15.0 m × 3.0 m (rows spaced 60 cm apart).Basal fertilization of each subplot was applied before tillage during both years; it included phosphorus as calcium superphosphate and potassium as chloride at the rate of 53 kg P/ha and 119 kg K/ha, respectively. The N fertilizer source was half applied at the sixth leaf stage (V6) and half at the twelfth leaf stage (V12). The seeds were sown on 17 June and harvested on 5 October in each test year. Water, weeds, insects, and diseases were controlled as required to avoid yield loss.Grain yield. In this experiment, thirty successive ears were hand harvested from the centre rows of each plot at physiological maturity (R6). Grains of all harvested ears were separated manually from cobs and weighed to determine the average individual yield. The grain yield per hectare was the product of ear density and average individual yield.Stalk lodging estimates. All plants that bent and broke in the central three rows of each plot were counted to calculate stalk lodging at R6. Stalk lodging was the ratio of the num...

Optimizing N Fertilization for Increasing Yield and Profits of Rainfed Maize Grown under Sandy Loam Soil

“…A decrease in plant lodging from an increasing N dose might be due to an increase in the activity of the key enzymes regulating the lignin biosynthesis, lignin content, and stalk diameter [53,59]. Moreover, the thickness of the rind number and thickness of the vascular bundle is negatively correlated to stalk lodging [53]. As in our study, significant low stalk lodging was reported in maize at 120 kg ha −1 N and a similar plant density [53].…”

“…Moreover, the thickness of the rind number and thickness of the vascular bundle is negatively correlated to stalk lodging [53]. As in our study, significant low stalk lodging was reported in maize at 120 kg ha −1 N and a similar plant density [53]. Additionally, they reported, N application increased stem characteristics such as rind thickness, number, and thickness of vascular bundle and found a similar effect at 120 kg ha −1 N and 180 kg ha −1 N.…”

“…Lower Leaf senescence with increasing N doses could be due to prolonged green color photosynthetic tissues (Figure 3). Shi et al [53] reported that plant and ear height were similar when an N dose of 120 kg ha −1 or above was applied. Ding et al [54] found that dry matter production in N deficient plants was significantly lower than that of N supplied plants, particularly after flowering.…”

“…The low supply of N was evident as higher leaf senescence scores were recorded from such plots (Figure 3). A decrease in plant lodging from an increasing N dose might be due to an increase in the activity of the key enzymes regulating the lignin biosynthesis, lignin content, and stalk diameter [53,59]. Moreover, the thickness of the rind number and thickness of the vascular bundle is negatively correlated to stalk lodging [53].…”

Plant density and nitrogen topdressing of high-altitude main-season corn

“…Under this condition, plants invest more resources in elongation in an attempt to outgrow the crop canopy to escape shading and consequently have a reduced stem diameter (Taiz & Zeiger, 2017). In this situation, N supply can improve the stem quality and decrease etiolation caused by higher plant densities, although only up to a certain point (Shi et al, 2016), as observed in growing season 2 (Figure 2D).…”