Effects of Planting Date and Density on Plant Growth, Yield, Evapotranspiration, and Water Productivity of Subsurface Drip-Irrigated and Rainfed Maize

Abstract

Field maize ( L.) grain yield, evapotranspiration (ETc), and crop water productivity can be substantially impacted by planting population density (PPD) and planting date, depending on the location and crop, soil, and irrigation management practices. Field experiments were conducted in the 2011 and 2012 growing seasons to measure grain yield and quantify ETc, irrigation water use efficiency (IWUE), and crop water use efficiency (CWUE) as well as develop irrigation-yield production functions (IYPF) and evapotranspiration-yield production functions (ETYPF) for three PPDs and planting dates under subsurface drip irrigation and rainfed conditions in south central Nebraska. Plant growth and development indicators [leaf area index (LAI) and plant height] were quantified. Three PPDs [59,300, 74,100, and 88,900 plants per hectare (pph)] and three planting dates (May 4, 16, and 23 in 2011, and April 24, May 8, and May 17 in 2012) were implemented. Planting date and PPD had mixed effects on ETc, which ranged from 423 to 577 mm under irrigated conditions and from 355 to 501 mm under rainfed conditions. In 2011 under irrigated conditions, maize ETc increased with delaying the planting date under 59,300 PPD, while it decreased with delaying the planting date under 88,900 PPD. Under 74,100 PPD, the lowest ETc of 507 mm was observed for the 2nd planting (May 16), and the highest ETc of 563 mm was observed under late planting in 2011. In 2012, ETc varied from 466 to 577 mm under irrigated conditions and from 355 to 501 mm under rainfed conditions. Maize ETc decreased with delaying the planting date under 88,900 PPD, and the May 8 planting resulted in the lowest ETc under 74,100 PPD. The 59,300 PPD had the highest ETc with the May 8 planting. Based on the pooled data of all PPDs, every 10-day delay (relative to the 1st planting) in planting date in a wet year (2011) did not affect ETc and resulted in only a 1 mm increase in ETc (ETc = 0.0746 x DOY + 505.53), whereas in a dry year (2012) every 10-day delay resulted in a substantial increase in ETc of 26 mm (ETc = 2.5887 x DOY + 134.87) beyond the intercept. Overall, grain yield increased with increasing PPD relative to the 1st planting by 15.9%, 12.2%, and 12.7% for 59,300, 74,100, and 88,900 PPD, respectively, under irrigated conditions and by 7.7%, 2.9%, and 5.6% for the same PPDs, respectively, under rainfed conditions. Overall, the impact of planting date on grain yield varied with the PPD and year and with rainfed or irrigated conditions. However, in general, each one-day delay in the planting date (from May 4) resulted in an average yield increase of 0.043 ton ha-1 (yield = 0.0428 x DOY + 7.3104) in a wet year (2011), and each one-day delay in the planting date in 2012 (from April 24) resulted in an average yield increase of 0.056 ton ha-1 (yield = 0.0555 x DOY + 2.4753) beyond the intercept. In the dry year, the late planting under rainfed conditions resulted in a substantial yield decrease with increasing PPD, with 16% and 10% yield reductions under the 74,100 and 88,900 PPDs, respectively, relative to 59,300 PPD. IWUE varied from 1.20 kg m-3 for the 1st planting with 88,900 PPD to 5.12 kg m-3 for the 3rd planting with 88,900 PPD in 2011, and from 1.63 kg m-3 for the 1st planting with 59,300 PPD to as high as 5.22 kg m-3 for the 1st planting with 74,100 PPD in 2012. In both years, CWUE values were very similar between treatments, ranging from 2.27 kg m-3 for the 3rd planting with 59,300 PPD to 2.81 kg m-3 for the 1st planting with 59,300 PPD. The IYPF and ETYPF exhibited intra-annual and inter-annual variation between planting dates and planting densities.