Agronomy and Horticulture Department


First Advisor

Cody Creech

Second Advisor

Amanda Easterly

Date of this Version



Orazov, Z. (2022). Addressing challenges of dryland production of sunflowers and corn in the semi-arid high plains of Nebraska [Master's thesis]. University of Nebraska-Lincoln.


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Agronomy, Under the Supervision of Professors Cody Creech and Amanda Easterly. Lincoln, Nebraska: December 2022

Copyright © 2022 Zhan Orazov


Corn and sunflower are value crops for America. Cultivation of corn and sunflower often vary depending on growing environment. Selecting appropriate planting dates, hybrids and plant density frequently concerns farmers. This concern is understandable because the decision made directly impacts final income. The objectives were to evaluate interaction of corn and sunflower planting dates and hybrid maturity and evaluate interaction of corn flex hybrids and plant density under conditions of western Nebraska. Nine corn hybrids with relative maturity ranging from 86 to 105 days were sown between early May and late June in first and between late April and early June in second year of study at the High Plains Agricultural Laboratory near Sidney NE in 2021 to 2022. The optimal planting date to achieve maximum grain yield was early May in the first year and over 50% decrease of grain yield was observed when planting date was delayed from early May to late June. In the second-year planting dates had no significant variation in terms of grain yield while corn planted later than May failed to yield. Variation among hybrids in terms of grain yield was not significant in 2021 while in 2022 hybrid NK 0440 had an 85% decrease in yield in contrast to DKC 36-86 RIB. Three sunflower hybrids with relative maturities of 89, 94 and 98 days were sown between 9 May and 24 June at the High Plains Agricultural Laboratory near Sidney NE in 2021 to 2022. Sunflower planted in early May achieved maximum grain yield and 64% decrease of grain yield occurred when planting date was delayed from early May to late May. Early maturing hybrid averaged across all planting dates indicated 70 percent greater grain yield than the medium maturity hybrid. Four corn hybrids with different ear flex characteristics were planted at 19,768; 27,181; 34,595; 42,007; and 49,420 plants per hectare populations in Nebraska, one near Sidney and the other in Box Butte County from 2021-2022. A plant population of 34,595 achieved greatest grain yield in 2021. When population was increased from 34,595 to 42,007 grain yield decline on 12% was observed. In 2022, grain yield varied significantly by hybrids. Hybrids CP 3337 and DKC 42-04 RIB had greatest grain yield of 2,295 and 2,271 kilograms per hectare. CP 3337 produced in average 32 percent secondary ears greater than all hybrids.

Advisors: Cody F. Creech and Amanda C. Easterly