Effects of cultivation methods and potash fertilizer on seed yield, qualityand potassium use efficiency of sunflower

Objectives Effects of potassium (K) application levels and different cultivation methods on seed yield and quality, and K fertilizer efficiency of sunflower were studied. The aim was to identify efficient and sustainable K nutrient management.

Methods The field experiment was conducted in north Yinshan area, Inner Mongolia, China, over a 2-year period (2014‒2016). Sunflower of 3638C for comsuming seeds was used as the test material. The experimental plots were mulched with plastic film. The sunflower was subjected to three different cultivation conditions planting in flat field without irrigation (R), planting in furrow between ridges without drip irrigation (RC), and planting in furrow between ridges with drip irrigation (I) and four K levels (0, 48, 84 and 120 kg/hm²). At harvest, the seed yield and yield components, the K contents in stalk, eeds, and soil were measured.

Results Water supply, which is affected by the cultivation method, was the main factor that affected sunflower seed yield and yield traits. The disc diameter, 1000-seed weight, seed kernel ratio, K uptake, potash fertilizer efficiency were all in order of I>RC>R. The seed yield, yield traits and K uptake increased with increase in K rate under I treatment, but did not change under R treatment. The utilization rate and agronomic efficiency of potash fertilizer decreased with increase in K rate in all the three cultivation conditions. K rate had significant effect on the seed oil content, especially the linoleic acid content. The basic K balance of soil under I, RC and R conditions were K₂O rate of 120 kg/hm², 84 kg/hm² and 48 kg/hm², respectively.

Conclusions Our results showed that furrow planting of sunflower is preferred to flat planting, especially under irrigation. For high seed yield, quality and potash fertilizer efficiency, and balanced soil K in north Yinshan area, Inner Mongolia, about 120, 84 and 48 kg/hm² of K₂O should be applied under furrow planting with irrigation, furrow planting without irrigation, and flat planting under rainfed condition, respectively.