Responses of hypocotyl growth and seedling emergence with respect to soil sowing depth stress in peanut (Arachis hypogaea L.)

ABSTRACT

Optimal sowing depth plays an important role in peanut’s stand establishment and yield. A field experiment was conducted to investigate sowing depths effects (3 cm, SD₃; 5 cm, SD₅; 7 cm, SD₇; 9 cm, SD₉; 11 cm, SD₁₁; 13 cm, SD₁₃; 15 cm, SD₁₅) on soil environments, hypocotyl growth, endogenous hormones content, and pod yield. Both shallow- (3 cm) and deep-sowing (15 cm) treatments decreased the pod yield due to plant and pod number lowering that resulted from decreased seedling emergence rate (SER). SD₃ treatment possessed less soil water content (SWC) that led to lowered SER. Soil penetration resistance (SPR) was significantly increased with sowing depths that resulted in SER decrease and delayed emergence time. Compared with the SD₅ treatment, the SER was 15.7% and 16.6% lower in SD₁₅ treatment in the 2017 and 2018 season, respectively. SD₅ and SD₁₅ took 111.1 and 161.5 day-degrees (°Cd), respectively; to attain maximum length. Further, sowing depth increase resulted in elevated cotyledon’s lipase activities, endogenous auxin (IAA) and gibberellin (GA₃) contents, and hypocotyl dry weight. However, decreased cotyledon weight implied that hypocotyl growth of deep-sowing exhausted the stored nutrition by increasing endogenous GA₃ and IAA, to sustain its emergence above the soil.

KEYWORDS:

• Hypocotyl length
• soil penetration resistance
• endogenous hormones
• thermal time
• peanut yield

Disclosure statement

No potential conflict of interest was reported by the authors.

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Additional information

Funding

This research was supported by the National Key Research and Development Program of China [Grant No. 2018YFD1000900], the Shandong Key Research and Development Program [2018YFJH0601-3], the Major Agricultural Applied Technological Innovation Projects in Shandong Province [Grant No. SD2019ZZ11], and the Shandong Modern Agricultural Technology and Industry System [Grant No. SDAIT-04-01].