Effects of Irrigation and Nitrogen Fertilization on Seed Yield, Yield Components, and Water Use Efficiency of Cleistogenes songorica

Qibo Tao,Cunzhi Jia,Yunhua Han,Mengjie Bai,Yanrong Wang

doi:10.3390/agronomy11030466

Qibo Tao, Cunzhi Jia + Show 3 more

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https://doi.org/10.3390/agronomy11030466

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Abstract

Irrigation and nitrogen (N) are two crucial factors affecting perennial grass seed production. To investigate the effects of irrigation and N rate on seed yield (SY), yield components, and water use efficiency (WUE) of Cleistogenes songorica (Roshevitz) Ohwi, an ecologically significant perennial grass, a four-year (2016–2019) field trial was conducted in an arid region of northwestern China. Two irrigation regimes (I1 treatment: irrigation at tillering stage; I2 treatment: irrigation at tillering, spikelet initiation, and early flowering stages) and four N rates (0, 60, 120, 180 kg ha−1) were arranged. Increasing amounts of both irrigation and N improved SY, evapotranspiration, WUE, and related yield components like fertile tillers m−2 (FTSM) and seeds spikelet−1. Meanwhile, no significant difference was observed between 120 and 180 kg N ha−1 treatments for most variables. The highest SY and WUE was obtained with treatment combination of I2 plus 120 kg N ha−1 with four-year average values of 507.3 kg ha−1 and 1.8 kg ha−1 mm−1, respectively. Path coefficient and contribution analysis indicated that FTSM was the most important yield component for SY, with direct path coefficient and contribution coefficient of 0.626 and 0.592. Overall, we recommend I2 treatment (three irrigations) together with 120 kg N ha−1 to both increase SY and WUE, especially in arid regions. Future agronomic managements and breeding programs for seed should mainly focus on FTSM. This study will enable grass seed producers, plant breeders, and government program directors to more effectively target higher SY of C. songorica.

Highlights

Cleistogenes songorica (Roshevitz) Ohwi is a perennial Poaceae grass native to temperate arid, semi-arid, and desert areas of central Eurasia including northern China, Kazakhstan, Kyrgyzstan, Russia, Turkmenistan, Uzbekistan, and many other countries [1]
When the means of fertile tillers m−2 (FTSM) and seeds spikelet−1 (SS) were compared between four N rates, we found that increasing N dose promoted positive effects, but no significant difference was recorded between 120 and 180 kg N ha−1 treatments
It has been reported that grass seed crops are very sensitive to water-deficit stress during reproductive periods like anthesis and seed setting stages, strategic irrigation to support these critical stages is beneficial for improving seed yield (SY) [13]

Summary

Introduction

Cleistogenes songorica (Roshevitz) Ohwi is a perennial Poaceae grass native to temperate arid, semi-arid, and desert areas of central Eurasia including northern China, Kazakhstan, Kyrgyzstan, Russia, Turkmenistan, Uzbekistan, and many other countries [1]. It is the dominant species in desert grasslands where annual precipitation is around 120 mm, with significant ecological value (Figures S1 and S2) [2]. Because of a strong root system and excellent resistance to stress environments including drought, C. songorica has been considered as one of the most promising plant species for desert ecosystem and degraded grassland restoration [3,4]. The most practicable method to optimizing SY is to choose an appropriate seed production region and optimize the field agronomic managements used [11]

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