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

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.

Effect of ammonia-oxidizing bacterial strain that survives drought stress on corn compensatory growth upon post-drought rewatering

“…Similarly, most crop irrigation is also a process of post-drought rewatering. The irrigation is usually accompanied by nitrogen fertilizer application to increase the crop water use efficiency (Tao et al, 2021 ; Zain et al, 2021 ). The coexistence of soil heterotrophic AOB with crops can increase the timely irrigation water use, which plays a potential role in replacing nitrogen fertilizer.…”

Cleistogamous spike and chasmogamous spike carbon remobilization improve the seed potential yield of Cleistogenes songorica under water stress

“…Similarly, the WS treatment applied in C. songorica enhanced carbon remobilization in the sources and increased the seed yield per spike by increasing the seed number per spike (CL spikes and CH spikes), especially in CL_B spikes and CL_M spikes, where it increased 2.25 and 1.6 times, respectively. The seed number was one of the components of seed yield, and seed yield per plant was improved when the seed number per spike was increased (Li et al, 2014; Tao et al, 2021). Therefore, a well-controlled balance between source and sink at the initial flowering stage was pivotal for C. songorica production under the WS treatment.…”

“…However, the seed supply is insufficient due to the low seed yield of C. songorica , which limits its large-scale application in many fields, such as ecological restoration and grassland development (Li et al, 2014; Tao et al, 2018). Previous studies have shown that irrigation at the early flowering stage is an important aspect of successful seed production (Tao et al, 2021). However, the potential role of gene regulation in the WS-induced improvement of carbon reserve remobilization from source (stems, leaves and sheaths) sites, and the interaction between sources, CL spikes and CH spikes at the transcriptional level is not clear in C. songorica .…”