Dispersal unit morphology， and effects of burial depth on seed germination and emergence of Stipa sareptana

doi:10.11686/cyxb2024230

Abstract

Abstract:

Stipa sareptana， a perennial herb of the Poaceae， is an important community constructive and dominant species widely distributed in desert grassland of Xinjiang. This research studied the morphology of the dispersal unit， the function of the awn and the germination and emergence characteristics of S. sareptana seeds. The relationship between the morphology of each part of the dispersal unit and the buried depth was analyzed， and the effects of different burial depths on seed germination and seedling emergence were compared. The results show that： 1） The dispersal unit is composed of lemma， palea and caryopsis. The base of the lemma is sharp and hairy with an anchoring capability. The lemma elongates to form an awn， and the elongated body of the awn is typically doubly bent. The length of the awn is 15 times than that of the seed. 2） The awn is hygroscopic， and the hygroscopic awn drives a self-burial phenomenon of the dispersal unit. The burial depth achieved is （4.10±0.53） cm. 3） Burial depth had a very significant effect on the seed germination percentage and seedling emergence percentage of S. sareptana seeds （P<0.01）. The seeds germinated in the depth range of 0-12 cm， and emerged from depths <6 cm. The seed germination percentage and seedling emergence percentage were highest when the burial depth was 1-2 cm. When the burial depth exceeded 2 cm， the seed germination percentage and seedling emergence percentage were negatively correlated with the burial depth. 4） The burial depth had a significant effect on the growth and biomass allocation of S. sareptana seedlings （P<0.01）. When the buried depth increases， S. sareptana seedlings allocate more biomass to upward growth， thus promoting the growth of shoots above ground. The plasticity of biomass distribution is an important mechanism for S. sareptana to adjust to variation in burial depth. The unique dispersal unit structure of S. sareptana not only enhances the survival of seeds entering the soil， but also greatly improves the success rate of seed germination and subsequent seedling establishment. These seed properties are highly advantageous to the renewal and reproduction of S. sareptana populations.

Key words: Stipa sareptana, dispersal unit, awn, hygroscopic, seed germination, seedling emergence

Yu-qi ZHENG, Jia-yue YAN, Bo-yuan LI, Yan WEI. Dispersal unit morphology， and effects of burial depth on seed germination and emergence of Stipa sareptana[J]. Acta Prataculturae Sinica, 2025, 34(5): 64-73.

Figures/Tables 9

Fig.1 The maximum and minimum daily temperature in Urumqi from August to September in 2023

Fig.2 Morphological structure of dispersal unit of S. sareptana

Fig. 3 Morphological characteristics of all parts of S. sareptana

Fig.4 The hygroscopic awn movements

Fig.5 The germination process of S. sareptana under the same buried depth

Table 1 Growth and morphology of different parts of the seedlings of S. sareptana

播种后天数 Days after sowing （d）	幼苗不同部位长度The length of each part of the seedling （cm）
播种后天数 Days after sowing （d）	根Root	第一节间First internode	胚芽鞘Coleoptile	芽Shoot
3	0.91±0.21c	0.11±0.08b	0.30±0.14c	0
6	1.63±0.15bc	0.16±0.06a	1.28±0.31b	0.29±0.26d
9	2.06±0.34b	0.18±0.07a	1.96±0.22a	0.65±0.48c
12	2.24±0.33b	0.20±0.05a	2.05±0.12a	1.02±0.33b
15	3.77±0.19a	0.20±0.04a	2.02±0.21a	1.61±0.13a

Fig.6 Effect of different burial depth on seeds germination rate and seedling emergence rate of S. sareptana

Fig.7 Effect of different burial depths on the cumulative emergence rate of seeds of S. sareptana

Fig.8 Effects of different burial depths on roots， first internode， coleoptile and shoot length of S. sareptana

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