Effects of microscopic testa color and morphologyon the water uptake ability and drought tolerance of germination-stage rapeseed (Brassica napus L.)

ABSTRACT

Drought is one of the most important abiotic stressors that affect crop yield. Therefore, the aim of the present study was to investigate correlations between germination-stage drought tolerance and the microscopic testa (i.e., seed coat) characteristics (color and papilla morphology) and imbibition abilities of 35 rapeseed (Brassica napus L.) accessions. After 2 h imbibition, seed water uptake (fresh weight increase) was significantly positively correlated with testa hue (H_HSB), brightness (B_HSB,), blue (B_RGB), and lightness (L*), with correlation coefficients of 0.38, 0.34, 0.53, and 0.36, respectively, and significantly negatively correlated with saturation (S_HSB), greenness-redness (a*), blueness-yellowness (b*), magenta (M), and yellow components (Y), with correlation coefficients of −0.53, −0.40, −0.53, −0.39, and −0.55, respectively. Furthermore, 5-h seed water uptake was significantly positively correlated with number of papillae (No.P), mean papillae area (APA), the papillae area ratio (PAR), gray value of red channel of papillae, with correlation coefficients of 33, 0.36, 0.43, and 0.43, respectively. Under drought conditions, genotypes with more rapid water absorption exhibited higher germination rates and stronger drought tolerance, and the germination rate and drought tolerance of black-seeded accessions were highest, followed by red-seeded accessions and then yellow-seeded accessions, which exhibited the lowest germination rate and drought tolerance. Germination rate was significantly negatively correlated with B_RGB, H_HSB, L*, D_g, and D_b and significantly positively correlated with S_HSB and Y, regardless of drought conditions. At the germination stage, D_bTP was negatively correlated with drought tolerance.

KEYWORDS:

• Drought
• imbibition
• papillae
• seed coat
• seed color
• testa

Acknowledgements

We are grateful to Prof. Xue kun Zhang for his advice and suggestions.

Disclosure statement

The authors declare that they have no conflict of interest that could be perceived to influence the results or discussion of this manuscript.

Authors’ contributions

ZHZ, MF, and AS designed and performed the experiment and wrote the manuscript; WYZ, ZPC, XZJ, HZ, YL, and YY analyzed the data; and ZHZ and KJZ provided guidance during all experiments. All authors have read and approved the manuscript.

Supplementary Material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the Natural Science Foundation of Anhui Province under Grant 1908085MC68 and the National Key Technology Research and Development Program under Grant 2018YFD0100600