Development of an assay to evaluate differences in germination rate among chickpea genotypes under limited water content

Abstract

An assay system that provides rapid and reproducible germination under low soil water content (<10% water holding capacity (WHC)) was developed and used to compare how chickpea (Cicer arietinum L.) genotypes complete germination, without the technical difficulties of accurately controlling water levels. The system consisted of small plastic containers (50 mm × 50 mm × 60 mm) filled with river sand and tightly closed (but not sealed) to minimise water loss and maintain constant soil water content during germination. Seed size influenced germination performance at low WHC. Small seeds within a single genotype germinated successfully and entered into the early stages of seedling growth, but germination of large seeds was inhibited, failing to germinate at 5% WHC. Small seeds were more efficient in remobilising seed reserves to seedling tissues than larger seeds. Under optimal WHC, the germination rate and subsequent radicle growth was similar among genotypes but at low WHC, there was variation despite seeds being of comparable size and imbibing equally. This suggests that the physiological threshold of threshold water potential for initiation of germination reflects genotypic differences. The assay system provides a suitable experimental tool to examine gene expression in contrasting genotypes during germination and early stages of seedling growth with a view to identifying the genes involved in superior performance under water limited field conditions.

Negative evidence of local adaptation to the establishment conditions in a perennial herb

“…Therefore, at Pine Forest, low values of Water Availability were related to low emergence probabilities. Similar results have been reported in several studies where low levels of Water Availability induced differences on germination success due to seed size (Saxena et al 1993;Kikuzawa and Koyama 1999;Vessal et al 2012). Thus, at low levels of Water Availability, while smaller seeds germinated successfully and entered into the early stages of seedling growth, germination of larger seeds resulted inhibited.…”

“…Thus, at low levels of Water Availability, while smaller seeds germinated successfully and entered into the early stages of seedling growth, germination of larger seeds resulted inhibited. This effect has been attributed to a higher efficiency of smaller seeds in re-mobilizing reserves to seedling tissues (Vessal et al 2012).…”

Breeding for improved drought tolerance in Chickpea (Cicer arietinum L.)

“…Germination initiation is delayed under limited water availability and proportional to imbibition time (Vessal et al. ).…”

“…Drought reduces soil osmotic potential which inhibits the germination and, at À0.8 MPa, germination was found to halt completely (Y€ ucel et al 2010(Y€ ucel et al , Sleimi et al 2013. Germination initiation is delayed under limited water availability and proportional to imbibition time (Vessal et al 2012).…”

​Screening of Chickpea (Cicer arietinum L.) Genotypes for Germination and Early Seedling Growth under PEG 6000 Induced Drought Stress

“…Drought reduces soil osmotic potential that inhibits the germination which was found to halt completely at -0.8 MPa (Yucel et al 2010;Sleimi et al 2013). Germination initiation is delayed under limited water availability due to prolonged imbibition time (Vessal et al 2012). Lack of sufficient soil moisture effects the establishment of the seedlings leading to seedling mortality.…”