Screening Oat Genotypes for Tolerance to Salinity and Alkalinity

Abstract

A set of four experiments was conducted to develop methods for screening oat tolerance to salt and alkali and the following results were obtained. (1) In experiment 1, 68.5 mmol L^-1 salt and 22.5 mmol L^-1 alkali were identified as appropriate concentrations for determining oat tolerance to salinity and alkalinity during germination. (2) These concentrations were used in experiment 2 to screen 248 oat genotypes and 21 were identified to be tolerant to salinity and alkalinity in germination. (3) In experiment 3, one salt treatment, 40 L of Na₂SO₄:NaCl (1:1), 150 mmol L^-1, was found to be optimal for screening oat tolerance to salinity during growth and development. For alkalinity tolerance, the optimal treatment was 40 L of Na₂CO₃:NaHCO₃ (1:1) at 75 mmol L^-1. (4) No significant correlation was found between tolerances at the germination and adult stages or between tolerances to salt and alkali. Three lines were found to be tolerant to both salt and alkali in both germination and adult stages. (5) In experiment 4, 25 out of 262 oat genotypes were found to be tolerant to both salinity and alkalinity. (6) GGE biplot analysis was found to be effective in interpreting the multivariate data and the plastic cone-container system was found to be cost-effective system for screening adult plant tolerance to salt and alkali. (7) The symptoms of salt stress and alkali stress were found to be different; alkali stress mainly reduces the chlorophyll content, while salinity mainly disrupts water absorption.

Keywords: GGE-biplot; alkali tolerance; cone-tainer; oat; salt tolerance; screening method.

FIGURE 1

The cone-tainer planting system.

FIGURE 2

Number of seeds germinated (out of 50) under different levels of salinity (A) and alkalinity (B) for four different oat cultivars: AC Bradley, AAC Bullet, AC Dieter, AAC Nicolas.

FIGURE 3

Relationship among germination rates under a salt stress and alkali stress across genotypes. The germination rate was represented both in number of germinated seed and in percentage of the control.

FIGURE 4

The similarity/dissimilarity in genotypic diffidences in grain set under 9 levels of salt stress (treatments 2 to 10) and 6 levels of alkali stress (treatment 11 to 16) plus the control (treatment 1). See Table 2 for descriptions of the treatments.

FIGURE 5

Ranking the 262 genotypes based on their tolerance (in terms of number of grains produced) across the salt and alkali stresses.

FIGURE 6

Appearance of oat plants under salt and alkali stresses. (A–C) salt stress. (D–F) alkali stress. (A) Oat under l00 mmol L^-1 salt stress. (B) Oat under 150 mmol L^-1 salt stress. (C) Oat under 200 mmol L^-1 salt stress. (D) Oat under 50 mmol L^-1 alkali stress. (E) Oat under 75 mmol L^-1 alkali stress. (F) Oat under l00 mmol L^-1 alkali stress.

FIGURE 7

Plant height of a single genotype under varied salt and alkali stresses. 2–7, salt stress; 8–13, alkali stress. 1, Control; 2 and 3, oat under l00 mmol L^-1 salt stress; 4 and 5, oat under 150 mmol L^-1 salt stress; 6 and 7, oat under 200 mmol L^-1 salt stress; 8 and 9, oat under 50 mmol L^-1 alkali stress; 10 and 11, oat under 75 mmol L^-1 alkali stress; 12 and 13, oat under l00 mmol L^-1 alkali stress.

FIGURE 8

(A) The effects of salt and alkali stresses on the number of dry leaves for 43 oat genotypes. (B) The effects of salt and alkali stresses on chlorophyll contents for 43 oat genotypes. J50, 50 mmol L^-1 alkali stress; J75, 75 mmol L^-1 alkali stress; Y100, 100 mmol L^-1 salt stress; Y200, 200 mmol L^-1 salt stress.

FIGURE 9

(A) The DNY leaves under salt stress. (B) The YND leaves under alkali stress. DNY leaves = dry but not yellow. YND leaves = yellow but not dry.

FIGURE 10

Effects of 16 treatments on the DNY leaves for 43 oat genotypes. See descriptions for each treatment in Table 1. DNY leaves = dry and not yellow.

FIGURE 11

Effects of 16 treatments on the YND leaves for 43 oat genotypes. See descriptions for each treatment in Table 1. YND leaves = yellow and not dry.