Electrical conductivity could have a role in predicting germination and vigour in Brassica spp. Zohair Mirdad and Alison A Powell King Abdul Aziz University, Jeddah, Saudi Arabia University of Aberdeen, Aberdeen, UK
Background Conductivity and germination: Single seeds: problems Bulk samples: Mirdad and Powell (26); SST EC predicts germination in artificially aged cauliflower and cabbage Demir et al (28); SST 16 commercial cabbage seed lots (2 cvs): EC predicts both standard germination and germination after CD (vigour) Matthews, Demir, Celikkol, Kenanoglu and Mavi (29) SST 12 commercial cabbage lots (1 cv): EC before and after CD estimate emergence in modules
Objectives 1. Examine evidence from storage studies for a relationship between germination and EC within and across cultivars 2. Could EC replace the germination test that follows controlled deterioration (CD)? 3. Does EC after CD predict storage potential (vigour)?
Methods 4 commercial lots (cultivars) of cauliflower Storage:12% MC, 25 o C, 12 weeks Regular sampling Germination, CD and EC tests EC both before and after CD (CD/EC) 4 x 1 weighed seeds, 4 ml deionised water, 2 o C, 24h
Normal germination (%) EC (µs cm -1 g -1 ) Normal germination (%) EC (µs cm -1 g -1 ) Normal germination (%) EC (µs cm -1 g -1 ) Normal germination (%) EC (µs cm -1 g -1 ) 1 8 A1 45 36 1 8 A3 45 36 6 27 6 27 4 18 4 18 2 9 2 9 2 4 6 8 1 12 Storage time (weeks) A3 A4 A4 2 4 6 8 1 12 Storage time (weeks) 1 8 A4 45 36 1 8 EL 45 36 6 27 6 27 4 18 4 18 2 9 2 9 2 4 6 8 1 12 2 4 6 8 1 12 Storage time (weeks) Storage time (weeks) Increased conductivity linked to reduced germination
Normal germination (%) Normal germination (%) Normal germination (%) Normal germination (%) 1 A1 1 A3 8 6 4 r =.92 R 2 =.85 p<.1 8 6 4 r =.95 R 2 =.9 p<.1 2 2 1 2 3 4 5 1 2 3 4 5 EC (µs cm -1 g -1 ) EC (µs cm -1 g -1 ) 1 A4 1 EL 8 r =.99 8 r =.96 6 R 2 =.98 p<.1 6 R 2 =.92 p<.1 4 4 2 2 1 2 3 4 5 1 2 3 4 5 EC (µs cm -1 g -1 ) EC (µs cm -1 g -1 ) Conductivity predicts normal germination within a cultivar Cultivar differences?
Normal germination (%) 1 A1 8 6 EL A4 r =.88 R 2 =.77 P<.1 4 2 2 4 6 A3 EC (µs cm -1 g -1 )
Survival curve Small increases in EC (A1, EL) Large increases in EC (A4, A3)
What can we conclude so far? EC predicts germination within a cultivar Differences in leakage (EC) between cultivars relate to position on survival curve. i.e. seed quality has determined the cultivar differences But do seed lots from different cultivars having the same seed quality differ in leakage? The key question for use of EC in evaluating seed quality
2 nd objective 1. Examine evidence from storage studies for a relationship between germination and EC within and across cultivars 2. Could EC replace the germination test that follows controlled deterioration? 3. Does EC after CD predict storage potential (vigour)?
CD germination (%) CD/EC (µs cm -1 g -1 ) CD germination (%) CD/EC (µs cm -1 g -1 ) CD germination (%) CD/EC (µs cm -1 g -1 ) CD germination (%) CD/EC (µs cm -1 g -1 ) 1 8 6 A1 7 6 5 4 1 8 6 A3 7 6 5 4 4 2 3 2 1 4 2 3 2 1 2 4 6 8 1 12 2 4 6 8 1 12 Storage time (weeks) Storage time (weeks) 1 8 6 4 2 A4 7 6 5 4 3 2 1 2 4 6 8 1 12 Storage time (weeks) 1 8 6 4 2 EL 2 4 6 8 1 12 Storage time (weeks) 7 6 5 4 3 2 1 Increased conductivity linked to a fall in CD germination
CD germination (%) CD germination (%) CD germination (%) CD germination (%) 1 8 A1 1 8 A3 6 6 4 2 r =.97 R 2 =.94 p<.1 4 2 r =.96 R 2 =.92 p<.1 1 2 3 4 5 6 7 1 2 3 4 5 6 7 CD/EC (µs cm -1 g -1 ) CD/EC (µs cm -1 g -1 ) 1 A4 1 EL 8 8 6 6 4 2 r =.99 R 2 =.98 p<.1 4 2 r =.9 R 2 =.81 p<.1 1 2 3 4 5 6 7 1 2 3 4 5 6 7 CD/EC (µs cm -1 g -1 ) CD/EC (µs cm -1 g -1 ) CD /EC predicts CD germination
CD germination (%) 1 EL A1 8 6 4 A4 r =.96 R 2 =.92 p<.1 2-1 1 3 5 7 CD/EC (µs cm -1 g -1 ) A3
3 rd objective 1. Examine evidence from storage studies for a relationship between germination and EC within and across cultivars 2. Could EC replace the germination test that follows controlled deterioration? 3. Does EC after CD predict storage potential (vigour)?
Correlations with normal germination after storage: 4 seed lots of cauliflower Pre-storage assessment 1 weeks storage 12 weeks storage EC -.568 -.737 CD germination.995 **.975 * CD/EC -.95 * -.986 **
Normal germination (%) Normal germination (%) Normal germination (%) Normal germination (%) 1 1 8 8 6 r =.18 6 r =.97 4 2 R 2 =.3 NS 4 2 R 2 =.94 P<.1 2 4 6 8 1 2 4 6 8 1 Pre-storage normal germination (%) Pre-storage CD germination (%) 1 1 8 8 6 6 4 2 r =.74 R 2 =.55 NS 5 7 9 11 13 15 4 2 r =.98 R 2 =.95 p<.1 1 15 2 25 3 35 Pre-storage EC (µs cm -1 g -1 ) Pre-storage CD/EC (µs cm -1 g -1 ) CD/EC predicts storage potential
Concluding comments 1. EC relates to germination within cultivars Seed quality determines level of leakage (EC) Further studies to compare cultivars same seed quality 2. CD/EC predicts CD germination Possibility to reduce time for CD test? 3. CD/EC predicts storage potential
Electrical conductivity does have a role in predicting germination and vigour in Brassica spp.