I= SALT TOLERANCE IN CANOLA WITH SPECIAL REFERENCE TO ITS REPRODUCTIVE PHYSIOLOGY UNDER SALINE CONDITIONS
Pakistan Research Repository Home
 

Title of Thesis
SALT TOLERANCE IN CANOLA WITH SPECIAL REFERENCE TO ITS REPRODUCTIVE PHYSIOLOGY UNDER SALINE CONDITIONS

Author(s)
Humaira Gul
Institute/University/Department Details
University of Karachi/ Department of Botany
Session
2003
Subject
Botany
Number of Pages
468
Keywords (Extracted from title, table of contents and abstract of thesis)
salt tolerance, canola, reproductive physiology, saline conditions, saline rhizosphere, germination, vegetative growth, reproductive growth, pollen viability, water requirement, growth period, biochemical changes, salinity, germination

Abstract
Investigations were undertaken to find out the effect of saline rhizosphere on germination, vegetative and reproductive growth, pollen viability, water requirement, growth period, biochemical changes and accumulation of minerals in different Canola varieties. Screening for the varieties capable of giving more yield under normal (non-saline) and saline environments were also performed. Following experiments were conducted for various objectives

1- Experiment No:1 (Germination Studies) Seeds of twelve different Canola varieties (Canola-I, Canola-II, Canola-III, Abasin-95, Westar, Ganyou-5, Ganyou-2, Oscar, Dunkled, Rainbow, Hyola-42, Shiralee) were germinated on sterilized filter paper in test tubes on Control (non-saline), 0.2, (EC 3.4 dS.m-1), 0.4 (EC 6.6 dS.m-1), 0.69(EC 9.8 dS.m-1), 0.8 (EC 10.6 dS.m-1), 1.0 (EC 14.2 dS.m-1), 1.2 (EC 16.8 dS.m-1) and 1.4% (EC 20.8 dS.m-1) NaCI solutions. Eight out of twelve varieties showed more thatn 80% germination in NaCI solutions up to 0.6% salinity level whereas, six varieties exhibited this performance up to 0.8% salinity level

In order to find whether germinated seeds were capable of forming seedlings at saline soil, five varieties (Canola-III, Oscar, Rainbow, Abasin-95 and westar) that gave better performance in above-mentioned experiments were germinated in plastic pots containing 1.5Kg saline soil. Salinity levels were achieved saturating the soil up to field capacity with the solutions formed by dissolving different percentages of sea salt in the water. Resulting Ece were: Control (non-saline), 0.2 (EC 3.8 dS.m-1), 0.4 (EC dS.m-1), 0.6 (EC 7.3 dS.m-1), 0.8 (EC 8.9 dS.m-1) and 1.0% (EC 3.8 dS.m-1), 0.4 (EC 5.6 dS.m-01), 0.6 (EC 7.3 dS.m-1), 0.8 (EC 8.9 dS.m-1) and 1.0% (EC 10.6 dS.m-1) respectively. Percentage of seedling formation in these five Canola varieties at saline soil were quite different from those seen for germination on filter paper. Greater reduction in seedling establishment was seen at higher soil salinity levels. Oscar and Rainbow showing 33 and 53% germination/establishment of seedlings under 0.6% sea salt salinity were found two best varieties in this respect

2. Experiment No:2 (Screening of different Canola varieties) Since susceptibility to salt varies at different stages of growth in plants, eight canola varieties (Dunkled, Canola-III, Oscar, Ganyou-5, Ganyou-2, Rainbow, Abasin-95 and Westar) were grown upto fowering and fruiting stages for screening purpose. They were raised in clay post each containing approximately 3Kg sandy soil, lined inside with plastic sheaths and having a basal outlet for drainage. In view of poor seedling establishment at higher concentration of salinity, the seedlings were grown with tap water up to five leaves stage prior to starting saline water irrigation. Plants were later irrigated with control (non-saline), 0.2% (EC 2.5 dS.m-1). 0.4% (EC 4.5 dS.m-1) and 0.6% (6.5 dS.m-1) sea salt dilutions permitting 10-15 leaching

There was some non-significant increase in vegetative parameters at lower salinity (0.2% sea salt dilution) but later the plant hight, number of leaves and branches and biomass exhibited proportional decrease with increasing salinity levels of irrigation medium. Grading of these varieties according to their shoot biomass was Oscar> Abasin-95> Dunkled>Canola-III>Rainbow>Ganyou-2=Westar>Ganyou-5 under non-saline and Oscar>Dunkled>Canola-III>Ganyou-5>Ganyou-2=Rainbow=Abasin-95>Wester under irrigation with 0.6% sea salt dilution

Delay by 15-20 days in flower initiation was most pronounced under saline conditions. With the exception of Canola var. Ganyou-2 which showed 11% increase only in plants undergoing irrigation of 0.2% sea salt dilutions. All the varieties exhibited decrease in flower formation proportionately to increase in salinity of irrigation medium. Grading of these varieties according to the total flower formed was Oscar > Rainbow > Dunkled > Canola-III > Westar > Ganyou-2 > Abasin-95 > Ganyou-5 > under non-saline and Oscar > Abasin-95 > canola-III > Dunkled > Rainbow > Ganyou-2 > Westar > Ganyou-5 under irrigation with 0.6% sea salt dilution. As far as yeld calculated in terms of seed weight per plant Canola varieties Oscar and Rainbow Occupy 1st two positions under non saline control as well as under saline water irrigation, through the production of seeds per plant was considerably reduced under saline condition. Var. Abasin-95 showing only 44% reduction in yield under irrigation with 0.6% sea salt dilution could also be considered a good candidate but its productivity in terms of total seeds per plant was less than that of above-mentioned two varieties

Viability percentages of pollen grain collected from different varieties of Canola undergoing irrigation with various sea salt dilutions determined vide tetrazolium salt staining were reduced proportionately with increase of salinity in irrigation water. Whereas Oscar, Ganyou-2 and Dunkled were found 1st three best varieties in this respect under control (non-saline) conditions. But when collected from the plants undergoing 0.6% sea salt irrigation, Ganyou-2 Rainbow and Oscar occupy 1st three positions. Germination percentage of pollen grains collected from Canola varieties undergoing irrigation of different sea salt dilutions was also reduced proportional to increasing salinity of irrigation water. Abasin-95, Rainbow and Canola-III=Westar were 1st 4 four best varieties in this respect under non-saline control whereas Dunkled, Canola-III=Abasin-95 and Oscar=Ganyou-5 occupy these positions when collected from plants undergoing 0.6% sea salt irrigation

Biochemical analysis exhibited decrease in chlorophyll contect and increase in sugar and protein level under saline water irrigation

Significant increase in the amount of Na+ in different plant parts, with increase in salinity of irrigation water was exhibited in all the varieties studied in different experiments, except in varieties Dunkled, Canola-III and Ganyou-2 which exhibited decrease of Na+ only at 0.2% sea salt level. The high level of Na+ accumulation found in plant parts of different varieties indicate that like other Crucifers, Canola species tend to be Na+ accumulators. The amount of K+ in different plant parts either showed reduction with increase in external salinity or exhibited non-significant differences

3. Experiment No:3 (Effect of different sowing dates on the vegetative and reproductive growth of Canola verities under different salinity levels) The Canola varieties (Oscar and Rainbow) were grown to find the suitable sowing date for maximum yield both under non-saline as well as saline conditions. Plants were grown in clay pots containing approximately 3 Kg soil each, lined inside with plastic sheaths having a basal outlet for drainage. Sowing was started on 15th September and continued up to 10th November at interval of every two weeks. Plants were irrigated with control (non-saline), 0.4% (EC 4.5 dS.m-1) and 0.6% (6.5 dS.m-1) sea salt dilutions. Var. Oscar and Rainbow sown at 27th October 2000 produced maximum fresh and dry shoot biomass under non-saline water irrigation but when subjected to saline water irrigation it exhibited reduction in fresh weight by 58 and 47% and dry weight by 57 and 49%. It appears that prevailing maximum temperature 36°C and minimum temperature 24°C with 46% R.H is most suitable for providing growth stimulus for biomass production

A good early vegetative growth carry plants earlier to reproductive phase and provides sufficient photosynthetic for developing fruits. There was non-significant difference between the reproductive yield of var. Oscar sown in the months of September and October whereas that of November was considerably reduced. The increase in sea salt in irrigation proportionately reduced the yield but the performance while comparing reduction with reference to seeds sown at some date and irrigated with non-saline water (control) remained same. The reproductive yield in var. Rainbow was better in plants sown towards end of September irrespective of saline concentration which followed reduction in plants sown at later dates

4. Experimental No:4 (Effects of different irrigation intervals on growth of Canola under different salinity levels) Investigations were carried to find out effect of irrigation intervals on growth of var. Oscar in lysimeters. A set of 48 plastic drums was installed at cemented platform in a slightly slanting position, having a basal outlet for draining the excess amount of water. They were filled with 300 Kg of coastal sand each, capable of retaining 45L of water at saturation. Var Oscar exhibited significant decrease in fresh and dry shoot biomass when irrigated at 6 days irrigation interval in both conditions

The pattern of comparative reproductive yield (in terms of seed weight per plant) between 2 and 4 days irrigation intervals in plant irrigated with non-saline water (control) and between those irrigated with water of different salinity levels wee almost same, whereas reproductive yield under 6 days irrigation interval was reduced considerably under both the above-mentioned intervals. Reduction in reproductive yield between non-saline (control) and saline water irrigation remained persistent under various irrigation intervals

5. Experiment No:5 (Effect of different fertilizers on the growth of Canola under saline water irrigation) Canola var. Oscar was grown in plastic buckets containing approximately 17 Kg soil each with leaching system to observe the effect of nitrogen, sulfur and phosphorus fertilizers under normal and saline water irrigation. Plants were irrigated with control (non-saline), 0.4% (EC 4.5 dS.m-1) and 0.6% (6.6 dS.m-1) sea salt dilutions supplemented with nitrogen @ 150 and 250 Kg/ha (through urea), sulfur @ 30 and 60 Kg/ha (though ammonium sulfate) and phosphorus @ 60 and 90 Kg/ha (through diammonium phosphate)

Supplementing nitrogen, sulfur and phosphorus fertilizers contributed an increase in shoot biomass irrespective of non-saline and saline conditions. Fresh shoot biomass of Canola var. Oscar control (non-saline irrigation water) without any fertilizer and salinity was 47.6 gm/pl. but when supplemented with 0.6% sea salt salinity it was reduced by 58.2% Fresh shoot biomass produced by amendment of nitrogen (250 Kg/ha) was 160.6 gms, amended by sulfur (60 Kg/ha) was 54.7 gms and amended by phosphorus (90 Hg/ha) was 99.8 gms per plant respectively. When irrigated with 0.6% sea salt dilution and amended with different fertilizers it was reduced by 53.5% in nitrogen, 41.0% in sulfur and 58.3% in phosphorus respectively in comparison with non-saline water supplemented with above-mentioned fertilizers. Hence it appears that inhibition effect on biomass production due to 0.6% sea salt salinity were offset by addition of nitrogen by 4.7% and sulfur by 17.2% while an amendment of phosphorus did not show any significant results

There was 300% increase in seed weight per plant under supplement of 250 Kg nitrogen per ha (through urea), non-significant changes under supplement of 60 Kg sulfur per ha (through ammonium sulfate) and 87.5% increase under supplement of 90 Kg phosphorus per ha (through diammonium phosphate) respectively under non-saline condition. While irrigation with 0.6% sea salt dilution without any fertilizer exhibited a reduction by 62.5%. Whereas supplement of above-mentioned fertilizers in 0.6% sea salt dilution showed 99.8% increase in case of nitrogen, 33.4% decrease in sulfur and non-significant changes in addition of phosphorus respectively. Amendment of lower doses of sulfur (30 Kg/ha) showed non-significant effect, but that of lower dose of phosphorus (60 Kg/ha) showed 33.2% increase at this parameter. Hence sulfur amendment dose not appear of any significance and has rather lower down seed production whereas lower dose of phosphorus increase productivity even under saline conditions

6. Experiment No:6 (Growth of Canola under different levels of saline soil) Investigation were also undertaken on Canola var. Ganyou-5 grown in china crock containing approximately 17Kg soil and without leaching system. Saline soil was made through supplementing various amount of sea salt in soil by dissolving in water that was just sufficient to bring it upto field capacity. Growth of this variety was observed in saline soil rather than saline water irrigation. Soil salinity were made as control (non-saline), 0.2 (EC 2.7 dS.m-1), 0.4 (EC 3.9 dS.m-1) and 0.6% (EC 5.7 dS.m-1) through sea salt amendment. It produced 16 gms fresh shoot biomass per plant and 8 gms dry shoot biomass per plant under non-saline control, while exhibited 35 and 18% reduction in fresh and dry shoot biomass under higher salinity level (EC 5.7 dS.m-1). Reproductive yield (seed weight per plant) under non-saline soil (control) was 2.18gms but exhibited 34.8% decrease in high salinity level (EC 5.7 dS.m-1). While comparing seed weight per plant in Ganyou-5 (experiment No 2 and 6) it might be noted that reduction in seed formation per plant at soil (without leaching practice) EC 5.7 dS.m-1 was 34.8% whereas with irrigation water of same salinity (with leaching practice) was 86.3% which shows that considerable amount of minerals that were essential for plant growth have been leached out from rhizosphere

7. Experiment No:7 (Effect of saline water irrigation on the growth of Canola under field conditions) Canola var. Oscar was grown on non-saline sandy loam irrigated with 0.6% (EC 6.5 dS.m-1) sea salt dilution under field conditions. This variety produced 67gms fresh shoot biomass and 25gms dry shoot biomass per plant under non-saline control, while exhibited 16 and 20% reduction in fresh and dry shoot biomass respectively, under saline water irrigation. Reproductive yield (seed weight per plant) when irrigated with non-saline water (control) was 11.2 gm/pl. and showed 45.5% reduction when irrigated with 0.6% sea salt dilution under field conditions

Download Full Thesis
4671.7 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents 0
234.31 KB
2 1 Introduction 1
285.39 KB
  1.1 Salinity Problem 2
  1.2 Causes Of Primary Salinity 3
  1.3 Secondary Salinization 3
  1.4 Salt Affected Soils 4
  1.5 Use Of Saline Water For Irrigation 5
  1.6 Salinity Extent In The World 6
  1.7 Salinity Problem In Pakistan 6
  1.8 Minimizing The Effect Of Salinity 7
  1.9 Salinity And Agriculture 9
  1.10 Physiological Response 10
  1.11 Mechanism Of Salt Tolerance 17
  1.12 Plant Factors Affecting Salt Tolerance 18
  1.13 Enhancing Salt Resistance In Crop Plants 19
  1.14 Reproductive Yield Under Salinity 22
  1.15 Salt Tolerant Plants Of Commercial Utilization 23
3 2 Materials And Methods 29
139.83 KB
  2.1 Experiment No:1 (Germination Studies) 29
  2.2 Experiment No:2 (Screening Of Different Canola Varieties) 30
  2.3 Experiment No:3 (Effect Of Different Sowing Dates On The Vegetative And Reproductive Growth Of Canola Verities Under Different Salinity Levels) 33
  2.4 Experimental No:4 (Effects Of Different Irrigation Intervals On Growth Of Canola Under Different Salinity Levels) 3 4
  2.5 Experiment No:5 (Effect Of Different Fertilizers On The Growth Of Canola Under Saline Water Irrigation) 36
  2.6 Experiment No:6 (Growth Of Canola Under Different Levels Of Saline Soil) 36
  2.7 Experiment No:7 (Effect Of Saline Water Irrigation On The Growth Of Canola Under Field Conditions) 38
  2.8 Analytical Procedures 39
  2.9 Pollen Vaiability 43
4 3 Observations And Results 45
3861.45 KB
  3.1 Experiment No:1 (Germination Studies) 45
  3.2 Experiment No:2 (Screening Of Different Canola Varieties) 45
  3.3 Experiment No:3 (Effect Of Different Sowing Dates On The Vegetative And Reproductive Growth Of Canola Verities Under Different Salinity Levels) 177
  3.4 Experimental No:4 (Effects Of Different Irrigation Intervals On Growth Of Canola Under Different Salinity Levels) 251
  3.5 Experiment No:5 (Effect Of Different Fertilizers On The Growth Of Canola Under Saline Water Irrigation) 290
  3.6 Experiment No:6 (Growth Of Canola Under Different Levels Of Saline Soil) 356
  3.7 Experiment No:7 (Effect Of Saline Water Irrigation On The Growth Of Canola Under Field Conditions) 380
5 4 Discussion 400
269.42 KB
  4.1 Germination 400
  4.2 Vegetative Growth 401
  4.3 Reproductive Growth 409
  4.4 Biochemical Analysis 417
  4.5 Mineral Analysis 418
  4.6 Changes In Soil Characteristics 420
  4.7 Conclusion 421
6 5 References 422
421.48 KB