The Response of Fodderbeet to Salinity : Introduction of a non-conventional fodder crop (Fodderbeet) to salt affected lands of Pakistan

Summary In the experiments described in this thesis on fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral and seabeet Beta vulgaris subsp. maritima grown under saline conditions the seed germination of four fodderbeet Beta vulgaris subsp. vulgaris cultivars was first studied in response to salinity (EC 4-20 dS m-1~ 40-200 mM NaCl) and three temperatures (20o, 25o and 30 oC). The germination rate of seeds of fodderbeet Beta vulgaris subsp. vulgaris cultivars at 25 oC was somewhat higher than at 20o and 30 oC. Overall the germination of the fodderbeet seeds decreased with increasing salinity. The germination rate of fodderbeet Beta vulgaris subsp. vulgaris cv. Monoval compared to the Beta vulgaris subsp. vulgaris cvs. Majoral, Monored and Polygroeningia was somewhat higher at increasing salinity levels (chapter 2). Yet at the average salinity (EC 5-15 dS m-1) of saline arable soil in Pakistan, the germination rate was about 70 %. In growth experiments with increasing salinity (chapter 3 and 4), fodderbeet cultivars were screened for salt tolerance. Fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral showed to be a relatively salt tolerant cultivar. Growth and physiology of fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral was compared with that of its primary ancestor seabeet (Beta vulgaris subsp. maritima). Physiological and morphological aspects of growth were studied first in response to salinity in nutrient solution (chapter 3). Both fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral and seabeet Beta vulgaris subsp. maritima tolerated a salinity level of 200 mM NaCl. Among the four fodderbeet cultivars tested, Beta vulgaris subsp. vulgaris cv. Majoral was found to be a promising non-conventional fodder crop plant for cultivation in saline arable land in Pakistan. Further investigations into the growth and physiology of fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral and seabeet Beta vulgaris subsp. maritima plants were conducted in relation to ion uptake and to the concentrations of osmolytes (sugars, proteins, proline and glycinebetaine) in the shoot tissue under saline conditions (chapter 4). The levels of the osmolytes glycinebetaine and proline in fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral and seabeet Beta vulgaris subsp. maritima increased at intermediate salinity levels. The concentrations of proline and glycinebetaine in fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral tissue are discussed in relation to tolerance to saline conditions (chapter 4). Another experiment was conducted to explore the growth response of the four cultivars of fodderbeet under saline-sodic field conditions in Pakistan (chapter 5). The plant biomass (beets and leaves) of fodderbeet Beta vulgaris subsp. vulgaris cultivars Majoral and Monored increased grown under saline-sodic soil conditions compared to non-saline soil conditions. The pH and EC of saline soil decreased (pH 8.15 ? 7.56 at 0-15 cm and 8.26 ? 8.03 at 15-30 cm soil depth and ECe 11.38 ? 7.39 dS m-1 at 0- 15 cm and 6.72? 5.61 dS m-1 at 15-30 cm respectively) after harvesting of fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral crop compared to pre-sowing values. The leaf chlorophyll ‘a’ and chlorophyll ‘b’ conctentrations increased with increasing soil salinity. The sugar concentrations of the beets of all four fodderbeet cultivars increased with increasing NaCl, while that of the leaves decreased in Beta vulgaris subsp. vulgaris cvs. Majoral and Monoval. The leaf proline concentrations however, increased under saline conditions in all the cultivars tested indicating fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral to be a salt tolerant plant. A comparison was made between fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral biomass production with that of two conventional crops barley and oat, cultivated under field conditions in a saline-sodic soils in Pakistan. Biomass production of fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral was significantly higher than that of barley and oat. The fodderbeet had a larger number of leaves per plant with a nearly double leaf area per plant compared to barley and oat. Fodderbeet had a three times higher average fresh weight of the whole plant. FYM is used as a source of nutrients to plants when added to the arable fields. The FYM is used by the farmers to increase the soil fertility status to enhance crop production. Addition of FYM highlighted the economical utilization of otherwise unproductive salt-affected soils in Pakistan by growing fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral plants. The mixing of FYM with non-saline soils significantly improved the fertility of the soil. The mixing of FYM to the saline-sodic soils however, depressed the growth of fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral plant compared to that grown in soil without addition of FYM (Chapter 5, Table 12). The increased concentrations of glycinebetaine, sugars and proline of the above-ground parts of fodderbeet may relate to its tolerance of saline-sodic conditions. However, the salt tolerance of fodderbeet in saline-sodic soil was not increased after addition of FYM. The fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral fed to the cattle at NARC, Islamabad, Pakistan was found palatable, when the leaves and beets were chopped and mixed with the conventional fodder (barley). There was no disorder in the digestion of the cows during the 15 days feeding of fodderbeet. The results of these experiments are discussed in chapter 5. The experiments conducted in the laboratory, greenhouse and field (chapter 2, 3, 4, and 5) have revealed that the fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral can tolerate a salinity of 200 mM NaCl in the root medium. The production of biomass (leaves and beets) of fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral was shown to be comparatively higher than that of two conventional fodder crops, barley and oat grown in Pakistan. The day temperature during the winter season in Pakistan ranges from 20o to 30 oC, which is suitable for the germination of fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral seeds based on the results of the germination experiment described in chapter 2. Therefore, it may be expected that fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral could be economically cultivated on saline arable land in Pakistan as a fodder crop in addition to the conventional crops, barley (Hordeum vulgare) and oat (Avena fatua). The cropping season of fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral in Pakistan (mid October to mid April) also coincides with the period when there is a shortage of conventional fodder for cattle. Introduction of the fodderbeet Beta vulgaris subsp. vulgaris cv. Majoral will help in the utilization of non-productive saline-sodic soils by production of a fodder crop during this period of shortage of fodder for cattle.