Saeed Ahmad Malik

Heat tolerance of upland cotton during the fruiting stage evaluated using cellular membrane thermostability

Excessively high temperature during the reproductive stage significantly reduces yield in cotton. The cellular membrane thermostability (CMT) assay indirectly measures integrity of cellular membranes through quantifying electrolyte leakage following heat treatment. Higher CMT has been related to heat tolerance and higher yields in several crop species, but its utility and relationship with seed cotton yield (SCY) is not well established. Experiments were carried out in the greenhouse and in the field under optimum and high temperature regimes, to assess the response of upland cotton to CMT. Upland cotton cultivars as well as hybrids differed significantly (P<0.01) for CMT. Although the temperature regimes modified the relative ranking of the cultivars and hybrids, heat-tolerant and susceptible groups remained quite stable. Cultivars FH-900, MNH-552, CRIS-19, and Karishma emerged as relatively heat-tolerant (thermostable) and FH-634, CIM-448, HR109-RT and CIM-443 as heat-susceptible. Exposure to high temperature prior to the CMT test produced better distinction between heat-tolerant and heat-susceptible cultivars and hybrids. The relationship between CMT and SCY was stronger among cultivars than among hybrids. The regression analysis indicated higher SCY due to higher CMT in the presence of heat stress. CMT was positively related to SCY under supra-optimum greenhouse conditions as well as early and late field regimes. Under optimum (non-stressed) greenhouse conditions, however, CMT was negatively related to SCY, indicating that susceptible cultivars and hybrids produced higher yields in the absence of heat stress. This also implied that in upland cotton these two traits were independent of each other, the presence or absence of heat stress determined their relationship. The differential ability of cotton cultivars and hybrids to adjust to CMT under heat-stressed conditions points towards physiological adaptation to heat stress or heat hardening in upland cotton. It was concluded that CMT could be a useful technique for differentiating heat-tolerant and susceptible cottons, however, its indirect selection on the basis of SCY under non-heat-stressed environments must be implemented with caution.

Drought impact on Pb/Cd toxicity remediated by biochar in Brassica campestris.

Heavy metals toxicity in the human being is creating an alarming condition in the world. Not only are these metals largely effecting the growth of many plants but also the consumer’s health. In sector of agriculture for many years Pakistan is facing the reduction in availability of edible oil. The demand is fulfilled by importation by spending huge cost. Brassica campestris L. is very important oil seed crop of Pakistan that is providing 31% of total oil seed production in Pakistan. But due to toxicity of metals like Cd and Pb its growth and yield is decreasing. Keeping in view the importance of Brassica campestris L. in Pakistan an experiment was conducted using Pollutary manure biochar as a reclaiming agent for heavy metals and an amendment as drought stress reducer to check the improvement in yield of Brassica campestris L. It is found that biochar application not only gave positive correlation in immobilization of Pb and Cd but also improves the plants growth and yield. Enhancements in the Photosynthetic and Accessory pigments are observed regarding good vegetative growth. Thus biochar can be utilized in reducing the metals uptake as well as growth promoter.

Biometric and biochemical attributes of alfalfa seedlings as indicators of stress induced by excessive cadmium

Abstract The biometric and biochemical attributes of alfalfa ( Medicago sativa L.) seedlings were studied after their exposure to 0-120 μM cadmium for 28 days using hydroponic culture. The growth, photosynthetic area and pigment contents (chlorophyll a, b and total) declined significantly ( p ≤ 0.05) in the presence of high cadmium concentrations (90 and 120 μM). A steady increase in lipid peroxidation assessed via MDA production was observed with increasing levels of cadmium. Cadmium uptake by the plant tissues was concentration dependent. The roots accumulated 1020 µg g-1 of cadmium which was two folds than leaves. An enhanced production up to 600 µg g -1 of proline was observed at higher levels of cadmium. Though, cadmium toxicity was expressed in terms of decline in growth variables, chlorophyll content and oxidative damage but restricted transfer of the metal to the aerial tissue and greater production of proline in response to higher metal content seems to alleviate cadmium toxicity. Thus, ability of alfalfa plants to tolerate high cadmium concentrations can be a manifestation of effective defensive mechanism derived from differential accumulation of metal in plant tissues in addition to enhanced production of proline.

Biochar affects growth and biochemical activities of fenugreek ( Trigonella corniculata ) in cadmium polluted soil

Cadmium (Cd) has no defined biological role and may enter the food chain from polluted soils. Biochar has been proposed as an organic amendment to minimize the toxic effects of Cd for plants grown on contaminated soils. In this study, biometric and biochemical attributes of fenugreek (Trigonella corniculata) grown on artificially cadmium (Cd) contaminated soil (0, 25, 50, 75 and 100 mg Cd/kg soil) at three levels of cotton-sticks derived biochar (CSB; 0, 3 and 5 %) were studied. Data show significant decline in the growth, photosynthetic pigments (chlorophyll a, b and total, carotenoids, anthocyanin and lycopene), and physiological attributes (sub-stomatal CO2 concentrations, photosynthetic and transpiration rate) in the presence of high Cd concentrations (50 and 100 mg Cd/kg soil). However, the decline was reduced in the presence of CSB. A steady amplification in lipid peroxidation (assessed via Malondialdihyde (MDA)) and ascorbic-acid assembly was noted with increasing Cd. The concentration of Cd in the root and shoot also decreased with increasing CSB application rates from 3 % - 5 %. Overall, the greater production of protein, amino acids and sugar contents in response to higher application rates of CSB seems to be due to alleviation in Cd toxicity. Thus, cotton-sticks can be safely utilized in the form of biochar as amendment with additional benefit of reducing Cd bioavailability and toxicity to crop plants.

Influence of urea application on growth, yield and mineral uptake in two corn (Zea mays L.) cultivars

A pot experiment was conducted in a wire netting green house in order to assess the beneficial effect of urea on corn cultivars (C-20 and C-79) differing in yield production. Corn plants were grown in loam soil with alkaline in reaction. Application of varying urea levels did not change the physico-chemical properties of soil. Four weeks-old corn plants were subjected to varying levels of urea (0, 50, 100, 175 and 225 kg/ha urea) for 8 (mid-season harvest) and 15 weeks (final harvest). After which, plants growth, yield and mineral nutrient status of the two corn cultivars were assessed for both mid-season and final harvest. It was observed that cv. C-20 showed higher (P<0.1) growth and yield. Addition of varying levels of urea enhanced the growth and yield of both the corn cultivars. However, 175 kg urea /ha was found to be more effective (P<0.1) in enhancing growth and yield of both the cultivars. The rate of urea application at a rate of 175 kg/ha had greater beneficial effect on cv. C-20 due to improved mineral nutrient (N, P, K, Cu, Fe, Mn and Zn) status of the cultivar. Keywords: Corn cultivars, fertilizer treatment, urea, mineral nutrition, plant growth