Effects of Lead on Different Seedling Growth Attributes of Cowpea (Vigna unguiculata L.)| Chapter 04 | New Perspectives in Agriculture and Crop Science Vol. 1
Aims:
This study was conducted to determine the toxicity and tolerance to lead by the
seedling growth of an important country legume crop cowpea (Vigna unguiculata
L).
Study Design: The seedlings of cowpea
were grown in sand culture at 0, 20, 40, 60, 80 and 100 ppm of metal ions of
lead salt as lead acetate.
Place
and Duration of Study: The experimental site is located in
the Department of Botany at the Karachi University Campus, Pakistan in 2011.
Methodology:
The healthy seeds of Vigna unguiculata L. were surface sterilized with 0.2%
solution of sodium hypochlorite (NaOCL) for one minute to avoid any fungal
contamination. The sand was collected from the construction site of the Karachi
University washed 2-3 times with tap water, distilled water and with 5% HCl to
remove any types of impurities from the soil. Seedlings were grown in sand
culture at 0, 20, 40, 60, 80 and 100 ppm of metal ions of lead salt as lead
acetate. The Hoagland solution was used for the supply of nutrient elements.
The experiment was conducted for six weeks. 5 ml of lead concentration were
poured weekly and before given concentration of lead, the materials of the tray
were drained out to avoid any algal contaminations. The experiment was
completely randomized and consists of six treatments replicated six times.
After six weeks, the seedlings were harvested and morphological parameters
shoot, root, seedling length (cm), number of leaves and leaf area (sq. cm) was
noted. The biomass production such as shoot, root, leaf and total seedling dry
weight (g) was also observed along with root/shoot, leaf weight, leaf area
ratio and specific leaf area. The seedlings of cowpea were dried in an oven at
80°C for 24 hours until the seedlings were completely oven dried. Leaf area,
Root/shoot ratio, leaf weight ratio, specific leaf area, leaf area ratio was
determined, and a tolerance index was determined. The data obtained were
statistically analyzed.
Results:
The effects of different concentrations (0, 20, 40, 60, 80, 100 ppm) of lead on
seedling growth performance of cowpea (Vigna unguiculata L.) as compared to
control were observed. 100 ppm lead treatment in the form of lead acetate
highly affected seedling growth and biomass production of V. unguiculata L. as
compared to control Lead treatment at 40 ppm produce significant (P = .05). %
reduction in seed germination of V.
unguiculata L. as compared to control. Lead treatment at 20 ppm concentration
produced a significant reduction in shoot length as compared to control. Root
growth is an important growth variable and found negatively affected by the
different concentration of lead treatment. The results also showed that lead
treatment in the substrate at the same concentration (20 ppm) produced a
significant effect on root and seedling growth of V. unguiculata L. The
treatment of lead at 20 ppm produced significant (p<0.05) on the seedling
dry weight of V. unguiculata L. as compared to control. 80 ppm concentration of
lead treatment was found sufficient to cause significant % reductions in the
seedling dry weight of V. unguiculata L. as compared with control. The
seedlings of V. unguiculata L. were also tested for percentage of tolerance to
lead. The results showed that V. unguiculata L. has a high tolerance to lead at
20 ppm and lowest at 80 ppm of lead. V. unguiculata seedlings showed the
highest percentage of tolerance (92.50%) to lead at 20 ppm. The lowest V.
unguiculata seedlings were 64.50% at 80 ppm of lead, but better tolerance of V.
unguiculata L. seedlings was 73.25% at 60 ppm of lead concentration.
Conclusion:
In conclusion, lead was toxic causing significant reduction (P = .05). to the
seedling and biomass production of cowpea. Increased in lead concentration
decreased the tolerance indices of cowpea seedlings growth.
Author(s) Details
Sahar
Mehboob
Department
of Botany, University of Karachi, Karachi-75270, Pakistan.
M.
Zafar Iqbal
Department
of Botany, University of Karachi, Karachi-75270, Pakistan.
Muhammad
Shafiq
Department
of Botany, University of Karachi, Karachi-75270, Pakistan.
Muhammad
Kabir
Department
of Biological Sciences, University of Sargodha, Sub Campus Bhakkar, Pakistan.
Zia-ur-Rehman
Farooqi
Department
of Botany, University of Karachi, Karachi-75270, Pakistan.
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