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Influence of Potassium on Stomatal Response and Gas Exchange Characteristics of Triticum Aestivum L. Under Different Soil Moisture Regimes

M. A. Baque
Dept. of Agronomy, Sher-e-Bangla Agricultural University, Sher- e-Bangla Nagar, Dhaka, Bangladesh

Abstract/ Executive Summary:

Wheat variety Satabdi (BARI Gam 21) was grown in K deficit soil in pots inside vinyl house under natural light. Three levels of each of potassium (39.0, 156.42 and 312.85 kg ha') and soil moisture viz. control (less than 25% depletion from field capacity FC), mild stress (more than 37.5% depletion from FC) and severe water stress (more than 50% depletion From FC) were the treatment variables. Higher doses of potassium in wheat generally showed the higher stomatal density, stomatal length and breadth, faster transpiration rate and significantly reduced diffusive resistance at all the soil moisture regimes. However, the beneficial effect of potassium on stomatal response and gas exchange in wheat plants were more pronounced under water stressed conditions than that under control conditions.

Keywords: Stomatal response. Gas exchange, Water stress, Potassium, Wheat

Location: Environmental Stress Research Site of Agronomy Division at the Bangabandhu Sheikh Mujibur Rahman Agricultural University, Salna, Gazipur

Start Date: 00-11-2001

End Date: 00-03-2002

Program Area: Crop-Soil-Water Management

Commodity: Fertilizer, Wheat

Objectives:

To analyze the role of potassium on stomatal response and gas exchange characteristics of wheat subjected to water stress.

Methodology:

A pot experiment was conducted under semi- controlled environmental (inside vinyl house) conditions at the Environmental Stress Research Site of Agronomy Division at the Bangabandhu Sheikh Mujibur Rahman Agricultural University, Salna, Gazipur during winter (November 2001- March 2002). The experimental soil was K deficit, sandy-loam in texture and slightly acidic in nature (pH = 5.6) with poor fertility status (Total nitrogen = 0.064%; available P = 27 ppm and exchangeable K = 0.05 meq/l00 g dry soil). Three levels of each of potassium (39.0, 156.42 and 312.85 kg/ha) and soil moisture viz. control (less than 25% depletion from field capacity FC), mild stress (more than 37.5% depletion from FC) and severe water stress (more than 50% depletion from FC) were the treatment variables. A randomized block design with four replications was used. Plastic pot of 24 x 30 cm was filled-up with 14.05 kg air-dried soil (contained 12% moisture) and kept inside plastic greenhouse under natural light. Required amount of water was added to the pot to maintain the respective moisture levels. Soil moisture levels were maintained throughout the growing season by weighing everyday, randomly selected 50% pot per treatment. Diffusive resistance (dr.) and Transpiration rate (Tr.) were measured at anthesis with Steady State Porometer (Model L1-1600) at 11.00-13.00 hr. The measurement was made using the fully developed flag leaf. Stomatal density and stomatal length and breadth were measured at anthesis stage with the help of a special type of Japanese glue, cover slip and stereo microscope containing oculometer. At first, 1-2 drops of glue was placed on the cover slip. Then the cover slip was adjusted with the flag leaf at I 1.00 am by gentle pressing. After half an hour the cover slip remove carefully and taken to the lab for estimating stomatal density (number/mm^-2), and stomatal length and breadth (µm). The original size of the stomata was calculated by using a standard formula. The data recorded on different parameters were statistically analyzed with the help of "MSTAT" program. The differences between the treatment means were compared by Least Significant Difference (LSD) test at 5% level of significance after performing ANOVA.

Source of Information: Progress. Agric. 14(1 & 2) : 53-56, 2003, ISSN 1017-8139

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Increases of potassium level reduced guard cell ABA level by maintaining cell turgor, ultimately stomata opened. resulting in reduced leaf diffusive resistance and increased transpiration rate under low soil moisture condition. With the increases of active uptake of potassium ion into guard cells, the stomata might be opened due to increase in cell turgor.

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