Planting Materials
The seeds of four maize varieties namely cv. Kaveri-244+, cv. BHARAT Hybrid Sultan 702, cv. Getco seeds GP–901, cv. Essence–Platinum were collected from Bangladesh Agriculture Research Institute (BARI) and used as experimental materials.
Experimental Laboratory The Experiment was conducted at Crop Physiology Laboratory, Department of Crop Botany, Bangladesh Agricultural University, Mymensingh, Bangladesh during the period from December, 2015 to July, 2016.
Pot Preparation
The black colored pots were taken with Hogland's full strength nutrient solutions and an aeration pump was attached to supply oxygen into the water. After this, the experimental pots were laid out as per treatments and design.
Experimental Design
The experiment was laid out in Completely Randomized Design (CRD) with three replications having two treatments comprising NaCl application. The individual pot size was 8L. Each treatment received equal amount of macro and micro nutrients. Total number of water tank used in this study were (4×3×2) = 24. The treatments were randomly distributed to the tank. All the experiments were conducted in a growth room at 25°C under a 12 hour-light and 12 hour-dark regimes, 70% relative humidity and pH adjusted at 6.5.
Application of NaCl and Nutrients
During germination stage, NaCl solution of 8 dSm-1 concentration was sprayed to the seeds on Petri dishes for T2 and distilled water was sprayed to the seeds on Petri dishes of control treatments to ensure 0 dS m-1 . All other nutrients except NaCl were incorporated to the tank at recommended dose. Eight (8) dS m-1 NaCl solutions were added to the water into the tank at an eight days interval.
Hydroponic Experimental Set-Up
One-week-old seedlings were transferred to continuously aerated nutrient solution in 8L plastic tank on Styrofoam blocks with 4 holes and three plants per hole, supported with a sponge. The solution was renewed with fresh nutrient solutions in 8 days interval. The composition of the nutrient solution was presented below:
Data Collection
Data on the following parameters at the transfer day of seedling to plastic tank on Styrofoam blocks (0 Das) and 14 days after transfer (14 DAS) were recorded. The following morphological characteristics at selected stages of seedlings were collected: (a) Root length (b) Shoot length (c) No. of leaves/plant (d) Fresh weight of root and shoot (e) Dry weight of root and shoot. After collection of data of maize seedlings, 0 and 14 DAS maize seedling's root and shoot of selected varieties was collected and dried. The seedlings were collected and prepared to study the fresh and dry weight. The weights of 4 fresh seedlings were recorded and the seedlings were placed in an oven for 24 hrs at 80±2°C. Then the dry weights were measured using an electrical balance.
Statistical Analysis
Data were statistically analyzed for analyses of variance (ANOVA) using the M-STAT Statistical Computer Package Programme in accordance with the principles of Completely Randomized Design (CRD). Duncan’s Multiple Range Test (DMRT) was used to compare variations among the treatments.