M Monjurul Alam Mondal
Crop Physiology Division, Bangladesh Institute of Nuclear Agriculture, Mymensingh, Bangladesh
Md Solaiman Ali Fakir
Department of Crop Botany, Bangladesh Agricultural University, Mymensingh, Bangladesh
Mohd Razi Ismail
Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
M Ashrafuzzaman
Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
Canopy structure; Defoliation; Dry matter production; Mungbean; Seed yield
Field Laboratory of Bangladesh Agricultural University (BAU), Mymensingh
Crop-Soil-Water Management
Site description - Experiments were conducted at the Field Laboratory of Bangladesh Agricultural University (BAU), Mymensingh (2408´ N 9000´ E), Bangladesh in Kharif-I (February-May) season, 2008 and 2009. The soil of the experimental area of Crop Botany field laboratory, BAU is silty loam having a total nitrogen 0.06%, organic matter 1.15%, available phosphorus 18.5 ppm, exchangeable potassium 0.28 meq/100g, sulphur 18 ppm and pH 6.8. Planting materials and experimental design Two high yielding (BMX 942-8 and VC 6173) and two low yielding (MB 300 and VC 3960) genotypes were used. Seeds were sown in rows, 4 m long and 30 cm apart. Planting was done on 22 and 18 February for the year 2008 and 2009, respectively. The experimental design was split-split-plot with three replications i.e. the season was assigned in the main plot and four genotypes were in the sub-plot and eight defoliations were in the sub-sub-plot. The sub-plot consisted of 18 rows including two borderlines on either side. The subsub- plot consisted of two rows at 30 cm apart and each 4.0 m in length. Management practices - Seeds were sown continuously in line and two weeks after germination, the plants were thinned to a density of 30 plants/m2. Cultural practices were the same in both the seasons and locations. Uniform plant stands (30 plants/ m2) were maintained in both the seasons. Urea, triple superphosphate, muriate of potash and gypsum were used as a source of nitrogen, phosphorus, potassium and sulphur at the rate of 40, 120, 80 and 30 kg ha-1, respectively at the time of final land preparation. First weeding was done followed by thinning at about 21 days after sowing (DAS). A single irrigation was given at 25 DAS at both the seasons. Insecticide (Ripcord 50 EC at 0.025%) was sprayed at flowering and fruiting stage (55 DAS) to control shoot and fruit borer. Treatments - The eight levels of defoliation treatments were employed at the beginning of opening of flowering stage (40 and 35 days after sowing in 2008 and 2009, respectively) were: i) control (no leaf removal), ii) 25 % leaves removed from bottom (basal 25%), iii) 25 % leaves removed from top (top 25%), iv) similarly bottom 50%, v) top 50%, vi) bottom 75%, vii) top 75% and viii) 100 % leaves removed. Total leaf area (LA) plant-1 from ten randomly selected plants of each subsub- plot was determined by measuring leaf area at individual node in the mainstem using automatic leaf area meter (Model: LI 2000). Considering total LA plant-1 as hundred per cent, contribution of LA at each nodal position in the mainstem was estimated. Leaf in the branches, initiated in a particular node was included in that nodal position of the mainstem. Contribution of individual nodal LA to total LA plant-1 was estimated. To defoliate leaf at different degrees, complete compound leaf and/ or leaves, and sometimes one or two leaflets or even a portion of a leaflet were clipped off. Parameters measured - A 3.0 m central section of each row was harvested to avoid border effects. The harvested plants of each sub-sub-sub plot was separately bundled and tagged. After recording some desired data, the harvested bundles were hand threshed and oven dried weights of plants parts (800C ± 2 for 48 hours) were recorded plot-wise. Daily flower count began from the date of opening of first flower of the randomly selected 15 plants, 5 from each replication and continued until flowering ceased in each treatment. Finally, at harvest leaf area, seed yield and yield components, dry matter production and it’s partitioning into plant parts were recorded. Per cent podset to opened flower, leaf area index (LAI), total dry matter (TDM) and harvest index (HI) were calculated. The TDM plant-1 was estimated by summing dry matter of root, stem, leaves and pods dry weight per plant. Harvest index was determined as: (Grain yield plot-1 ÷ biological yield plot-1) × 100. Per cent pod set to opened flowers was calculated as follows: % pod set = (Number of pods plant-1 ÷ Number of opened flowers plant-1) × 100. Statistical analysis - All data were analyzed statistically as per the used design following the analysis of variance (ANOVA) technique and the mean differences were adjusted with Duncan’s Multiple Range Test (DMRT) using the statistical computer package program, MSTAT-C (Russell, 1986). Microsoft Excel was used for graphical presentation.
AJCS 5(8):987-992 (2011); ISSN:1835-2707
Journal