Growth parameters such as leaf area (LA), total dry mass (TDM) production, crop growth rate (CGR), relative growth rate (RGR), and net assimilation rate (NAR) were compared in six varieties of mungbean under subtropical condition (24°8′ N 90°0′ E) to identify limiting growth characters for the efficient application of physiology breeding for higher yields. Results revealed that a relatively smaller portion of TDM was produced before flower initiation and the bulk of it after anthesis. The maximum CGR was observed during pod filling stage in all the varieties due to maximum leaf area (LA) development at this stage. Two plant characters such as LA and CGR contributed to the higher TDM production. Results indicated that high yielding mungbean varieties should possess larger LA, higher TDM production ability, superior CGR at all growth stages, and high relative growth rate and net assimilation rate at vegetative stage which would result in superior yield components.
Mungbean is one of the most important pulse crops for protein supplement in subtropical zones of the world. It is widely grown in Indian subcontinent as a short duration catch crop between two principal crops. Mungbean contains 51% carbohydrate, 24–26% protein, 4% mineral, and 3% vitamins [
In spite of the best efforts for improving the mungbean varieties, the yield of this crop remains low. Several studies have been made to understand their performances which mainly include the contribution of various yield components towards yield [
The experiments were carried out at the experimental field of Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh (24°8′ N 90°0′ E), Bangladesh in Kharif-I (February-May) season of 2010 and 2011. Six mungbean varieties of which three high (BARImung-4, BINAmung-7, and BUmung-1) and three low (BARImung-6, BINAmung-6, and BUmung-2) yielding varieties were used as planting material. The soil of the experimental area is silty loam having a total of 0.065% nitrogen, 1.17% organic matter, 18.5 ppm available phosphorus, 0.30 meq/100g exchangeable potassium, 20 ppm sulphur and 6.8 pH. The experiments were laid out in a randomized complete block design with three replicates in both the years. 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. Seeds were sown on 10 and 14 March for the year of 2010 and 2011, respectively. A unit plot size of 20 m2 (
To study ontogenetic growth characteristics, a total of five harvests were taken in both years. The second and third rows of each plot were used for sampling. The first crop sampling was done at 25 DAS, and continued at an interval of ten days up to 65 DAS, that is, till attaining physiological maturity. From each sampling, a unit area of 0.3 m2 in two adjacent rows of 0.5 m (10 plants) was randomly selected from each plot and uprooted for collecting necessary parameters. The plants were separated into roots, stems, leaves, and pods, and the corresponding dry weight was recorded after oven-drying at
Data were analyzed statistically as per the design used following the analysis of variance (ANOVA) technique and the mean differences were adjusted with DMRT at 5% level of significance using the statistical computer package programme, MSTAT-C following Russell [
The differences among the varieties for leaf area (LA) and total dry mass (TDM) were significantly different at all growth stages (Figures
Variation in morphological, reproductive, and phenological parameters in six mungbean varieties (mean over two years).
Variety | Plant height (cm) | Branches plant−1 (no.) | Flowering duration (days) | Total opened flowers plant−1 (no.) | Reproductive efficiency (%) | Days to maturity |
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BARImung-4 | 60.3 a | 2.77 a | 32.5 a | 80.3 a | 44.9 c | 74.7 a |
BARImung-6 | 38.2 c | 0.69 c | 10.3 c | 19.2 d | 80.0 a | 60.0 d |
BINAmung-6 | 40.3 c | 0.72 c | 10.2 c | 19.0 d | 79.3 a | 60.9 d |
BINAmung-7 | 56.6 b | 2.66 a | 33.5 a | 72.7 b | 56.0 b | 73.7 a |
BUmung-1 | 58.1 ab | 2.29 b | 25.2 b | 55.2 c | 57.2 b | 71.5 b |
BUmung-2 | 38.8 c | 0.70 c | 11.1 c | 18.9 d | 81.8 a | 64.5 c |
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** | ** | ** | ** | ** | ** |
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CV (%) | 5.09 | 6.76 | 7.19 | 7.29 | 5.19 | 2.83 |
In a column, figures bearing the same letter(s) do not differ significantly at
Leaf area development at different ages in six mungbean varieties. Vertical bars represent LSD (0.05).
Changes in total dry mass at different ages in six mungbean varieties. Vertical bars represent LSD (0.05).
The crop growth rate (CGR) in four varieties (BARImung-4, BARImung-6, BINAmung-7, and BUmung-1) tended to increase with the advancement of stage till 55–65 DAS in 2010 and similar trend was observed in one variety of BINAmung-7 in 2011 (Figure
Pattern of crop growth rate in six mungbean varieties during their growth period. Vertical bars represent LSD (0.05).
The relative growth rate (RGR) declined with age in both years (Figure
Pattern of relative growth rate in six mungbean varieties during their growth period. Vertical bars represent LSD (0.05).
The pattern of net assimilation rate (NAR) in both seasons was not similar (Figure
Showing net assimilation rate of four mungbean genotypes at different ages. Vertical bars represent LSD (0.05).
The morphological (plant height and branch number plant−1), phenological (flowering duration and days to maturity), and reproductive characters (number of opened flowers plant−1 and reproductive efficiency) differed significantly among the studied cultivars (Table
The three varieties, BARImung-4, BINAmung-7, and BUmung-1, produced higher grain yield than the other three varieties, BARImung-6, BINAmung-6, and BUmung-2, due to production of higher number of pods plant−1 (Table
Yield components and seed yield in six mungbean varieties (Mean over two years).
Variety | Pods plant−1 (no.) | Pod length (cm) | Seeds pod−1 (no.) | 1000-seed weight (g) | Seed yield plant−1 (g) | Harvest index (%) |
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BARImung-4 | 36.0 b | 6.98 c | 10.30 | 33.4 c | 10.82 b | 26.65 b |
BARImung-6 | 15.4 d | 8.74 a | 10.45 | 53.9 a | 7.46 d | 33.94 a |
BINAmung-6 | 15.1 d | 8.68 ab | 10.40 | 51.7 a | 7.03 de | 31.81 a |
BINAmung-7 | 40.8 a | 6.53 d | 10.15 | 32.1 c | 11.57 a | 28.16 b |
BUmung-1 | 31.6 c | 7.17 c | 10.40 | 34.0 c | 9.68 c | 26.27 b |
BUmung-2 | 15.3 d | 8.42 b | 10.40 | 49.2 b | 6.78 e | 28.51 b |
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** | ** | NS | ** | ** | ** |
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CV (%) | 8.41 | 3.30 | 3.46 | 5.20 | 4.04 | 7.01 |
In a column, figures bearing the same letter(s) do not differ significantly at
From the results, it appeared that, for getting superior characters of yield components, a high yielding mungbean genotype should posses a relatively larger leaf area with superior growth parameters.
The authors acknowledge the authority of the Ministry of Science and Information & Communication Technology, Government of the People’s Republic of Bangladesh, for providing financial support to carry out the experiments from the Research and Development Project.