Microsoft Word - 7 Bangladesh Agron. J. 2017, 20(2): 67-74 PHYSIOLOPHYSIOLOPHYSIOLOPHYSIOLOGICALGICALGICALGICAL TRAITS TRAITS TRAITS TRAITS AND YIELD AND YIELD AND YIELD AND YIELD PERFORMANCEPERFORMANCEPERFORMANCEPERFORMANCE OF MUNGBEAN OF MUNGBEAN OF MUNGBEAN OF MUNGBEAN ((((Vigna radiataVigna radiataVigna radiataVigna radiata (L) Wilczek) (L) Wilczek) (L) Wilczek) (L) Wilczek) AS INFLUENCED BY LIGHT AS INFLUENCED BY LIGHT AS INFLUENCED BY LIGHT AS INFLUENCED BY LIGHT INTENSITIESINTENSITIESINTENSITIESINTENSITIES M. A. HossainM. A. HossainM. A. HossainM. A. Hossain1111****, M. A. Hasan, M. A. Hasan, M. A. Hasan, M. A. Hasan2222,,,, S. SikderS. SikderS. SikderS. Sikder2222, A. K. , A. K. , A. K. , A. K. M. M. B. ChowdhuryM. M. B. ChowdhuryM. M. B. ChowdhuryM. M. B. Chowdhury3333 and M. S. Sarkerand M. S. Sarkerand M. S. Sarkerand M. S. Sarker1111 Department of Crop Physiology and Ecology, Hajee Mohammad Danesh Science and Technology University, Dinajpur *Corresponding author, E-mail: asmaulhstu@gmail.com (Received: Received: Received: Received: 30 May 2017, Accepted:Accepted:Accepted:Accepted: 25 July 2017) Keywords: Keywords: Keywords: Keywords: Mungbean variety, chlorophyll, proline, yield AbstractAbstractAbstractAbstract An experiment was carried out at the Crop Physiology and Ecology Research Field, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur during the period from March to June 2016 to evaluate some physiological traits and yield performance of mungbean variety under different light intensities and to find out potential mungbean variety as intercrop. The experiment was laid out in a split -plot design with three replications. Three light intensities (L100 - full sunlight, L75- 75 % of full sunlight and L50- 50% of full sunlight) were assigned in the main plots and four varieties (BARl Mung-6, Binamoong8, Binamoong5 and BU Mug-4) in the subplots. White and red colour Mosquito nets were used for maintaining 75 and 50 percent of full sunlight. Light percentages of mosquito nets were measured by light meter (21YE35). Mosquito nets of different colors and pore size were used for maintaining 75 and 50 percent of full sunlight. The seed yield of BARI Mung-6 and Binamoong8 performing well in under partial shade condition but the grain yield of Binamoong5 and BU Mug-4 was reduced drastically under partial shade condition. Greater proline accumulation in leaf, higher leaf chlorophyll content, higher pods plant-1, higher seeds pod-1, greater seed size and better seed yield plant-1 under partial shade condition were contributed to better tolerance of BARI Mung-6 and Binamoong8 under low light stress. IntroductionIntroductionIntroductionIntroduction Mungbean (Vigna radiata (L) Wilczek) is one of the important pulse crops in Bangladesh. The agro ecological condition of Bangladesh is quite favorable for growing the crop. The crop is usually grown in kharif-I and kharif- II seasons with little or no inputs but it adds a lot to improve the soil health. Mungbean (Vigna radiata L.) has the potential to be used as profitable intercrop. But most of the grain legumes are sensitive to partial shading and often suffer from low light stress caused by associated tall crops (Miranda-Abilay and Lantican, 1982). The reduction in light reaching the legume canopy when intercropped with maize was about 30 - 50% of the total incoming radiation and began around 30-35 days after maize seeding (Polthanee and Changsri, 1999; Polthanee and Treloges, 2002; 2003). Shading causes decreasing of quantity and quality of the sun light intercept to the crop and it affects the productivity of the intercrops. Yield reduction by shading depends upon crop species as well as the degree of shading. The degree of shading is generally controlled by the nature, age and characteristics of upper storied crops. The yield of soybean was decreased by 25 under 47% shade cover in the field (Wahua and Miller, 1978) and it was decreased by 30 under 40% artificial shade (Lantican and Catedral, 1977). In contrast under 40% artificial shade the yield of mungbean was decreased by 70% (Lantican and Catedral, 1977). 68 Hossain et al. Shading leads to phenotypic change in their photosynthetic apparatus (Sundari, 2009). Shading reduced photosynthesis due to increase in stomatal and mesophyll resistance, transpiration, partioning of biomass from vegetative parts to economic parts (Nygren and Killomaki, 1993). However, responses of mungbean to change in light intensity may vary in different genotypes. Hence, developing variety adapted to low light condition is important and a need for selecting mungbean genotypes for shade tolerance. The mungbean genotypes could be the most tolerant and least decrease in grain yield, number of pods per plant, per cent leaf N and total stem N (Wahua and Miller, 1978). Therefore, the present investigation was conducted to find out the effect of reduced light intensities on some physiological traits of different mungbean varieties and to find out the low light tolerant varieties of mungbean. Materials and MethodsMaterials and MethodsMaterials and MethodsMaterials and Methods The experiment was conducted at Crop Physiology and Ecology Research Field, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur during the period from March to June 2016. The experiment was laid out in a split- plot design with three replications. Three light intensity treatments (L100 - full sunlight, L75- 75 % of full sunlight and L50- 50% of full sunlight) were assigned in the main plots and four varieties (BARI Mung-6, Binamoong-8, Binamoong5- and BUMug-4) in the sub-plots. White and red color Mosquito nets were used for maintaining 75 and 50 percent of full sunlight. Light percentages of mosquito nets were measured by light meter (21YE35). Chlorophyll content of the flag leaf at 48 days after sowing was estimated according to Witham et al. (1986). The proline content of the fully expanded youngest leaf was determined as Bates et al. (1973). For collecting data on yield components ten plants from each experimental unit were selected randomly at flowering stage. At maturity, pods were harvested three times by hand pickings. The harvesting of mungbean pods was started at 60 days after sowing (DAS) and ended at 80 DAS. Plant height, length of individual pod, pods plant-1, seeds pod-1, 1000-seed weight and yield plant-1 were also recorded from the ten randomly selected plants of each plot. The data were analyzed and the treatment means were compared using Tukey’s Test. Results and DiscussionResults and DiscussionResults and DiscussionResults and Discussion Proline contentProline contentProline contentProline content The interaction of light intensities and mungbean varieties influenced the proline content of leaf significantly at 50 DAS (Fig. 1). The maximum proline content was recorded in Binamoong8 (0.91 µmoles g-1 FW) with 50% of full sunlight which was statistically identical to those recorded in BARI Mung-6 (0.82 µmoles g-1 FW) with 50% of full sunlight, Binamoong 8 (0.79 µmoles g-1 FW) with 75% of full sunlight and Binamoong5 (0.76 µmoles g-1 FW) with 100% of full sunlight. The loweer proline content was recorded in BU Mug-4 (0.47 µmoles g-1 FW) with 100% of full sunlight which was statistically identical to BARI Mung-6 (0.53 µmoles g-1 FW) with 100% of full sunlight and BU Mug-4 (0.61 µmole g-1 FW) with 50% of full sunlight. The results regarding proline content revealed that proline level was increased with the reduction in light levels in BARI Mung- 6, Binamoong 8 and Binamoong 5. In BU Mug-4, proline content was increased at 75% of full sun light thereafter decreased at 50% of full sun light. 69 Physiological Traits and Yield Performance of Mungbean Fig.1. Leaf proline content as influenced by light intensities and mungbean varieties at different days after sowing. Means followed by different letter(s) differed significantly by Tukey’s test at P ≤ 5% level of probability. L100 = 100 % of full sunlight (open field control), L75 =75 % of full sunlight, L50 = 50% of full sunlight Chlorophyll contentChlorophyll contentChlorophyll contentChlorophyll content Chlorophyll a content in leaf was not influenced significantly by the interaction effect of light intensities and mungbean varieties (Table 1). Numerically, maximum chlorophyll a (0.32 mgg-1) was obtained in BU Mug-4 at L50 and the minimum (0.23 mgg -1) in Binamoong5 at L75. Chlorophyll b content in leaf was influenced significantly by the interaction effect where highest chlorophyll b (1.51 mgg-1) was observed both inBinamoong8 followed by BU Mug-4 at L75, which was statistically similar to Binamoog 8 (1.50 mgg-1) at L50, and Binamoong 5 (1.47 mgg-1) at L50, and (1.39 mgg -1) of same variety at L100 and BU Mug-4 (1.39 mgg -1) at L50. The lowest chlorophyll b was observed in BARI Mung-6 (1.24 mgg-1) at L100 which was statistically similar to those recorded in BU Mug-4 (1.25 mgg-1) at L100, BARI Mung-6 (1.29 mgg-1) at L75, Binamoong 8 (1.30 mgg -1)at L100, BARI Mung-6 (1.33 mgg -1) at L50 and Binamoong 5 (1.34 mgg-1) at L75. Similar trend was followed in Chlorophyll a to b ratio. Total chlorophyll content was influenced significantly by the interaction effect of light intensities and mungbean varieties (Table 1). The maximum total chlorophyll (1.81 mgg-1) was observed in Binamoong 8 at L50 whereas lower total chlorophyll was observed in BU Mug-4 (1.49 mgg -1) at L100..The overall results in chlorophyll content indicated that total chlorophyll content was increased due to reduction in light intensities. The increase in total chlorophyll content under partial shade was mainly due to reduction in chlorophyll b content. As chlorophyll a content remained more or less unchanged due to partial shade the chlorophyll a to b ratio in BARI Mung-6, Binamoong 8 and and Binamoong 5 with L75 and remained unchanged with L50 but in BU Mug-4 the ratio was remain unchanged L75 and increased with L50. Islam et al. (1993) and, Miranda- Abilay and Lantican (1982) found higher chlorophyll content in mungbean due to increased shading. Total chlorophyll content was influenced significantly by the interaction effect of light intensities and mungbean varieties (Table 1). The maximum total chlorophyll (1.81 mgg-1) was observed in Binamoong 8 at L50 whereas lower total chlorophyll was observed in BU Mug-4 (1.49 mgg -1) at L100..The overall results in chlorophyll content indicated that total chlorophyll content was increased due to reduction in light intensities. The increase in total chlorophyll content under partial shade was mainly due to reduction in chlorophyll b content. As chlorophyll a content 70 Hossain et al. remained more or less unchanged due to partial shade the chlorophyll a to b ratio in BARI Mung-6, Binamoong 8 and and Binamoong 5 with L75 and remained unchanged with L50 but in BU Mug-4 the ratio was remain unchanged L75 and increased with L50. Islam et al. (1993) and, Miranda-Abilay and Lantican (1982) found higher chlorophyll content in mungbean due to increased shading. Table 1. Chlorophyll a, chlorophyll b, chlorophyll a to b ratio and total chlorophyll content of leaf as influenced by light intensities and mungbean varieties Variety Light level Chl a (mgg-1) Chl b (mgg-1) Chl a to b ratio Total chl (mgg-1) BARI Mung- 6 L100 0.27 1.24 e 0.22 ac 1.50 cd L75 0.25 1.29 ce (4.03) 0.20 bd (-9.09) 1.54 bd (2.67) L50 0.28 1.33 be (7.23) 0.22 ac (0.00) 1.60 ac (6.67) Binamoong8 L100 0.27 1.30 ce 0.21ab 1.56 ad L75 0.27 1.51 a (16.15) 0.18 cd (-14.29) 1.78 a (14.10) L50 0.31 1.50 a (15.38) 0.21ab (0.00) 1.81 a (16.03) Binamoong5 L100 0.28 1.39 ac 0.20 bd 1.66 ab L75 0.23 1.34 be (-3.60) 0.17 d (-15.00) 1.57 ad (-5.42) L50 0.29 1.47 ab (5.76) 0.20bd (0.00) 1.76 ab (6.02) BU Mug- 4 L100 0.25 1.25 de 0.20 bd 1.49d L75 0.30 1.51 a (20.80) 0.20bd (0.00) 1.81 a (21.48) L50 0.32 1.39 ac (11.20) 0.23 a (15.00) 1.71 ab (14.77) CV(%) 9.97 3.43 4.34 2.92 In a column, means followed by different letter(s) differed significantly by Tukey’s test at P ≤ 5% level of probability. L100 = 100 % of full sunlight (open field control), L75 = 75 % of full sunlight, L50 = 50% of full sunlight Number of pods plantNumber of pods plantNumber of pods plantNumber of pods plant----1111 The interaction effect of light intensity and mungbean varieties on number of pods plant-1 was significant (Table 2). The maximum number of pods plant-1 (10.00) was observed in BARI Mung-6 with 100% of full sunlight, which was statistically similar to those recorded in BINA moong 5 (9.90) with 100% of full sunlight, Binamoong 8 (9.63) with 75% of full sunlight, BARI Mung-6 with 75% (9.57) and 50% (9.27) of full sunlight, Binamoong 8 with 50% (9.07) and 100% (8.97) of full sunlight and BU Mug-4 with 100% of full sunlight (8.93). The minimum number of pods plant-1 was observed in BU Mug-4 with 50% of full sunlight (6.07) which was statistically similar to that recorded in Binamoong 5 with 75% of full sunlight (7.03). Percent change from L100 values indicated that the number of pods plant -1 was reduced with reduction in light intensities in BARI Mung-6, Binamoong 5 and BU Mug-4 but it was even increased in Binamoong 8 under low light intensities. The reduction in number of pods plant-1 71 Physiological Traits and Yield Performance of Mungbean with the reduction of light intensities was more in BIinamoong and BU Mug-4 than that in BARI Mung-6. Table 2. Yield attributes of mungbean as influenced by light intensities and varieties Variety Light level Pods plant-1 Seeds pod-1 1000-seed wt (g) Seed yield (g plant-1) BARI Mung- 6 L100 10.00 a 8.57 ef 45.20 b 3.07 a L75 9.57 ab (-4.30) 9.15 bc (6.77) 47.23 a (2.03) 3.07 a (0.00) L50 9.27 ab (-7.30) 9.03 bd (5.37) 44.00 b (-2.65) 2.89 ad (-5.86) Binamoong 8 L100 8.97 ab 8.08 g 45.28 b 3.01 ac L75 9.63 ab (7.35) 8.62 ef (6.68) 44.09 b (-2.63) 2.86 bd (-4.98) L50 9.07 ab (1.11) 8.40 fg (3.96) 45.11 b (0.38) 2.84 cd (-5.64) Binamoong5 L100 9.90 a 9.20 bc 38.26 d 2.89 ad L75 7.03 de (-28.99) 9.32 b (1.30) 38.91 d (1.70) 2.47 e (-14.53) L50 7.70 cd (-22.22) 8.95 cd (-2.72) 40.49 c (5.83) 2.28 e (-21.11) BU Mug- 4 L100 8.93 ac 9.20 bc 45.40 b 3.00 ac L75 8.27 bd (-7.39) 9.73 a (5.76) 41.87 c (-9.85) 2.75 d (-8.33) L50 6.07 e (-32.03) 8.78 de (-4.56) 41.65 c (-8.26) 2.02 f (-32.67) CV (%) 5.97 1.25 1.26 2.66 In a column, means followed by different letter(s) differed significantly by Tukey’s test at P ≤ 5% level of probability. L100 = 100 % of full sunlight (open field control), L75 = 75 % of full sunlight, L50 = 50% of full sunlight Number of seeds podNumber of seeds podNumber of seeds podNumber of seeds pod----1111 The interaction effect of light intensities and mungbean varieties on number of seeds pod-1 was significant (Table 2). The maximum number of seeds pod-1 was recorded in BU Mug-4 (9.73) with 75% of full sunlight, which was followed by all other treatment combinations. The lowest number of seeds pod-1 was recorded in Binamoong 8 (8.08) with 100% of full sunlight, which was statistically similar to same variety (8.40) with 50% of full sunlight. Percent change from control (L100) values indicated that the number of seeds pod -1 was increased with reduction in light levels in BARI Mung-6 and Binamoong 8. On the other hand, in Binamoong 5 and BU Mug-4 it was increased in 75% of full sunlight but decreased in 50% of full sunlight. Thousand Thousand Thousand Thousand seeds seeds seeds seeds weight weight weight weight The interaction effect of light intensities and mungbean varieties on thousand seeds weight was significant (Table 2). The maximum seeds weight was observed in BARI Mung-6 (47.23 g) at L75, which was followed by all other treatment combinations while lowest seeds weight was observed in Binamoong5 (38.26 g) at L100, which was statistically similar to same variety (38.91 g) at L75. The results showed that increased or remained more or less unchanged due to 72 Hossain et al. low light intensities in BARI Mung-6, Binamoong 8 and Binamoong5 but it was reduced with the reduction in light intensities in BU Mug-4. Seed Seed Seed Seed yield yield yield yield The interaction effect of light levels and mungbean varieties on seed yield plant-1 (Table 2) and seed yield were significantly influenced (Fig.2). The maximum seed yield plant-1 was observed in BARI Mung-6 (3.07 g) both at L100 and L75, which was statistically similar to those obtained from Binamoong 8 (3.01 g) at L100, BU Mug-4 (3.00 g) at L100, BARI Mung-6 (2.89 g) at L50 and Binamoong (2.89 g) at L100. The lowest seed yield plant -1 was observed in BU Mug-4 (2.02 g) at L50. These results indicated that the seed yield plant - 1 was remain unchanged or decreased with the reduction in light levels but the reduction was more in Binamoong 5and BU Mug-4 than in BARI Mung-6 and Binamoong8. The maximum seed yield per hectare was recorded in BU Mug-4 with 100% of full sunlight (0.94 t ha-1) which was statistically similar to those recorded in Binamoong 8 with 100% of full sunlight (0.90 t ha-1). Lower grain yield per hectare was recorded in BU Mug-4 with 50% of full sunlight (0.52 t ha-1) which was statistically similar to Binamoong 5 with 50% of full sunlight (0.60 t ha-1). Fig. 2. Seed yield (t ha-1) as influenced by light intensities and mungbean varieties at different days after sowing. Means followed by different letter(s) differed significantly by Tukey’s test at P ≤ 5% level of probability. L100 = 100 % of full sunlight (open field control), L75-= 75 % of full sunlight, L50 = 50% of full sunlight The results in seed yield per hectare also indicated that the yield was remained statistically unchanged due to lower light levels in BARI Mung-6 and Binamoong 8 but in Binamoong 5 and BU Mug-4, the seed yield was reduced with the reduction in light levels. Seed yield of mungbean is attributed by number of pods, number of seeds per pod and seed size. These yield attributes were severely affected by degree of shading. Lantican and Catedral (1977), Laosuwan et al. (1992) and Miranda-Abilay and Lantican (1982) observed lower seed yield for shaded grown mungbean plant. Polthanee et al. (2011) showed that seed yield of soybean was significantly (p < 0.05) decreased under the low light intensity at 30% of natural light both in wet and dry season. Akhter et al. (2009) reported reducing the light intensity from 100 to 25% exerted variable quantity of reduction of dry seed yield plant-1 in different genotypes and the reduction of seed yield plant-1 was attributed to lower pod plant-1, seed pod-1 and smaller weight seed. Islam (1995) found pods per plant decreased with the increase of shading. 73 Physiological Traits and Yield Performance of Mungbean Stover yield plantStover yield plantStover yield plantStover yield plant----1111 The interaction effect of light levels and mungbean varieties on stover yield per plant was significant (Table 3). The maximum stover yield per plant was observed in Binamoong8 (6.71 g) at L50 which was statistically similar to BARI Mung-6 (6.05 g) at L50, Binamoong 8 (5.81 g) at L75, BINA Mung-5 (5.44 g) at L100, BU Mug-4 (5.33 g) at L75 and (5.20 g) at L50, Binamoong 5 (4.98 g) at L75, BU Mug-4 (4.93 g) at L100 and BARI Mung-6 (4.77 g) at L100. The lowest stover yield per plant was observed in Binamoong 8 (3.41 g) at L100 which was statistically similar to in BARI Mung-6 (3.65 g) at L75, Binamoong 5 (4.20 g) at L50, BARI Mung-6 (4.77 g) at L100, BU Mug-4 (4.93 g) at L100, Binamoong 5 (4.96 g) at L75, BU Mug-4 (5.20 g) at L50 and (5.33 g) at L75 and Binamoong 5 (5.44 g) at L100. Harvest index (%)Harvest index (%)Harvest index (%)Harvest index (%) The interaction effect of light levels and mungbean varieties on harvest index was significant (Table 3). The maximum harvest index was observed in Binamoong-8 (88.27) at L100 which was statistically similar to observed in BARI Mung-6 (84.11) at L75. The lowest harvest index was observed in BU Mug-4 (38.85) at L50 which was statistically similar to those observed in Binamoong 8 (3.65 g) at L50 and BARI Mung-6 (47.77) at L50. Table 3. Stover yield and Harvest index of mungbean as influenced by light levels and varieties Variety Light level Stover yield (g plant-1) Harvest index (%) BARI Mung- 6 L100 4.77 ad 64.36 b L75 3.65 cd (-23.48) 84.11 a L50 6.05 ab (26.83) 47.77 de Binamoong8 L100 3.41 d 88.27 a L75 5.81 ac (70.38) 49.23 d L50 6.71 a (96.77) 42.23 e Binamoong5 L100 5.44 ad 53.13 c L75 4.96 ad (-8.82) 49.80 d L50 4.20 bd (-22.79) 54.29 c BU Mug- 4 L100 4.93 ad 60.85 bc L75 5.33 ad (8.11) 51.60 cd L50 5.20 ad (5.48) 38.85 ef CV (%) 14.34 4.56 In a column, means followed by different letter(s) differed significantly by Tukey’s test at P ≤ 5% level of probability. L100 = 100 % of full sunlight (open field control), L75 = 75 % of full sunlight, L50 = 50% of full sunlight 74 Hossain et al. ConclusionConclusionConclusionConclusion The seed yield of mungbean var. BARI Mung-6 and Binamoong8 performing well in under partial shade condition but the seed yield of Binamoong5 and BU Mug-4 was reduced drastically under partial shade condition. Greater proline accumulation in leaf, higher leaf chlorophyll content, higher pods plant-1, higher seeds pod-1, greater seed size and better seed yield plant-1 under partial shade condition were contributed to better tolerance of BARI Mung-6 and Binamoong8 under low light stress. ReferencesReferencesReferencesReferences Akhter, N., M. M. Rahman, M. Hasanuzzaman and K. Nahar. 2009. Physiological response of garden pea (Pisum sativum L.) grown under different light environment. Bot. Res. Int. 2 (4): 304-309. Bates, L. S., R. P. Waldron and I. D. Teare. 1973. Rapid determination of free proline for water stress studies. Plant Soil 39: 205-207. Islam, S. M. T., F. Kubota, M. F. H. Mollah and W. Agata. 1993. Effect of Shading on the Growth and Yield of Mungbean (Vigna radiata L. Wilczek). J. Agron. Crop Sci. 171: 274–278. Lantican, R. M. and I. G. Catedral. 1977. Evaluation of legumes for adaptation to intensive cropping systems. I. Mungbean (Vigna radiata L. Wilczek). Philippine J. Crop Sci. 2: 62- 66. Laosuwan, P., S. Saengpratoom, S. Kaloowong and A. Thongsomsni. 1992. Breeding mungbean for shade tolerance, In "Proceedings of mungbean meeting", chiang Mai. Thailand. pp. 95- 100. Miranda-Abilay, R. and R. M. Lantican. 1982. Characters associated with yield performance of grain legume crops under partial shaded condition I. Mungbean (Vigna radiata). Philippine J. Crop Sci. 7(2): 88-93. Nygren, M. and S. Killomaki. 1993. Effect of shading on leaf structure and photosynthesis in young birches. Forest Ecol. Manag. 7(2) : 119-132. Polthanee, A. and R. Changsri. 1999. Effect of planting dates of mungbean on growth and yield in corn mungbean relay cropping under rainfed conditions in an up-land area of Northeastern Thailand. Thai J. Agric. Sci.32: 187-196. Polthanee, A. and V. Treloges. 2002. Growth and yield of mungbean cultivars in mungbean-corn relay inter-cropping systems. J. Inter. Soc. Southeast Asian Agric. Sci. 8: 1-14. Polthanee, A. and V. Treloges. 2003. Growth, yield and land use efficiency of corn and legumes grown under intercropping systems. Plant Prod. Sci. 6: 139-146. Polthanee, A., K. Promsaena and A. Laoken. 2011. Influence of low light intensity on growth and yield of four soybean cultivars during wet and dry seasons of Northeast Thailand. Agric. Sci. 2(2): 61-67. Sundari, T. 2009. Morphological and physiological characteristics of shading tolerant and sensitive mungbean genotypes. HAYATI J. Bio. Sci. 16(4): 127-134. Wahua, T. A. T and D. A. Miller. 1978. Effects of shading on the N2–fixation, yield, and plant composition of field-grown soybeans. Agron. J. 70: 387-392.