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Int.J.Curr.Microbiol.App.Sci (2017) 6(8): 51-59 International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 8 (2017) pp. 51-59 Journal homepage: http://www.ijcmas.com Original Research Article https://doi.org/10.20546/ijcmas.2017.608.008 Effect of Detopping Practice on Growth Parameters and Yield of Rabi Maize (Zea mays L.) B. Manju Bhargavi1*, B. Mukundam2, M. Malla Reddy1 and A. Sreenivas3 1 Department of Agronomy, Agriculture College, Jagtial, Prof. Jayashankar Telangana State Agricultural University, Telangana-505529, India 2 Agricultural research station, Nathanaipally, PJTSAU, Telangana-502313, India 3 Regional Agriculture Research Station, Palem, Mahabubnagar, PJTSAU, Telangana, India *Corresponding author ABSTRACT Keywords Detopping, Yield, SPAD readings, Growth parameters, Maize, LAI. Article Info Accepted: 04 June 2017 Available Online: 10 August 2017 A field experiment was conducted at College of Agriculture, Professor Jayashankar Telangana State Agricultural University, Hyderabad, India, in rabi 2014-15 to study the effect of different stages and different heights of detopping on growth parameters and yield components of maize (DHM-117). The experiment was laid out in a randomized block design comprising of a factorial combination of three stages of detopping viz., D 1-10 days after silking, D2-20 days after silking and D3-30 days after silking and three heights of leaves detopping viz., L1-detopping up to two leaves, L2-detopping up to four leaves, L3detopping up to six leaves with a control and replicated thrice. The results revealed that, higher plant height, number of leaves, LAI, dry matter production and yield were recorded in control (no-detopping) than the treatments. However, detopping at different stages did not show significant effect on these parameters, but highest dry matter production and yield were observed with D3 (detopping at 30 days after silking) and lowest in D1 (detopping at 10 days after silking). In case of different heights of detopping more plant height, no. of leaves, LAI, dry matter and yield were observed in L1 (detopping up to 2 top leaves) and lowest in L3 (detopping up to 6 top leaves). SPAD readings were not affected by either different stage of detopping nor different heights. It was inferred that leaves which are adjacent to the cob (especially two above the cob) has more leaf area to produce more dry matter hence yield. Introduction Maize (Zea mays L.) is the 3rd most important cereal, next to wheat and rice in the world in respect to area and productivity. The worldwide area of maize about 177 million hectares and production of 989 million tonnes with a productivity of 5.5 t ha-1 (2013-14) accounts about 64% of coarse grain and 27.1% of total cereal production (Commodity profile on maize, 2014). At present maize is being used to prepare more than 3000 different consumable products worldwide. In India 55% of grain produced currently is used for food purpose, about 14% for livestock feed, 18% for poultry feed, 12% for starch and 1% for seed. The expected demand for indigenous consumption and in international market is quite high. Therefore, level of production has to be substantially raised to meet its growing demand for food, feed and fuel. Being a C4-plant it has best 51 Int.J.Curr.Microbiol.App.Sci (2017) 6(8): 51-59 physiological efficiency and highest productivity potential among the cereals. This crop is known to be very responsive to inputs (fertilizer, seed, water and macro or micronutrients etc.) and better crop management. Another category of farmers who grow maize for seed production purpose are practicing detopping in order to facilitate the pollen to reach silk directly. Professor Jayashankar Telangana State Agricultural University, Rajendranagar, Hyderabad during rabi, 2014-15. The farm is geographically situated at an altitude of 542.3 m above mean sea level at 17019’N latitude and 78028’E longitude and falls under the Southern Telangana Agro-Climatic Zone of Telangana state. The experiment was laid out in randomized block design with factorial concept in three replications. Treatments comprised of three stages of detopping at different days after silking and three heights of leaves detopping with single control (no detopping). The details of treatments are furnished below. Factor I: Days after Silking: D1- 10 days after silking, D2- 20 days after silking, D3- 30 days after silking. Factor II: Detopping: L1- detopping up to two leaves, L2- detopping up to four leaves, L3- detopping up to six leaves and Control (No detopping). Maize seeds (DHM-117) were planted in the field with plot size of 5.4 m x 4.8 m with spacing 60 cm x 20 cm on ridges at 19th Oct, 2014. The soil texture was sandy loamy with pH 7.5, EC 0.163 dSm-1 and organic carbon 0.40%. The soil was low in available nitrogen (175 kg ha-1), medium in available phosphorus (36 kg ha-1) and high in available potassium (342 kg ha-1). For all treatments fertilizer was applied on the basis of recommended dose of N: P: K was 200:80:80 kg ha-1. The silking came at 60 DAS and treatments were implemented at 10 days interval. Herbicide and pesticide were used to control the weeds and pests. Every 10-12 days interval, irrigation has given based on soil moisture content. Crop was harvested at 15th Feb 2015. Growth parameters such as nondestructive sampling parameters like plant height, number of leaves and SPAD were recorded from five plants were selected randomly and tagged in each treatment plot. Similarly, at each sampling interval five plants for destructive sampling (LAI, Dry matter) were uprooted from two rows on either side between border and net plots Another group of farmers are also practicing detopping in maize to avoid lodging problem in fertile soils and especially in areas like coastal districts. Detopping refers to nipping or the removal of terminal portion from the uppermost node to improve the yield through greater functioning of remaining leaves by arresting unnecessary growth, decreasing mutual shading of leaves, enhancing light interception, increasing nutrient uptake, decreasing competition between the tassel and cob for available plant nutrients, diverting plant nutrients to the reproductive part which aids in better source-sink relationship and better cob development (Esechie and AlAlawi, 2002). Maize tassel removal may affect light penetration in the canopy, especially if the crop is a C4 plant needs high light requirement. Tassel removal may increase the seed yield and seed quality. Interaction of defoliation and tassel removal may also affect assimilate distribution between reproductive and vegetative organs. Hence the present study was carried out with an objective of to study the effect of different stages and heights of detopping on growth parameters in relation to yield in maize hybrid DHM117. Materials and Methods The present investigation was carried out at College Farm, College of Agriculture, 52 Int.J.Curr.Microbiol.App.Sci (2017) 6(8): 51-59 earmarked for the purpose. Yield has taken from net plot and converted into kg ha-1. removal). Whereas, less number of leaves (8.5) were obtained from L3 (detopping up to 6 top leaves removal) at 90 DAS and at harvest. The result of present investigation regarding different heights of detopping was in line with Wilhelm et al., (1995) who reported that the average number of leaves remaining above ear after treatment application ranged from 5.4 for control to 1.4 for tassel + 4 leaves removal and declined linearly with the number of leaves removed. The interaction effect of different stages and heights of detopping on number of leaves was not found significant. In comparison of control vs. treatments, control (no detopping) recorded significantly more number of leaves (15.5) over other treatments. Results and Discussion Plant height (cm) The results (Table 1) revealed that different stages of detopping didn’t show significant influence on plant height. But different heights of detopping had significant influence on plant height. Maximum plant height (192.9 cm) was recorded in L1 (Detopping upto top 2 to leaves) and significantly superior to L2, and L3 (Detopping up to top 4 and 6 leaves respectively), in turn these are significantly differ with each other and L3 recorded the lowest plant height (150.6 cm). The decrease in plant height might be due to the termination of apical dominance (Brar et al., 2000). These results are in accordance with the findings of Tadesse et al., (2012), Usman et al., (2007), Firoz et al., (2010), Hallikeri et al., (2010) and Srisailam (2010). The interaction effect of different stages and heights of detopping on plant height was not found significant at any stage of the crop growth. In comparison of control vs. treatments, highest plant height was registered in control (215.2 cm) and significantly superior to all other treatment combinations. Leaf Area Index (LAI) Experimental data on LAI influenced by effect of different stages and heights of detopping was presented in table 1. Different stages of detopping on LAI were not found significant. Detopping at different heights showed significant influence on LAI. At harvest maximum LAI (4.16) was observed with L1 (detopping up to 2 top leaves) and was significantly superior over L2 and L3 (Detopping up to top 2, 4, and 6 leaves, respectively), whereas, L3 recorded lowest LAI (2.85). Removing of leaves either 3 or 4 had a greater impact on LAI than removal of 1 and 2 leaves because of the difference in size of leaves; leaves nearest ear were larger than those further from the ear (Dwayer and Stewart, 1986; Keating and Wafula, 1992). Effects of leaf removing on LAI were different according to the intensity of defoliation and leaf position (Barimavandi et al., 2010). The results were in conformity with the findings of Wilhelm et al., (1995), Saihkouhian (2012) and Esechie and ALAlawi (2002). The interaction effect of different stages and heights of detopping on leaf area index was not found significant at all stage of the crop growth. In comparison of Number of leaves Experimental data on number of leaves influenced by effect of different stages and heights of detopping was presented in table 1. During the period of investigation, different stages of detopping did not exert significant influence on number of leaves. Reduction in number of leaves is due to removal of tops and gradual senescence of older leaves. Different heights of detopping had significant on effect of number of leaves. Higher number of leaves (12.1) were obtained from L1 (detopping up to 2 tops removal) over L2 and L3 (detopping up to 4 & 6 top leaves 53 Int.J.Curr.Microbiol.App.Sci (2017) 6(8): 51-59 control vs. treatments, more LAI (4.70) was obtained from control (no detopping) and which was significantly superior over other treatments. Decrease in LAI by 11.4%, 28.9% and 39% with L1 (detopping up to 2 top leaves), L2 (detopping up to 4 top leaves) and L3 (detopping up to 6 top leaves), respectively when compared to control (no detopping). compared to later stages. Barimavandi et al., (2010) found that 92 DAS, dry matter increasing found descent lane under defoliating two leaves on the top of ear. Different types of leaf clipping have various influences on dry matter accumulation when leaf clipping occurs at the primary stage of grain development (Wang, 1996). Among different heights of detopping, significantly higher dry matter (1588 g m-2) was found to be associated to L1 (detopping up to 2 top leaves) at harvest, and which was statistically at par with L2 (detopping up to 4 top leaves removal). Whereas, least (1538 g m-2) amount belonged to L3 (detopping up to 6 top leaves) at harvest. Even though LAI reduced with number of leaf removal, but dry matter production was not affected or slightly affected by detopping up to 2 and 4 top leaves, whereas more reduction in dry matter was observed with detopping up to 6 top leaves (L3). SPAD chlorophyll meter readings Experimental data on SPAD chlorophyll meter readings was analyzed statistically and presented in table 1. The effect of different stages of detopping and different heights of detopping on SPAD chlorophyll meter readings was not found significant. The results were in accordance with findings Bijanzadeh and Emam (2010) who reported that flag leaf chlorophyll content was not affected by source restriction. During the period of investigation, interaction effect of different stages and heights of detopping and in comparison of control vs. treatments did not exert significant influence on chlorophyll content. This reduction in DM might be due to loss of photosynthetic area in L3 (detopping up to 6 top leaves) because no leaves above the cob when plant was detopped up to 6 top leaves. These results are in conformity with findings of Barimavandi et al., (2010) who found that 92 DAS, dry matter increasing found descent lane under defoliating two leaves on the top of ear. Probable reason for this incident is suitable position of upper leaves for perfect absorption of sun light and superior photosynthesis. Another reason for this stem is an important secondary resource in maize and this act efficiently under stress condition. Dry matter production (g m-2) Data pertaining to effect of different stages and heights of detopping on dry matter (DM) production was analyzed statistically (Table 2) and found to vary significantly. Different stages of detopping had more effect on dry matter. Significantly more dry matter (1641 g m-2) was observed in D3 (detopping at 30 days after silking) at harvest over D1 (detopping at 10 days after silking). However D2 (detopping at 20 days after silking) was found to be on par with D3, whereas, D1 recorded the lowest dry matter at this stage (1440 g m-2). The reason for decreasing in dry matter with D1 (detopping at 10 days after silking) might be due to early reproductive phase was more sensitive to source restriction, any stress causes at this stage has negative impact on dry matter production and also yield The amount of retransmission of stored assimilates from stem to grain depends on intensity of defoliation and position of leaves. So that the removing above leaves causes exceed retransmission of assimilates to grain. Consequently, removing of these leaves is lead to decrease in photosynthetic materials and little production of dry matter. 54 Int.J.Curr.Microbiol.App.Sci (2017) 6(8): 51-59 Table.1 Plant height, no. of leaves, leaf area index and SPAD meter readings of maize as influenced by different stages and Heights of detopping Treatment L1 194.7 193.9 190.0 192.9 D1 D2 D3 Mean Control Factor (I) Factor (II) Interaction Control vs. Treatment SEm± 1.56 1.35 2.70 3.31 Plant height (cm) L2 L3 Mean 161.9 152.0 169.5 164.0 153.5 171.1 164.7 146.4 165.9 163.5 150.6 215.2 CD (P=0.05) NS 2.85 NS 9.89 Number of leaves L1 L2 L3 Mean 12.5 10.1 8.6 10.4 11.8 10.3 8.7 10.3 12.0 11.2 8.3 10.5 12.1 10.5 8.5 15.5 SEm± CD (P=0.05) 0.18 NS 0.16 0.35 0.31 NS 0.38 1.23 Leaf area index L2 L3 Mean 3.37 2.88 3.47 3.32 2.85 3.43 3.32 2.82 3.43 3.34 2.85 4.70 SEm± CD (P=0.05) 0.02 NS 0.02 0.04 0.04 NS 0.05 0.15 L1 4.17 4.14 4.16 4.16 SPAD meter readings L1 L2 L3 Mean 52.63 56.03 52.66 53.77 55.90 54.40 51.30 53.86 49.90 53.03 50.93 51.28 52.48 54.48 51.63 52.93 SEm± CD (P=0.05) 1.31 NS 1.31 NS 2.27 NS 2.78 NS Factor (I): Different stages of detopping: D1- 10 days after silking, D2- 20 days after silking and D3- 30 days after silking Factor (II): Different heights of detopping: L1- Detopping up to 2 top leaves, L2- Detopping up to 4 top leaves, L3- Detopping up to 6 top leaves Control- No detopping Table.2 Dry matter production and grain yield of maize as influenced by different stages and heights of detopping Treatment D1 D2 D3 Mean Control Factor (I) Factor (II) Interaction Control vs. Treatment L1 1484 1639 1642 1588 SEm± 6.67 5.78 11.56 14.15 Dry matter (g m-2) L2 L3 1469 1368 1636 1607 1639 1641 1581 1538 1653 CD (P=0.05) 14.02 12.14 24.28 42.05 Mean 1440 1627 1641 L1 5288 7197 7218 6568 SEm± 55.9 48.4 96.9 118.7 Grain yield (kg ha-1) L2 L3 5238 4168 7195 6872 7198 7196 6544 6078 7226 CD (P=0.05) 117.6 101.8 203.7 352.9 Factor (I): Different stages of detopping: D1- 10 days after silking, D2- 20 days after silking and D3- 30 days after silking Factor (II): Different heights of detopping: L1- Detopping up to 2 top leaves, L2- Detopping up to 4 top leaves, L3- Detopping up to 6 top leaves Control- No detopping 55 Mean 4898 7088 7204 Int.J.Curr.Microbiol.App.Sci (2017) 6(8): 51-59 The reason of declining in the amount of dry matter in plant might be due to elimination of young leaves at anthesis stage which leads to diminished amounts of dry matters accumulation in plant. Removing of these leaves have intensive effect on dry weight in diminishing order. The present experimental findings are in accordance with the results of Jalilian and Delkoshi (2014), safari et al., (2013) and Tilahun (1993). The results of interaction effect of different stages and heights of detopping showed that maximum dry matter was obtained from detopping at 30 days after silking (D3) up to 2 top leaves (L2) and it was on par with removal of 4 (L2), 6 (L3) top leaves detopping at 30 days after silking. And which was statistically at par with detopping up to 2, 4 top leaves+ at 20 days after silking (D2). In turn minimum dry matter occurred in detopping at 10 days after silking (D1) with removal of 6 top leaves (L1). When compared control vs. treatments, control (no detopping) recorded higher dry matter (1653 g m-2) at harvest and which was statistically similar with detopping at 30 days after silking (D3) with removal of 2 (L1), 4 (L2), and 6 (L3) top leaves and detopping at 20 days after silking (D2) with removal of 2 and 4 top leaves. Reduction in dry matter in D1 might be due to defoliation treatments imposed when the number of grains had been established reduced the source/sink ratio and resulted in a sharp decrease in stem soluble carbohydrates (Wesgate and Boyer, 1985). The above experimental finding was in accordance with the results of Woldeamlak et al., (2006). was comparable with D2 (detopping at 20 days after silking), and both the treatments were found to be significantly superior over D1 (detopping at 10 days after silking). Lowest was recorded in D1 (4898 kg ha-1). The above experimental findings indicated that delay in detopping was associated with increased trend in grain yield. Reduction of yield as a sequence of leaf removal from maize plant when they were in early reproduction phase has been reported by many researchers (Afarinesh, 2005 and Borras and Otegui, 2001). Topping at two weeks after anthesis did not have any adverse effect on grain yield (Sarvestani et al., 2001). These results were in conformity with Emam et al., (2013), Woldeamlak et al., (2006), Mimber and Susylowati (1995). Among different heights of detopping, significantly higher grain yield (6568 kg ha-1) was obtained in L1 (detopping up to 2 top leaves) and was found to be par with L2 (detopping up to 4 top leaves), in turn L3 (detopping up to 6 top leaves) recorded the lowest grain yield (6078 kg ha-1). The results of present study showed that reduction in grain yield as removal of number of leaves above the cob increased. There is a direct relationship between grain yield and the number of leaves removed (Tilahun, 1993). In any crop, the degree of yield reduction is directly proportional to the percentage of leaf area destroyed. The loss of functional leaf area results in loss of photosynthetic area of plant and reduce the assimilate availability (Walpole and Morgan, 1970). The superior effect of top leaves on the yield depends on their extent of sunlight absorption. It was reported that apex leaves of ear could transfer about 23-91% of photosynthetic matters to the cobs. (Anderew and Peterson, 1984). The grain stores photosynthates via three main resources including current photosynthesis in the leaves, photosynthesis in green parts of plants excluding leaves and transferring from the storing parts (Hashemi and Maraashi, 1993). Grain yield (kg ha-1) Experimental data on grain yield was presented in table 2. The difference in grain yield of maize was conspicuous with different stages of detopping. The highest grain yield (7204 kg ha-1) was obtained with D3 (detopping at 30 days after silking) and which 56 Int.J.Curr.Microbiol.App.Sci (2017) 6(8): 51-59 The findings are in accordance with those of Barimavandi et al., (2010), Jalilian and Delkhoshi (2014), safari et al., (2013). Interaction effect of different stages and heights of detopping showed that significantly higher grain yield (7218 kg ha-1) was recorded in 30 days after silking (D3) and detopping up to 2 to leaves (L1) and was on par with detopping up to 4 (L2), 6 (L3) top leaves and detopping at 20 days after silking (D2) with detopping up to 2 and 4 top leaves. On the other hand D1 (detopping at 10 days after silking) with 2, 4 and 6 top leaves removal recorded lowest grain yield (5288 kg ha-1, 5238 kg ha-1 and 4168 kg ha-1, respectively). In early stages of detopping up to 2, 4 and 6 top leaves grain yield reduced, but in later stages detopping up to 2, 4 top leaves did not altered the grain yield. However, when plants were detopped above the cob (L3) drastically reduced the grain yield. These results were in conformity with Emam et al., (2013), Mimbar and Susylowati (1995) and Subedi (1996). when compared with control vs. treatments, higher grain yield (7226 kg ha-1) was recorded in control (no detopping), as compared to less grain yield noticed in detopping at 10 days after silking (D1) with detopping up to 2, 4 and 6 top leaves and reduction of yield in percentages were 26.8%, 27.5% and 42.3% respectively. On other hand control produced significantly comparable grain yield with detopping at 30 days after silking with 2, 4 and 6 top leaves removal (reduction of yield in percentages were 0.1%, 0.3% and 0.4% respectively) and detopping at 20 days after silking with 2 and 4 top leaves removal (reduction yield in percentages were 0.4% and 0.42% respectively). detopping at 20 and 30 days after silking up to 2, 4 and 6 top leaves. 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