International Journal of Agriculture and Crop Sciences. Available online at www.ijagcs.com IJACS/2013/5-20/2459-2465. ISSN 2227-670X ©2013 IJACS Journal
The Effect of Source-Sink Restriction and Plant Density Changes on the Role of Assimilate Remobilization in Corn Grain Yield Fatemeh Falihzade1, Mani Mojadam2, Shahram Lack3* 1. Department of Agronomy, Science and Research Branch,Islamic Azad University (IAU), Khouzestan, Iran 2. Department of Agronomy, Islamic Azad University, Ahvaz, Iran 3. Department of Agronomy, Science and Research Branch,Islamic Azad University (IAU), Khouzestan, Iran *corresponding author email:
[email protected] ABSTRACT: In order to study the effect of source-sink restriction and various plant density on the remobilization of assimilates stored in vegetative parts to the ear corn hybrid single cross 704, a split-block experiment as randomized complete block design with three replications was carried out in Ahvaz in summer 2011. In this research the source restriction was imposed through defoliation of the leaves and the sink restriction was imposed by cutting theear at the end of pollination stage as the main factor including the defoliation of the upper leaves of the corn, defoliation of lower leaves, removal of 50% of the ear, and no defoliation and no ear removal (control) in main plots and the plant density as the sub factor including 60000 plants per hectare, 75000 plants per hectare (control) and 90000 plants per hectare in sub plots. Results indicated that source-sink restriction and plant density had significant effect on the rate, contribution, and efficiency of photosynthesis and assimilates remobilization. The highest grain yield by 868.67 g/m2belonged to the control treatment (no defoliation or ear removal)due to producing more grains and the heavier weight of 1000-grain and the lowest grain yield by 646.33 g/m 2 belonged to the treatment with the removal of 50% of ear due to significant decrease of grains in the corn and the number of grains per square meter in spite of the increase of the weight of 1000-grain. The treatment with 50% removal of ear had the lowest rate and contribution of remobilization (9.9%) because of the sink restriction, but the treatment with the defoliation of the upper leaves of the ear had the highest rate and contribution of remobilization (39.31%) due to significant decrease of rate and contribution of photosynthesis (60.69%).In this experiment, the increase of plant density increased the grain yield significantly because of the increase of the grains per square meter and the weight of 1000-grain despite the decrease of grains per ear so that the density of 90000 plants per hectare had the highest grain yield by 886.33 g/m2. This treatment devoted the least contribution of photosynthesis (71.74%) and the most contribution of remobilization (28.26%) in the production of grain yield to itself due to close competition among the plants especially further shadowing of the leaves. The interactive effect of the factors showed that the treatment with the defoliation of upper leaves of the ear and with density of 90000 plants per hectare had the highest contribution of remobilization (43.37%) and the lowest contribution of photosynthesis (56.63%) in grain weight which indicated that the decreasing effect of removal of the upper leaves of the ear and the increase of plant density on photosynthesis through the decrease of leaf area and the increase of leaves shadowing. Keywords: Source-sink restriction, Plant density, Remobilization, Grain yield, Corn INTRODUCTION Improving the maize yield has been possible in recent years by using modified kinds of maize and in addition, optimum agricultural programs such as proper density of plant and sowing model have been effective in the increase of maize grain yield (Siadat, 1994). These factors will affect assimilates production and their storage in vegetative organs and grains by changing the crop access to production resources especially the sunlight. The place where assimilates are loaded in the plant is called source and the place where assimilates are unloaded is called sink. The movement of assimilates from the source to the sink (consumption or storage place) depends on the capacity of the source to produce them on one hand and the capacity of the sink to consume them on the other hand. If there is not a balance between them, the yield will decrease. A proper
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balance between the source and the sink is an important element to achieve favorable yields. The potential of the source and the sink in plants depends on two factors of genetic capacity and environmental conditions (Khodabandeh, 1993). One of the first available researches on the source changes was conducted by Duncan in 1965. He stated that pollination stage is the most sensitive stage to defoliation and concluded that the removal of all the leaves at 50% anthesis would reduce the yield by 92% while the removal of the leaves at dough grain stage would have no effect on the ultimate grain yield (Ciriol and Anderson, 1996). By examining the status of dry matter accumulation affected by defoliation it was known that the removal of the upper leaves of the ear immediately after 50% anthesis reduced the number of the grains and delayed defoliation reduced the grain weight and consequently the grain yield (Esechie, 1992). Stem reserves are able to fix the rate of grain filling and to neutralize the fluctuations caused by photosynthesis; in other words, by translocation of stem reserves to grains various stresses including those caused by defoliation will be neutralized (Ciriol and Anderson, 1996). Assimilates resulted from the ear leaves and five upper leaves and five lower leaves are transferred to the grains. However, assimilate distribution model is very flexible. If upper leaves are removed or placed in the shade, the lower leaves will be feeding the grains (Barzegari, 1994). Jafar Tayari et al., (2010) reported that corn SC. 704 has the least source restriction. Leaves are considered as the source and growing organs are considered as the sink. The mobilization of assimilates from the source to the sink depends on capacity of the source to produce assimilates and capacity of the sink to consume them. If there is not a balance between them, the yield will decrease. A proper balance between the source and the sink is an important element to achieve favorable yields.If the reduction of source through the removal of leaves does not affect the yield the destination is restrictive. Often the grain yield restriction is considered in terms of relative importance of the source and the sink and the system of assimilate mobilization from the source to the sink is less emphasized. Therefore, whenever the source and the sink are not restrictive but the capacity of mobilization system is restrictive in the route of the source and the sink, the existence of a lot of starch and sugar in the stem and the leaves sheath during the harvest indicates the restriction in assimilate mobilization or storage system (Khayat and Gohari, 2009). Lack of reaction to the shadowing or removal of some leaves or in other words lack of response to any changes in the ratio of source to sink indicates the sink restriction in normal circumstances (Ma et al., 1995) while the increase of the weight of grain in response to the decrease of sink ratio indicates that due to insufficient photosynthesis grains haven’t achieved their maximum growth in normal circumstances or in other words the source is restricted (Gustavo and Savin, 1994; Ma et al., 1995). Serious competition in high densities of corn leads to the increase of leaf area and crop height to overcome crops nearby in attaining production sources especially light which results in the increase of dry matter accumulation in area unit and the decrease of photosynthesis efficiency while in lower densities even though the dry matter of single plant is more, due to the decrease of plants in area dry matter of growing organs decreases and there is less competition between plants and thus photosynthesis efficiency increases (Alavi Fazel, 2010). The finding of Pany (1984) indicated that in high densities, the upper leaves of the ear are more important than the lower ones and the removal of the higher leaves of the ear in high densities causes serious changes in photosynthesis. In studying the effect of density on corn Gozubenli (2010) said that dry matter of stem decreased as the density increased. Seyed Sharifi et al., (2009), Mobasser et al., (2007), Zhang et al., (2006), and Xue et al., (2002) declared that the increase of density increased the grain yieldsignificantly and the highest grain yield was obtained at density of 10 plants per square meter. Alavi Fazel (2010) reported that the increase of density caused the significant decrease of rate, contribution, and efficiency of photosynthesis but the significant increase of rate, contribution, and efficiency of remobilization. The findings of Dehdashti and Riahinia (2008) and Alavi Fazel (2010) showed that the increase of density decreased the rate of photosynthesis during the filling stage of grains due to the leaves shadowing and acceleration in their aging; moreover, high density of plants reduces the photosynthesis efficiency of the leaves during the grain filling stage by increasing the competition during the vegetative growth stage. Low density also decreased the rate of photosynthesis due to the lack of proper use of solar energy and the loss of some part of it in the distance between the plants, but the density of 85000 plants per hectare with better completion conditions and application of production sources and more continuity of leaf area had the higher rate of photosynthesis. Lack (2006), Alavi Fazel (2010), and Hashemi and Herbert (1992) reported that the increase of density resulted in the early aging of the leaves and the decrease of leaves efficiency because of the increase of competition among the plants and more shadowing of the leaves. Moreover, due to the decrease of dry matter accumulation in single plant and the decrease of photosynthesis the plant faced the sharp decrease of florets inoculation and abortion and thus the number of grains sharply decreased in the corn; in other words, through the reduction of grains, it was possible for the remaining single grains to gain weight and it seems like that due to the decrease in the sinks and the low rate of assimilates resulted from photosynthesis , the rate of assimilate remobilization increased. By increase of plant density in area unit, the contribution of photosynthesis decreased in final weight of grain. The increase of competition, leaves aging and the reduction of leaves photosynthesis efficiency especially due to the shadowing of the leaves over each other and the increase of plant density and the use of some assimilates in breathing of the lower parts of the plant reduced the contribution of current 2460
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photosynthesis in high densities. On the contrary, lower densities had higher contribution of photosynthesis due to less shadowing of the leaves and the decrease of competition among the plants and the longer continuity of the leaf area. He reported that the lower densities had more photosynthesis efficiency than the higher densities. Lack (2006) declared that the increased efficiency of assimilate remobilization with the increase of density was due to the increase of remobilization and the decrease of photosynthesis efficiency. Zhang et al., (2006) stated that photosynthesis efficiency and growth of ear highly depends on the effect of canopy characteristics in vertical distribution of light within the canopy. The increase of plant density is a way to absorb more light entering the canopy. MATERIALS AND METHODS In order to study the effect of source-sink restriction and various plant density on the assimilates remobilization from vegetative parts to grain, a split-block experiment as randomized complete block design with three replications was carried out in the experimental field of Shahid Salemi located in the Northeast of Ahvaz in summer 2011. In this research the source restriction was imposed through defoliation of the leaves and the sink restriction was imposed by cutting the ear as the main factor including defoliation of the upper leaves of the ear (S1), defoliation of lower leaves (S2), removal of 50% of the ear(S3) , and no defoliation and no ear removal (control)(S4) in main plots and the plant density as the sub factor including 60000 plants per hectare (D1) , 75000 plants per hectare (control) (D2) and 90000 plants per hectare (D3) in sub plots with three replications. The source restriction began through the removal of the leaves from the epiglottis based on treatment areas at the end of pollination stage and before the beginning of grain filling stage and the sink restriction began with cutting the ear into halves at the same stage. Based on the findings of Lack (2006), 7 days after the silk emergence when the maximum dry matter is accumulated in vegetative organs of the maize (at the beginning of silk’s getting brown). After eliminating the margins 6 plants from the sampling lines of each subplot was taken their total dry weight was measured after putting them in the oven at 72°C. At the end of growth stage the grain yield and the dry weight of vegetative organs (the difference between the total dry matter yield and the grain yield) was measured and the above features were calculated by means of equations of Ehdaie (1998), Van Sanford and Mackown, 1987), Papacosta and Gayanas (1991). Rate of remobilization (g/m2) = dry weigh of vegetative organs at the beginning of silk’s getting brown 2 (g/m ) – dry weight of vegetative organs at maturity stage (g/m 2) Efficiency of remobilization(g/g) = Rate of remobilization (g/m2)/ Dry weigh of vegetative organs at the beginning of silk’s getting brown (g/m 2) Contribution of remobilization (%) = (Rate of remobilization (g/m 2) / grain yield (g/m 2)) ×100 2 2 2 Rate of current Photosynthesis(g/m ) = Grain yield (g/m ) - Rate of remobilization (g/m ) 2 Efficiency of current Photosynthesis (g/g) = Rate of current Photosynthesis (g/m ) / dry weight of vegetative organs at maturity stage (g/m 2) Contribution of Photosynthesis (%) = 100 – contribution of remobilization (%) Variance analysis of individual and interactive effect of factors was done by means of MINITAB and the means of treatment were compared through low significance difference test (LSD). RESULTS AND DISCUSSION According to analysis of variance the effect of source-sink restriction on grain yield was significant at 1% probability level (Table 1). The comparison of the means indicated that the treatmentwithout the removal of leaves and ear (control) by producing 868.67 g/m2 had the highest grain yield and other levels of this treatment had significant difference with control and the treatment with the removal of 50% of the ear had the lowest grain yield by producing 646.33 g/m 2 (Table 2). Dry matter accumulation can be the main reason of grain yield decrease. It seems like cutting the ear cannot make the increase of grain yield and grain weight possible which might be due to grains restriction to make use of the source. ANOVA results indicated that plant density at 1% probability level had a significant effect on the grain yield (Table 1). The treatment of 90000 plants per hectare 2 by producing 886.33 g/m had the highest grain yield and the treatment of 60000 plants per hectare by 2 producing 588.25g/m had the lowest grain yield. Comparison of means through LSD method showed that densities of 60000 and 90000 plants per hectare had significant difference with control treatment (75000 plants per hectare) at 1% probability level (Table 2). In this experiment it seems that the increase of biological yield through the increase of light absorption and better use of production sources resulted in higher grain yield and in spite of the decrease of grains in corn, the grain yield increased because of the increase of grains in area unit and 1000-grain weight in relation to lower densities. The interactive effect of treatments on the grain yield at 1% probability level was significant (Table 1). The treatment without removal of the leaves and ear with 2 density of 90000 plants per hectare had the highest grain yield by producing 1968 g/m and the treatment of 2 cutting the ear with density of 60000 plants per hectare by producing 516 g/m had the lowest grain yield. 2461
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Among the treatments, the one with density of 95000 plants per hectare and without defoliation of leaves and ear had the highest grain yield because of the lack of restriction in production and sufficient sinks for storage and also receiving more sunlight while the treatment of cutting the ear in the lowest density had the least grain yield due to the lack of perfect use of sunlight and lower density of plants per area unit and also the remarkable reduction of grains. The obtained results are consistent with the finding of Lack (2006) and Alavi Fazel (2010). Rate, Efficiency, and Contribution of Remobilization With regard to ANOVA results, the effect of source-sink restriction on rate, efficiency, and contribution of remobilization was significant at 1% probability level (Table 1) and the comparison of the means (Table 2) showed that the difference between various treatment levels and control was significant at 1% probability level. Defoliation of upper and lower leaves of the ear , since the leaves are the most important photosynthesis organ, reduce the production of nutrients which could lead to the increase of assimilate remobilization in relation to the control treatment and indicates the source restriction due to leaves defoliation. That is, because of production restriction due to leaves defoliation, reproduction of assimilates increases to compensate for a part of this deficit. The rate of remobilization decreases in the treatment of cutting the ear because of the restriction of sinks or grains. Therefore, the simultaneous restriction of source and sink in control treatment can be referred to in general. The treatment of cutting the ear had the lowest efficiency and remobilization contribution among the treatments due to the decrease of remobilization rate which indicates the restriction of the source. In the treatment with defoliation of upper and lower leaves of the ear there was a significant increase in remobilization contribution in comparison to the control treatment because of the removal of the main photosynthetic organs. It sees that as the upper leaves of the ear are younger and have more photosynthetic capability the area of theses leaves has increased the contribution of remobilization more than the lower leaves of the ear. The increase of efficiency and contribution of remobilization in treatments with the removal of upper and lower leaves of the ear in relation to the control treatment can indicate the source restriction in such conditions. Lower efficiency and contribution of remobilization in cutting the ear in comparison to the control treatment could be another indicator of the sink restriction in this experiment because in case of the lack of sink restriction further increase of grain weight was possible through the increase of remobilization contribution. ANOVA results indicated that the effect of plant density on rate, efficiency, and contribution of remobilization was significant at 1% level (Table 1). According to the table of the means, the density of 60000 plants per hectare had the lowest and the density of 90000 plants per hectare had the highest rate, efficiency and contribution of remobilization (Table 2). By increase of density due to closer competition among the plants after canopy is closed and more shadowing of the leaves over each other, the rate of remobilization increases significantly; in other words, in higher density the plant has more rate of remobilization in order to compensate for the negative effects of further competition which restricts production. Further rate of remobilization contribution by the increase of density shows further restriction of production sources and the need of the plant to compensate for the source restriction through assimilate remobilization. The interactive effect of source-sink restriction and plant density on the rate, efficiency, and contribution of remobilization was significant at 1% level (Table 1). Restriction of sinks and less competition among the plants in treatment S3D1has reduced remobilization in relation to other treatments and on the contrary, treatments S2D3 and S2D3 had the highest rate and contribution of remobilization due to further density and more competition in spite of the removal of some leaves. It seems that any factor, which limits the main parts of the plant which are, engaged in photosynthesis i.e. the leaves and effective factors of production especially the light, will increase the rate and contribution of remobilization through the reduction of plant photosynthesis. The lowest rate and contribution of remobilization belonged to treatment S3D1because of the existence of complete leaves and the lowest density on one hand, and the restriction of remaining grains to make use of nutrients after cutting the ear on the other hand. These results are consistent with findings of Lack (2006) and Alavi Fazel (2010). Rate, Efficiency and Contribution ofCurrent Photosynthesis According to ANOVA results,the effect of source-sink restriction on rate, efficiency, and contribution of photosynthesis was significant at 1% level (Table 1). Comparison of means by LSD method indicated that all treatments were significantly different from the control treatment at 1% level (Table 2). The complementary role of photosynthesis and remobilization in the filling stage of grain is shown in this experiment. By change of photosynthesis rate, remobilization was affected as well. In the treatment with defoliation of upper leaves of the earit seems that the removal of young active leaves which have better chance to access more light at the upper parts of stem reduced the rate of photosynthesis significantly and the removal of the lower leaves of the ear showed less reduction of photosynthesis than the upper leaves. However, through defoliation of leaves the contribution of photosynthesis in the treatment with the removal of upper leaves of the ear reduced 21 % and in treatment with the removal of lower leaves of the ear reduced 17% in relation to the control treatment. Although this reduction increased the remobilization contribution, it couldn’t compensate for the grain yield in relation to the control treatment. In treatment with cutting 50% of the ear in spite of higher rate of photosynthesis in 2462
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comparison to the treatments with defoliated leaves it seems that the contribution of photosynthesis is less than that of control treatment because of the restriction of grains to absorb assimilates, i.e. although the contribution of photosynthesis in final weight of grain was more in this treatment, it was not possible to store produced nutrients in the grains; therefore, the sink restriction and the interactive effect of source and sink reduced the rate of photosynthesis in this treatment. Reduction of rate of photosynthesis and remobilization in the treatment with cutting the ear shows more restriction of the source within the experiment conditions which has finally caused the significant decrease of grain yield in the treatment. Slight increase of grain weight in this treatment approves of other results. The effect of plant density on rate, efficiency, and contribution of photosynthesis was significant at 1% level (Table 1). By increase of density and due to further leaf area the rate of photosynthesis significantly increased even though the contribution of photosynthesis reduced because of more serious competition in high densities.The increase of grain yield due to increase of density could be the result of efficiency of photosynthesis and remobilization. Through the increase of density it was possible to make optimal use of production sources and it was possible to achieve higher grain yield in case of providing all necessary conditions for production in the experiment. The higher grain yield by the increase of density resulted from the increase of grain per area unit and weight of 1000-grain which indicated the increase of photosynthesis efficiency and remobilization by the increase of plant density. The interactive effect of source-sink restriction and plant density on rate, efficiency, and contribution of photosynthesis was significant at 1% level (Table 1). Comparison of means by LSD method showed that there was a significant difference between different levels of treatments and control at 1% level. Treatment S4D3 had higher rate and more efficiency of photosynthesis due to better use of production sources; on the contrary, treatment S1D1 had the lowest rate of photosynthesis which reduced the grain yield due to the removal of young, active, upper leaves of the ear and lack of optimal use of production sources due to lower density. The results of the findings by Seyed Sharifi et al., (2009), Lack (2006), Alavi Fazel (2010), and Zhang et al., (2006) are consistent with these results. Table 1.the results of variance analysis of effective traits in remobilization of stored materials in – per grain shown in mean square Sources of variables replication Source and sink limitation Main plots errors (Ea) Plant density Interactive Effects ofSource and sink limitation and Plant density Sub plots errors (Eb) Coefficient %))variation
Degree of Freedom 2 3 6 2
Grain yield ns
254
Rate of Remobilization 56
ns
0.000133 **
79535** 479 266562**
6
Efficiency of Remobilization
Contribution of Remobilization
ns
1.19
ns
Rate of Current photosynthesis 205
ns
Efficiency of Current photosynthesis ns 0.0012
Contribution of Current photosynthesis ns 1.19
0.0.056647**
1766.96**
144092**
0.053**
1766.96
82
0.000044
0.42
227
0.0003
0.42
34338
0.009358**
70.95**
109868**
0.0125**
70.95**
1909
0.000947**
5.77**
10709**
0.0056**
5.77**
31
0.000062
0.12
121
0.00039
0.12
2.9
5.39
0.47
1.65
4.8
0.47
9773** 16
226 2.04
**
89394
**,*, ns respectively significant at the one percent and five percent lev el, and no significant difference.
CONCLUSION Source-sink restriction and plant density had significant effect on grain yield and rate, contribution, and 2 efficiency of photosynthesis and remobilization. The highest grain yield by 868.67 g/m belonged to the control treatment (no defoliation or ear removal) due to producing more grains and the heavier weight of grain and the lowest grain yield by 646.33 g/m 2 belonged to the treatment with the removal of 50% of ear due to significant decrease of number of grains in spite of the increase of the weight of grain. The treatment with 50% removal of ear had the lowest rate and contribution of remobilization because of the sink restriction, but the treatment with the defoliation of the upper leaves of the ear had the highest rate and contribution of remobilization due to significant decrease of rate and contribution of photosynthesis. The increase of plant density increased the grain yield significantly because of the increase of the grains per square meter and the weight of grains so that the density of 90000 plants per hectare had the highest grain yield by 886.33 g/m 2. This treatment devoted the least contribution of photosynthesis and the most contribution of remobilization in the production of grain yield to itself due to close competition among the plants especially further shadowing of the leaves. The interactive effect of the factors showed that the treatment S4D3 had the highest grain yield (1086g/m 2) and S1D3treatment 2463
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had the highest contribution of remobilization (37.43%) and the lowest contribution of photosynthesis (63.56%) in grain weight which indicated the decreasing effect of removal of the upper leaves of the ear by increase of plant density on photosynthesis through the decrease of leaf area and the increase of leaves shadowing. Table 2. Comparison of the mean of the effect of source and sink limitation and plant density on remobilization of preserved materials in vegetative organs to grain by LSD method
Treatment
Efficiency of Remobilizati on (gram per gram)
Contribution of Remobilizati on (percent)
Rate of Current photosynthesi s (gram per square meter)
Efficiency of Current photosynt hesis (gram per gram)
Contributio n of Current photosynt hesis (percent)
Grain yield (gram per square meter)
Rate of Remobilization (gram per square meter)
707.67
230.35
0.22
39.1
427.32
0.33
60.69
727.22
261.34
0.21
35.52
465.88
0.37
64.48
646.33
64.72
0.05
9.9
581.61
0.44
90.10
868.67
160.62
0.11
18.12
708.04
0.51
81.88
38.24
15.82
0.011
1.13
26.32
0.03
1.13
588.25 737.83 886.33 17.93
140.04 188.37 264.86 6.64
0.12 0.14 0.17 0.009
23.42 25.42 28.26 0.41
448.21 549.46 639.47 13.12
76.58 74.55 71.74 0.41
Grain yield (gram per square meter)
Rate of Remobilization (gram per square meter)
Efficiency of Remobilizati on (gram per gram)
Contribution of Remobilizati on (percent)
Rate of Current photosynthesi s (gram per square meter)
0.38 0.42 0.44 0.023 Efficiency of Current photosynt hesis (gram per gram)
Source and sink limitation Cutting upper leaves of the maize (S1) Cutting lower leaves of the maize (S2) Cutting 50 percent of maize (S3) No cutting of maize leaves (S4) (control) LSD(one percent) Plant Density 60000 plants in ha(D1) 750000 plants in ha(D2) 90000 plants in ha(D3) LSD(one percent)
Treatment
Contributio n of Current photosynt hesis (percent)
Source and sink limitation Cutting upper leaves of the maize (S1) Cutting lower leaves of the maize (S2) Cutting 50 percent of maize (S3) No cutting of maize leaves (S4) (control) LSD(one percent) Plant Density 60000 plants in ha(D1) 750000 plants in ha(D2) 90000 plants in ha(D3) LSD(one percent)
707.67
230.35
0.22
39.1
427.32
0.33
60.69
727.22
261.34
0.21
35.52
465.88
0.37
64.48
646.33
64.72
0.05
9.9
581.61
0.44
90.10
868.67
160.62
0.11
18.12
708.04
0.51
81.88
38.24
15.82
0.011
1.13
26.32
0.03
1.13
588.25 737.83 886.33 17.93
140.04 188.37 264.86 6.64
0.12 0.14 0.17 0.009
23.42 25.42 28.26 0.41
448.21 549.46 639.47 13.12
0.38 0.42 0.44 0.023
76.58 74.55 71.74 0.41
LSD: the minimum of significant difference of the mean between the two treatments at the level of 1 percen
Treatment
Source and sink limitation Cutting upper leaves of the maize (S1) Cutting lower leaves of the maize (S2) Cutting 50 percent of maize (S3) No cutting of maize leaves (S4) (control) LSD(one percent) Plant Density 60000 plants in ha(D1) 750000 plants in ha(D2) 90000 plants in ha(D3) LSD(one percent)
Grain yield (gram per square meter)
707.67 727.22 646.33 868.67
Contribution of Remobilizati on (percent)
Rate of Current photosynthesi s (gram per square meter)
Efficiency of Current photosynt hesis (gram per gram)
Contributio n of Current photosynt hesis (percent)
0.22
39.1
427.32
0.33
60.69
261.34
0.21
35.52
465.88
0.37
64.48
64.72
0.05
9.9
581.61
0.44
90.10
Rate of Remobilization (gram per square meter)
Efficiency of Remobilizati on (gram per gram)
230.35
160.62
0.11
18.12
708.04
0.51
81.88
38.24
15.82
0.011
1.13
26.32
0.03
1.13
588.25 737.83 886.33 17.93
140.04 188.37 264.86 6.64
0.12 0.14 0.17 0.009
23.42 25.42 28.26 0.41
448.21 549.46 639.47 13.12
0.38 0.42 0.44 0.023
76.58 74.55 71.74 0.41
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Treatment
Source and sink limitation Cutting upper leaves of the maize (S1) Cutting lower leaves of the maize (S2) Cutting 50 percent of maize (S3) No cutting of maize leaves (S4) (control) LSD(one percent) Plant Density 60000 plants in ha(D1) 750000 plants in ha(D2) 90000 plants in ha(D3) LSD(one percent)
Rate of Remobilization (gram per square meter)
Efficiency of Remobilizati on (gram per gram)
Contribution of Remobilizati on (percent)
Rate of Current photosynthesi s (gram per square meter)
Efficiency of Current photosynt hesis (gram per gram)
Contributio n of Current photosynt hesis (percent)
230.35
0.22
39.1
427.32
0.33
60.69
261.34
0.21
35.52
465.88
0.37
64.48
64.72
0.05
9.9
581.61
0.44
90.10
160.62
0.11
18.12
708.04
0.51
81.88
38.24
15.82
0.011
1.13
26.32
0.03
1.13
588.25 737.83 886.33 17.93
140.04 188.37 264.86 6.64
0.12 0.14 0.17 0.009
23.42 25.42 28.26 0.41
448.21 549.46 639.47 13.12
0.38 0.42 0.44 0.023
76.58 74.55 71.74 0.41
Grain yield (gram per square meter)
707.67 727.22 646.33 868.67
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