Study of Radiation Use Efficiency of Autumnal Sugar Beet under Variable Irrigation Regimes and Nitrogen Rates Management
Subject Areas : Research On Crop Ecophysiology
MOSTAFA
HOSSEINPOUR
1
(Sugerbeet Research Department, Safi-Abad Agricultural research center, AREO, Dezful, Iran.)
SEYED HOSSEIN
MAHMOODI NEZHAD DEZFULLY
2
(Soil and Water Research Department, Safi-Abad Agricultural research center, AREO, Dezful, Iran.)
ALIREZA
PAKNEZHAD
3
(Soil and Water Research Department, Safi-Abad Agricultural research center, AREO, Dezful, Iran.)
Keywords:
Abstract :
Original Research |
Research on Crop Ecophysiology Vol.11/1 , Issue1 (2016), Pages:18 -26
|
Study of Radiation Use Efficiency of Autumnal Sugar Beet under Variable Irrigation Regimes and Nitrogen Rates Management
Mostafa Hosseinpour1*, Seyed Hossein Mahmoodi Nezhad Dezfully2 , Alireza Paknezhad2,
1-Sugerbeet Research Department, Safi-Abad Agricultural research center, AREO, Dezful, Iran.
2- Soil and Water Research Department, Safi-Abad Agricultural research center, AREO, Dezful, Iran. 09163469321 & 09163442780.
*Corresponding author Email: harm558@yahoo.com
Received: 8 August 2015 Accepted: November 2015
Abstract
The present study investigates the radiation-use efficiency (RUE) of the autumn-sown sugar beet under variable irrigation regimes and nitrogen rates management in two independent experiments during 2009-2010 and 2010-2011at Safi-Abad Agricultural Research Center (SARC) in Dezful. The irrigation experiment includes five irrigation water levels as a ratio of plant water requirements (25%, 50%, 75%, 100% and 125%). The nitrogen experiment included five nitrogen levels (0, 60, 120, 180 and 240 KgNha-1). Both experiments were carried out using randomized complete blocks design with four replications. In both experiments intercepted radiation, leaf area index (LAI), and total dry matter were measured in two-week intervals during the growth season. Results showed no significant differences in radiation-use efficiency (RUE) under different irrigation regimes and nitrogen rates. Increased amount of water and nitrogen increased LAI. There was a 3rd degree polynomial function between the RUE and days after emergence (DAE) and between LAI and DAE. In both experiments, the peak of RUE and LAI occurred at approximately 110 and 173 DAE, respectively.
Keywords: Radiation use efficiency, Nitrogen, irrigation, Leaf area, Autumn-sown sugar beet
Introduction
Solar radiation provides the energy required for photosynthesis, carbohydrate distribution, and growth of plant parts (Holt, 1995), and plays an important role in determining the energy balance (Hoogenbum, 2000; Pearcy et al., 1996). In addition, total amount of photosynthesis materials existed in the plant depends on the level of received light (Webb, 1997). Different amounts of sugar beet radiation-use efficiency (RUE) have been reported in the literature from 2.96 to 3.76 μg/J (Holt, 1995) and from 3.16 to 4.12 μg/J (Milford et al, 1985). RUE less than 1.93 μg/J (Scott et al,1973) to 1.44 μg/J under no- irrigation conditions, 1.66 μg/J under irrigation conditions (Brown et al, 1987) and 1.3-1.6 μg/J have been reported in different northern European regions (Werker and Jaggard, 1998; Wright et al,1997). The average RUE for sugar beet can be considered as 1.72g of total dry matter per Mega Joule (MJ) (Scott and Jaggard, 1993). Werker and Jaggard (1998) showed that sugar beet RUE decreased over the growth season and this trend was accelerated under no-irrigation conditions. Although nitrogen has major impact on the reception of light and the leaves color, the experiments conducted in Bromze Barn station over 1982-1989 have shown that nitrogen does not change the conversion factor (Scott and Jaggard, 1993; Burkart et al, 2009; Malnou
et al, 2008). In other crop such as wheat application of different amount of nitrogen have same effect on RUE (Garcia et al, 1988). Nitrogen and irrigation are two main factors that affect sugar beet yield and quality. Both of them can increase or decrease radiation interception through leaf growth rate and leaf expansion. A few numbers of researchers have studied RUE under autumn-sown cultivation conditions especially under different amount of nitrogen and irrigation regimes. On the other hand there is not information about how RUE changes by irrigation water and nitrogen in this region. Therefore, this experiment was carried out aiming for investigating the effect of two important factors (nitrogen and irrigation) on the RUE of autumn-sown sugar beet over 2009-2010 and 2010-2011 at SARC in Dezful.
Material and methods
Experiment Site
This study was done in two crop years, i.e. 2009-2010 and 2010-2011, at SARC in Dezful, with average annual precipitation of 345mm. The soil of the site is a silty clay loam with field capacity of about 22% (by weight percentage), permanent wilting point of about 12%, and specific weight of 1.62 g/cm3. Every year, two independent experiments were carried out in one field. In the first experiment, five irrigation regimes as a percentage of water requirements of the sugar beet plant (25%, 50%, 75%, 100% and 125%) and in the second experiment, five nitrogen levels (0, 60, 120, 180 and 240 KgNha-1) were studied with four replications in a randomized complete block design. Based on the soil test, 150 kg ha-1 of potassium sulphate, 90 kg ha-1of triple superphosphate, half of the nitrogen (90 Nkgha-1in irrigation experiment), and half of the nitrogen treatments (in nitrogen experiment) of urea source were scattered manually in related plots. Sowing date of irrigation and nitrogen experiments was October 19, of each year. In both experiments, seeds of “Rasoul” monogerm sugar beet cultivar were planted in two rows 60 cm apart on 120 cm width ridges, using an experimental planter. Both experiments were conducted using T-tape drip irrigation method. T-tape lines were placed between each of the two planted rows; so that, their distance from each of these row was 30 cm. Pores distance on the tape was 30 cm, with capacity of 4 liters per hour per meter on the tape. In irrigation experiment, to control the pressure and irrigation level, subordinate pipes of each treatment were connected to a set of counter, valve, and pressure gauge. Each plot, in irrigation and nitrogen experiments, included three ridges (six planted rows) with the length of 13m.The water requirement of sugar beet calculated by pan evaporation method (FAO, 1984) as displayed by equation 1.
ETc = Kp*Kc*E
Where ETc is evapotranspiration of crop (mm day-1), Kc is crop coefficient and E is pan evaporation (mm day-1). Sugar beet plants were thinned at 4-6 leaves stage in 20 cm distance on planted rows and the other half of nitrogen fertilizer was distributed manually on both sides of T-tape lines next to the planted rows. In the irrigation experiment, treatments were applied from March 11, of each year and irrigation before that was the same for all treatments. Interval of irrigation was between 3 to 4 days. In nitrogen experiment irrigation conducted based on supply of 100% plant water requirement.
Plant Measurements
In both experiments, from 65 days after emergence (DAE) to final harvest (late May), biweekly plants were harvested at 0.5m2 area of each plot in 4 replications. The harvested plants were divided into four parts including leaf, petiole, crown and root, and their dry weight were determined by placing 100g of each inside an oven for 72 hours. Therefore, total dry weight included leaf, petiole, crown and root dry weights. Leaf area was determined by weight method. In this method fresh weight of ten randomly sampled from each plot was measured. After that the shape of them was drawn on standard paper. The weight and area of standard paper was determined. Hence the area of ten leaves determined by extrapolation. From the relationship between leaf dry weight and area of leaves the leaf area index was calculated.
In nitrogen experiment, canopy percentage was measured using a 120×60 cm metal frame with 288, 5×5 squares. Since the application of the treatments in irrigation experiment was after completion of canopy coverage (March 11), this trait was not included in this experiments. Up to March 11, all irrigation treatments were considered identical in terms of cultural practices.
Radiation use efficiency (RUE)
RUE (μgJ-1) was calculated using the ratio of total dry matter (μgcm-2) to the received solar radiation (Jcm-2) by sugar beet plant in a certain time (equation 2) (Rinaldi and Vonella, 2006).
RUE = TDM/Rgi (equ 2)
TDM= total dry matter
Rgi= received radiation, which was calculated by equation 3.
Rgi = Rgo[1-e (-kGLAI) ] (equ 3)
Where, Rgo is total radiation (MJm-2day-1) and K stands for extinction coefficient of light which is 0.53 for sugar beet (Khayamim et al, 2002). Total radiation was measured daily, using a thermopile pyranometer (wave length range of 305-2800nm) at the weather station next to the experimental field. RUE was calculated during the growth season, using the total dry matter (TDM) difference between two consecutive sampling divided by the amount of intercepted cumulative radiation at the time between two samplings. Seasonal RUE was calculated by dividing the amount of TDM at the time of final harvest by the intercepted cumulative radiation from emergence to final harvest.
Statistical Procedures
Analysis of variance based on randomized complete block design was used for each experiment separately to determine the effect of different irrigation regimes and nitrogen amounts on RUE, total dry matter, and intercepted commutative radiation, In each experiment, treatment mean for above traits were compare using Duncan's multiple range test. Daily values of RUE at sampling dates were interpolated by third-order polynomial functions.
Results and Discussion
Weather
Figure 1 shows the monthly maximum and minimum temperatures during two growth seasons. In the second year, temperature was about 2.3ºC lower than the first year, on average, and the minimum temperature was approximately 2.9ºC lower than the first year, from December to March. This implies that the second year was cooler than the first year up to that date; while, the maximum and minimum temperatures in the second year, from late March to late June were 1.3̊C and 1̊C higher than the first year, respectively. The evaporation rates during the growth season in the first and second years were 811 and 876 mm, and the precipitation were 291 and 333 mm, respectively. Figure 2 shows the monthly cumulative total radiation during the growth season. Radiation pattern was similar in both years, but the minimum total radiation in the first and second year occurred in January and December respectively. The maximum total radiation occurred in June in both years. The total cumulative amount of radiation, from October to June that is the growth duration of sugar beet in this region was almost equal in both years (4075.7 and 4158.3 MJm-2).
Canopy
Canopy coverage for different nitrogen rates is presented in Figure 3. The daily coverage for different nitrogen, i.e. 0, 60, 120, 180, and 240 Nkgha-1 were 0.79, 0.85, 0.91, 0.94, and 0.96 percent from 43 to 84 DAE, respectively. Therefore, Canopy coverage completed at 127, 117, 110, 107, and 104 DAE, respectively. Canopy coverage difference between 0 and 240 KgNha-1, from emergence to about 84 DAE was 13%. Thus, increased use of nitrogen through affecting leaf area expansion accelerates canopy completion and allows more reception of solar radiation. In figure 4, increased level of intercepted radiation, due to the application of nitrogen, is clearly observable. After 84 DAE when the canopy coverage difference between 0 and 240 KgNha-1 levels is almost 13%, its radiation reception difference is almost equal (about 15%). These results are in consistent with those reported by Scot and Jaggard (1993) that increased use of nitrogen increase intercepted radiation. In terms of canopy percentage (Figure 3) and the amount of intercepted radiation (Figure 4) the levels of 120, 180, and 240 KgNha-1 and 0 and 60 KgNha-1are at the same level. The maximum light interception occurred at 175 DAE for all nitrogen levels. These coincide with the highest LAI which show by Figure 5 and Figure 7.
Leaf area and RUE during the growth season
Radiation use efficiency in sugar beet during crop cycle expressed as DAE under different irrigation water supply and amount of nitrogen. The third-order polynomial functions of daily values at sampling data are represented in (Table 1). In irrigation experiment up to 138 DAE, (before applied treatments), the LAI and RUE were the same in all of them. After that, increased use of water increased LAI and RUE were (Figures 5 and 6). The peaks of LAI and RUE obtained in mid of April (173 DAE) and in late December (110 DAE), respectively. The maximum RUE (1.79μgJ-1) occurred before appling the treatments when LAI was 3. This trend is the same as founding by Rinaldi and Vonella (2006). In nitrogen experiments LAI did not show any difference up to 110 days (Figure 7), when radiation-use efficiency was maximized (1.66μgJ-1). From this time, differences among nitrogen levels were clearly obvious and increased nitrogen use increased leaf area and radiation-use efficiency (Figure 8).
Table 1. Third order polynomial function between the RUE and DAE and between LAI and DAE under different nitrogen rates and irrigation regimes
Treatments | Functions | R2 | |||||||||
Irrigation as a ratio of plant water requirement |
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25 % | LAI = -0.031DAE3 + 0.322DAE2 - 0.145DAE + 1.294 | 0.83 | |||||||||
RUE= 0.025DAE3 - 0.422DAE2 + 1.935DAE - 1.1695 | 0.85 | ||||||||||
50 % | LAI = -0.033DAE3 + 0.354DAE2 - 0.201DAE + 1.276 | 0.81 | |||||||||
RUE = 0.022DAE3 - 0.377DAE2 + 1.802DAE - 1.068 | 0.96 | ||||||||||
75 % | LAI = -0.057DAE 3 + 0.783DAE 2 - 2.192DAE + 2.542 | 0.88 | |||||||||
RUE = 0.021DAE 3 - 0.355DAE 2 + 1.692DAE - 0.952 | 0.91 | ||||||||||
100 % | LAI = -0.062DAE 3 + 0.871DAE 2 - 2.601DAE + 2.974 | 0.89 | |||||||||
RUE = 0.018DAE 3 - 0.306DAE 2 + 1.472DAE - 0.731 | 0.64 | ||||||||||
125 % | LAI = -0.073DAE 3 + 1.030DAE 2 - 3.198DAE + 3.509 | 0.91 | |||||||||
RUE = 0.018DAE 3 - 0.308DAE 2 + 1.499DAE - 0.767 | 0.60 | ||||||||||
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Nitrogen KgN.ha-1 |
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0 | LAI= -0.043DAE 3 + 0.572DAE 2 - 1.473DAE + 1.196 | 0.89 | |||||||||
RUE = 0.005DAE 3 - 0.132DAE 2 + 0.848DAE - 0.163 | 0.66 | ||||||||||
60 | LAI = -0.042DAE 3 + 0.571DAE 2 - 1.539DAE + 1.475 | 0.91 | |||||||||
RUE = 0.004DAE 3 - 0.102DAE 2 + 0.738DAE - 0.086 | 0.54 | ||||||||||
120 | LAI = -0.035DAE 3 + 0.435DAE 2 - 0.83DAE + 1.099 | 0.90 | |||||||||
RUE = 0.005DAE 3 - 0.114DAE 2 + 0.789DAE - 0.143 | 0.58 | ||||||||||
180 | LAI = -0.053DAE 3 + 0.694DAE 2 - 1.642DAE + 1.770 | 0.84 | |||||||||
RUE = 0.004DAE 3 - 0.110DAE 2 + 0.774DAE - 0.081 | 0.49 | ||||||||||
240 | LAI = -0.055DAE 3 + 0.706DAE 2 - 1.564DAE + 1.573 | 0.88 | |||||||||
RUE = 0.006DAE 3 - 0.126DAE 2 + 0.849DAE - 0.181 | 0.56 | ||||||||||
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Table2. Summary of combined ANOVA for total dry matter, radiation-use efficiency, and received radiation at the final harvest of sugar beet in irrigation experiment
Radiation use efficiency | Received radiation | Total dry matter | DF | Sources of variation |
0.004 ns | **287520.5 | *648938.3 | 1 | Year |
0.024 | 17694.9 | 91946 | 6 | Error |
0.044 ns | 16426.9 ns | 167505.2 ns | 4 | Irrigation |
0.013 ns | 6568.2 ns | 100055.2 ns | 4 | Year*Irrigation |
0.019 | 7692.2 | 98399.3 | 24 | Error |
11.1 | 3.95 | 11.4 |
| C.v.(%) |
Ns: non-significant, * , ** : significant at p < 0.05 and 0.01, respectively
Table 3. Summary of combined ANOVA for total dry matter, radiation-use efficiency, and received radiation at the final harvest of sugar beet in nitrogen experiment
Radiation use efficiency | Received radiation | Total dry matter | DF | Source of variation |
0.365 ns | **1870103.6 | *9628957.5* | 1 | Year |
0.081 | 17335.8 | 387527.3 | 6 | Error |
0.018 ns | 140306.3** | 316615.7* | 4 | Nitrogen |
0.035 ns | 105319.7** | 389686.2* | 4 | Year*Nitrogen |
0.019 | 4161.7 | 103212.2 | 24 | Error |
10.7 | 2.9 | 11.2 |
| C.v. |
Ns: non-significant, * , ** : significant differences at P < 0.05 and 0.01, respectively
Radiation use efficiency, light reception, and dry matter yield at final harvest
Tables 2 and 3 show combined ANOVA for total dry matter, received radiation, and radiation- use efficiency at final harvest irrigation and nitrogen experiments in respectively. In both tests, year had significant impact on dry matter and received radiation at the final harvest. There was no significant differences between irrigation treatments in terms of above traits, which is in agreement with the results of Rinaldi and Venla (2006). Nitrogen levels showed significant differences only in terms of total dry matter and the received light. There was no significant difference between them in terms of radiation- use efficiency, which confirms Scott and Jaggard (1993) indicanting nitrogen has no impact on the conversion factor. Irrigation treatment means for studied traits were statisticaly in the same group (Table 4). Therefore, under the condition of this experiment in a range of 4099 to 8953 m3ha-1 water consumption, the performance of total dry matter, received radiation and radiation- use efficiency of autumn- sown sugar beet was not significantly different. However, the means of nitrogen treatments were in statistical different in terms of total dry matter and the received radiation, but they were not statistically different in terms of radiation- use efficiency (Table 5), showing the same conversion of radiation to biomass at different nitrogen level.
Table 4. Mean comparison for total dry matter, radiation- use efficiency, and received radiation at the final harvest of sugar beet during two years of irrigation experiment
Radiation use efficiency (μgj-1) | Cumulative received radiation at final harvest (MJm-2 ) | Mean of received radiation (MJm-2day-1) | Mean of radiation (MJm-2day-1) | Total dry matter at final harvest (gm-2) | Consumed Water (m3ha-1) | Irrigation regimes As a Ratio of plant water requirement |
1.29 a | 2147 b | 9.98 | 13.93 | 2766 a | 4099 | 25 |
1.18 a | 2232 ab | 10.38 |
| 2621 a | 5375.7 | 50 |
1.15 a | 2267 a | 10.55 |
| 2592 a | 6524.6 | 75 |
1.3 a | 2216 ab | 10.31 |
| 2881 a | 7791.3 | 100 |
1.29 a | 2243 ab | 10.43 |
| 2907 a | 8953.2 | 125 |
* In each column, means that have at least one common letter are not significantly different based on. using Duncan’s multiple range tests.*
Table 5. Mean comparison of total dry matter, radiation-use efficiency, and the received light at final sugar beet harvest in nitrogen experiment
Radiation use efficiency (μgj-1) | Cumulative Received Radiation at Final Harvest (MJm-2) | Mean of Received Radiation (MJm-2day-1) | Mean of Radiation (MJm-2day-1) | Total Dry Matter at Final Harvest (gm-2) | Nitrogen (kgha-1) |
1.22 a | 2038 c | 9.48 | 14.14 | 2561 b | 0 |
1.35 a | 2073 c | 9.64 |
| 2812 ab | 60 |
1.29 a | 2253 b | 10.48 |
| 2906 ab | 120 |
1.31 a | 2274 b | 10.58 |
| 2986 a | 180 |
1.31 a | 2341 a | 10.89 |
| 3082 a | 250 |
* In each column, numbers that have at least one common letter are not significantly different based on during the two years of experiment, using Duncan’s multiple range tests.*
Conclusion
The results of this study demonstrated that the used irrigation and nitrogen treatments had no effect on RUE of autumn- sown sugar beet. But nitrogen affects canopy coverage, total dry matter and received radiation significantly. Increased nitrogen application increased the three characters. But different irrigation water as a drip method at the late season had no impact on these traits. The highest RUE (1.7µgj-1) was obtained at 110 DAE in both experiments.
Acknoeledgments
I would like to express my profound gratitude to all the participants for their co-operation and for their immense faith they reposed in me.
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