of rice in the vegetative stage was greater than that of soybean and field bean, ... in the light, than in rice. Thus .... as ATP into the reproductive organs (Harvey et.
Plant and Soil 155/156: 207-210, 1993 © 1993 KluwerAcademic Publishers. Printed in the Netherlands.
Comparison of production efficiency among field crops related to nitrogen nutrition and application TAKURO SHINANO, MITSURU OSAKI and TOSHIAKI TADANO
Faculty of agriculture, Hokkaido University, Sapporo, 060, Japan Key words: growth efficiency, Gramineae, Leguminosae, respiration
Abstract
It has been generally considered that the low productivity of Leguminosae is caused by accumulation in the r e p r o d u c t i v e organs of a large a m o u n t of protein and lipid, since the b i o c h e m i c a l costs of synthesizing these compounds is higher than that for carbohydrate. However, we report here on results which show that: the growth e f f i c i e n c i e s (dry matter a c c u m u l a t e d / (dry matter a c c u m u l a t e d + respiration)) of reproductive organs of Gramineae and Leguminosae were similar; the growth efficiency of rice in the vegetative stage was greater than that of soybean and field bean, regardless of nitrogen application rate; and when 14C02, ~4C-sucrose or ~4C-asparagine were introduced to the leaf at the maturation stage, respiratory loss of the introduced 14C was greater in soybean and field bean, especially in the light, than in rice. Thus, it is assumed that the low productivity in Leguminosae is caused by a larger respiratory loss under both dark and light condition in the shoot, and not in the reproductive organs.
Introduction
Materials and methods
Working from accepted biochemical pathways of synthesis, Penning de Vries et al. (1974) defined the p r o d u c t i o n c o s t o f a p a r t i c u l a r p l a n t constituent as the amount of it formed from unit weight of glucose, and on this basis ascribed values of 0.40 for synthesis of protein, 0.33 for l i p i d and 0.83 f o r c a r b o h y d r a t e . As the Leguminosae a c c u m u l a t e a large a m o u n t o f protein and lipid in their reproductive organs, respiratory losses associated with such synthesis w e r e also a s s u m e d to be h i g h e r . In a l a t e r p u b l i c a t i o n ( V e r t r e g t and P e n n i n g de Vries, 1987), the value for protein synthesis was given as 0.56 a l l o w i n g for r e d u c t i o n o f n i t r a t e by respiration at no cost in photosynthesis. In this r e p o r t , we i n v e s t i g a t e the c a r b o n e c o n o m y of m e m b e r s of the Leguminosae to e s t a b l i s h s p e c i f i c r e a s o n s f o r t h e i r low productivity in comparison with Gramineae.
Experiment 1. Winter wheat (Triticum aestivum L.) , maize (Zea mays L.) and sorghum (Sorghum bicolor Moench), rice (Oryza sativa L.), barley (Hordeum vulgare L. emend. Lam.), oat (Avena sativa L.), soybean (Glycine max Merr.), field bean (Phaseolus vulgaris L.), lupin (Lupinus albus L.), pea (Pisum sativum L.), adzuki bean (Phaseolus angularis L.), c h i c k pea (Cicer arietinum L.), peanut (Arachis hypogaea L.), p o t a t o (Solanum tuberosum L.), s u n f l o w e r (Helianthus annus L.), s a f f l o w e r (Carthumus tinctorius L.), flax (Linum usitatissimum L.), rape (Brassica napus L.), castor bean (Ricinus communis L.) and cotton (Gossypium spp.) were cultivated in a field of Hokkaido University in 1991. A m m o n i u m sulfate, superphosphate and potassium sulfate, were applied to give (g m -z) : N, 10; P, 4.44; and K, 8.3. The r e p r o d u c t i v e organs were collected every 4 to 5 days during
208 Shinano et al. m a t u r a t i o n . The r e s p i r a t o r y rate o f the reproductive organs was measured directly using a portable infrared gas analyzer for all species except potato, sunflower, safflower and castor bean . When the fruit of Leguminosae was cut from the plant the respiratory rate increased by about 2 fold within 30 s due to some w o u n d respiration effect. This effect was not observed in Gramineae. Crude lipid was extracted from a 1-g ovendried sample by 60 mL diethylether over 24h using a soxhlet apparatus. Crude protein content was estimated from the amount of nitrogen which was multiplied by 6.25. Nitrogen content was d e t e r m i n e d by K j e l d a h l ' s m e t h o d . F o r the analysis of ash, a 2-g o v e n - d r i e d sample was i g n i t e d at 5 2 5 ° C f o r 5 h, and w e i g h e d . The content of the carbohydrates was determined by subtracting the content of crude protein, lipid and ash from 100%. Experiment 2. Rice, soybean and field bean were germinated, then grown in nutrient solution. The content was N(NH4NO3) 30 mg L -1, P 2 mg t "1, K 30 mg L-', Ca 50 mgL -l, Mg 20 mg L-' and trace elements such as Fe, Mn, B, Zn, Cu, and Mo at the concentration of 2, 0.5, 0.5, 0.2, 0.01, and 0.005 mg L -1, r e s p e c t i v e l y . The pH was adjusted to 5.3. After 4 to 5 weeks preculture, each plant was transferred to a 56-L container with 5, 30 and 90 mg N L -1 treatments (5N, 30N and 90N, respectively). In the case of soybean and f i e l d b e a n , the n u t r i e n t s o l u t i o n was continuously aerated. The nutrient solution was renewed once a week. The respiratory rates of shoots and roots were measured by a differential type infrared gas analyzer. Experiment 3. Plants were g r o w n under the s a m e c o n d i t i o n s as in E x p e r i m e n t 2 u n t i l flowering. Then each plant was transplanted to a 12-L pot (one plant per pot). H a l f the plants received no nitrogen (ON) and the other halves received 60 mg N L -~ (60N). '4CO 2 was fed to rice, soybean and field bean and 14C-[U]-sucrose and 14C-[U]-asparagine to rice and soybean. The flag leaf in rice, or the fully-expanded leaf in soybean and field bean, was covered with a clear polyethylene bag, then ~4CO2 was liberated for 1 h under natural light c o n d i t i o n by m i x i n g 1 m L o f 0.18 mM N a H C O 3 with 0.37 k B q NaH14CO3 (2.06-GBq mmol -l) and 5 mL of 300
mg L-' HC104 in the bag. 14C-[U]-sucrose and asparagine was introduced through the tip of leaf. The tip of the flag leaf in rice or the fullye x p a n d e d leaf in s o y b e a n was cut by a sharp e d g e d c u t t e r in water, and then i m m e d i a t e l y soaked for 1 h under natural light condition in 50 mM sodium phosphate buffer (pH 7.5) which contained 0.37 kBq ~4C-[U]-sucrose (0.19 MBq mmol 1) or 14C-[U]-asparagine (4.78 MBq mmol4). The 14C i n t r o d u c t i o n was done f r o m 9:00 to 10:00. ~4CO2 release from the leaf was monitored for 24 h. Respired '4CO2 was aspirated, passed through mono-ethanolamine, then radioacitivity was measured with a liquid scintillation counter. When 14CO2 was introduced, 14CO2 release was m o n i t o r e d u n d e r a c o n t i n u o u s dark or l i g h t c o n d i t i o n . When 14C-[U]-sucrose or 14C-[U]asparagine was assimilated, 14CO2 was monitored under a continuous dark condition.
Results and discussion
Experiment 1. Crude chemical composition at the last sampling is shown in Table 1. The growth e f f i c i e n c y (GE) of the reproductive organs of each crop was calculated from the dry weight
Table 1. Comparison (%) of chemical components in the reproductive organs at harvest Crop
Protein
Lipid
CarbohydrateAsh
Rice Winter wheat Barley Oat Maize Sorghum Soybean Field bean Lupin Pea Adzuki bean Chick pea Peanut Potato Sunflower Safflower Flax Rape Castor bean Cotton
10.5+0.3 11.3+0.2 13.2+0.2 12.5_+0.3 10.2_+0.3 8.8+0.2 31.4+0.5 19.2-+0.7 25.1_+0.8 23.3_+0.2 21.6+0.7 17.3_+0.5 19.3_+0.5 10.1_+0.3 13.4+0.7 15.7+0.8 18.8-+0.3 20.0+0.5 19.0+0.3 13.9+0.6
2.2+0.1 82.8+0.2 1.7+0.0 82.2+0.2 3.5+0.1 81.3_+0.2 4.7_+0.1 80.3_+0.2 4.1_+0.1 84.2_+0.2 3.5_+0.1 84.9-+0.0 20.10.3 44.4+0.7 2.4_+0.1 75.5+0.7 4.1+0.1 67.4-+1.0 1.5-+0.1 72.3-+0.8 1.3+0.0 74.7_+0.3 5.1_+0.1 75.0_+0.2 30.4_+0.5 48.4_+0.4 0.1-+0.0 87.1_+0.4 41.9+1.3 41.4+1.1 16.3+0.4 65.2-+0.6 22.0-+0.3 56.4-+0.5 22.8+0.3 52.4-+0.2 37.4_+0.2 39.9+0.5 2.9_+0.0 79.8-+0.4
4.5+0.1 4.8+0.1 2.0_+0.1 2.5_+0.0 1.5+0.0 2.8_+0.0 4.1_+0.1 2.9_+0.1 3.4-+0.2 2.9_+0.1 2.4+0.0 2.6_+0.1 1.9_+0.0 2.7_+0,1 3.3+0.0 2.8+0.1 2.8_+0.1 4.8_+0.2 3.7+0.0 3.4_+0.0
Nutrient compartmentation in roots 209 Table 2. Comparison of the growth efficiency (GE) and theoretically calculated growth efficiency (GE(B)) of reproductive organ
Table 4. Amount of 14C respired by rice and soybean plants in the 24 hours following the introduction of 14C compounds to the leaf
Crop
GEa
GE(B)b Crop
Introduced compound
Light Crop condition
N i t r o g e nRespired (%)a level
Rice Winter wheat Barley Oat Maize Sorghum Soybean Field bean Lupin Pea
83.0 70.2 79.2 80.6 75.5 69.7 77.4 82.3 79.6 83.8
76.6 76.7 74.3 73.3 74.6 75.7 57.0 73.6 70.1 73.1
14CO2
Light
ON 60N ON 60N ON 60N ON 60N
8.5±2.5ab 11.0±2.5a 19.0±1.4c 20.4±0.7c 8. l±0.8a 10.4±1.4a 12.3±0.7ab 16.2±1.2bc
ON 60N ON 60N ON 60N ON 60N
10.6±2.8a 13.4±0.1 a 25.9±1.7b 32.9±2.2b 22.0±1.9a 32.5±0.4b 26.2±4.4b 33.0±8.6b
ON 60N ON 60N ON 60N
25.9±2.8a 30.2±3.3a 25.9±2.8a 30.2±3.3a 22.8_+1.8a 21.0±4.3a
GEa
Adzuki bean 82.7 Chick pea 75.9 Peanut 91.9 Potato 89.4 Sunflower 50.7 Safflower - 1 0 . 5 Flax 49.6 Rape 67.3 Castor Bean 31.7 Cotton 92.2
GE(B)b 73.8 71.5 53.4 79.0 48.9 62.8 58.3 57.5 50.0 74.7
Rice Soybean
Dark
Rice Soybean
14C-sucrose
aCalculated from cumulative averge data from 2 to 4 replictes of dry weight and respiration. bCalulated from the average values in Table 1.
Light
Rice Soybean
Dark
Rice Soybean
a c c u m u l a t e d and the r e s p i r e d a m o u n t o f substrate (CH20). The G E of each crop is listed in T a b l e 2. The l o w e s t G E was o b t a i n e d in s u n f l o w e r , castor bean and s a f f l o w e r - s p e c i e s all of high lipid content. D e s p i t e lipid contents also being high in s o y b e a n and peanut, the G E o f Leguminosae was s i m i l a r to that o f Gramineae. The G E was also c a l c u l a t e d t h e o r e t i c a l l y as G E ( B ) f r o m t h e c o m p o s i t i o n o f e a c h c h e m i c a l c o m p o n e n t by u s i n g the s y n t h e s i z i n g e f f i c i e n c y p r o p o s e d by V e r t r e g t and P e n n i n g de V r i e s ( 1 9 8 7 ) . G E ( B ) w a s g e n e r a l l y s i m i l a r to t h e e x p e r i m e n t a l l y o b t a i n e d G E in Gramineae, but was l o w e r than
Table 3. Comparison of growth efficiency (GE) and theoretically calculated growth efficiency (GE(B)) of whole plant among rice, soybean and field bean Crop
Nitrogen level
GEa
GE(B)b
Rice
5N 30N 90N 5N 30N 90N 5N 30N 90N
69.8 63.9 64.0 59.1 55.7 55.6 58.4 59.7 54.1
74.1 72.7 71.2 73.3 71.7 70.5 73.6 71.6 70.4
Soybean
Field Bean
a Calculated from cumulative average data from 2 to 4 replicats of dry weight and repirtion. b Calculated from the crude chemical component (data not shown)
14C-asparagine Dark
Rice Soybean Soybean
Respired (%) is the ratio of respirtory loss of 14C from the 14C fed leaf to the total amount of 14C assimilated by plant. b Within columns of each introduced compound different letters are significantly different at P
