Effect of intercropping, phosphorus fertilization and rhizobium inoculation on the growth and nodulation of some leguminous and cereal forages

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ISSN Print: 2151-7517, ISSN Online: 2151-7525, doi:10.5251/abjna.2011.2.1.109.124

Effect of intercropping, phosphorus fertilization and rhizobium inoculation on the growth and nodulation of some leguminous and cereal forages

Awad O. Abusuwar

¹

and Eltahir A. Omer

²

1

Dept. of Arid land Agriculture, King A/Aziz University, Jeddah, Saudi Arabia E-mail: [email protected]

2

Faculty of Natural Resources, University of Upper Nile, Malakal, Sudan

ABSTRACT

A field experiment was carried out for two consecutive seasons (2005/2006 and 2006/2007) in the Demonstration Farm of the Faculty of Agriculture at Shambat, University of Khartoum, Sudan, to study the effect of intercropping, phosphorus application and Rhizobium inoculation on the performance of some leguminous and cereal forage crops. The treatments used were pure stand, a mixture of Clitoria, lablab and Sudan grass, phosphorus fertilizer and Rhizobium inoculation. They were laid out in a completely randomized block design with three replications.

Growth attributes, number of nodules, weight of nodules and prussic acid (HCN) were measured.

Results showed that stem thickness was significantly affected by intercropping and addition of phosphorus. Sole crops produced forage with thicker stems during the growth of the first crop, while intercropped plants treated with phosphorus developed thicker stems during the second cut (ratoon). The plant cover was significantly higher for Clitoria than the other species.

Intercropping and addition of phosphorus increased plant height of Sudan grass. The leaf area of Clitoria was increased with the addition of phosphorus and intercropping in the first crop, but sole Clitoria scored higher leaf area during the second cut. Lablab leaf area was significantly increased with addition of phosphorus and intercropping in the two seasons. Intercropping of Sudan grass with lablab and Clitoria resulted in large leaf area of Sudan grass. Leaf to stem ratio of Clitoria was mainly increased with the addition of phosphorus. Intercropping lablab with Clitoria significantly increased lablab leaf to stem ratio. The two-combination intercropping of Sudan grass increased its leaf to stem ratio. Rhizobium inoculation, legume to legume intercropping and addition of phosphorus enhanced nodulation and increased the number and weight of nodules. Phosphorus significantly reduced the amount of HCN in the forage of Sudan grass.

Keywords: intercropping, bio-fertilization, grass-legume mixture, phosphorus fertilization INTRODUCTION

Sustaining bio-diversity in nature is very crucial, simply because of human intervention through the process of isolating certain plants from their communities, which affects the natural distribution of plants in nature. Intercropping is the growing of two or more crops on the same land and at the same time. It is one of the methods used to return plant configuration to its natural diversity.

Bio-fertilization is the use of organic matter or microbiological inoculation to increase soil fertility.

Rhizobium plays an important role in agriculture by inducing nitrogen fixing nodules on the roots of legumes. Nitrogen fixation is one of most important biological processes on earth (Graham, 2008) and Rhizobium inoculation of legumes is one of the success stories of world agriculture (Herridge, 2008).

The process of nitrogen fixation is much cost energetically. Addition of nitrogen through the process of nitrogen fixation is cheap to the farmer, without any hazards, avoiding the use of chemical fertilizer. Intercropping of non-legume and leguminous crops probably reduce competition for nitrogen . Lablab bean is a very excellent nitrogen fixer, it is used for human consumption, cover crop and for animal feeding. Clitoria combines well with Sudan grass and some other crops, beside its palatability and nutritional value for animal. The peculiarity of the family Fabaceae is the production of bacterial nodules. Roots of leguminous plant infected by bacteria of the genus Rhizobium form nodules that vary in number and size.

Sorghum sudanense a non-leguminous crop that needs large amounts of nitrogen from the soil. The presence of Clitoria and hyacinth bean in the

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intercropping system with Sudan grass will help the availability of nitrogen through the process of N- fixation (nodules). The success of this process depends on the amount and activity of the bacteria in the soil.

Sudan grass like many other members of the family Poaceae, (Johnson grass and Sorghum) contains cynogenic glycoside, which produces prussic acid (poisonous substance to animals) (Abusuwar, 2005).

Prussic acid (HCN) inhibits oxygen utilization by the cells in the animal body, cattle and sheep (ruminant) are more susceptible. The addition of phosphorus reduces the amount of this substance in the plant tissues, and increases the resistance to plant lodging.

Phosphorus is the component of the genetic materials (DNA and RNA) and an essential element in all living cells.

Therefore, the main objective of this study was to explore the possibility of providing green forage from an intercropping system of leguminous and non- leguminous crops with high productivity and high nutritional value. The specific objectives were to: a- study the effect of phosphorus fertilization and Rhizobium inoculation on the growth and yield of cereal and leguminous forage crops, and b-evaluate mixed cropping versus monocropping systems.

MATERIALS AND METHODS

Experimental site description: The Demonstration Farm of the Faculty of Agriculture at Shambat (latitude 15°40'N and longitude 32°32'E and altitude 280 m above sea level) has a semi-desert climate with annual precipitation between 100 and 200 mm.

and a temperature ranges from 12^oC to 42^oC.

(Shambat Meteorological Station,2008).

Land preparation:

Four operations were carried out; ploughing, harrowing, leveling, and ridging 70 cm apart. The size of the plot was 3 x 5 m with six ridges. The experimental plots were protected with a guard area planted with Sorghum.

Treatments

Treatments used were:

1- Sorghum sudanense (pure stand) 2- Clitoria ternatea (pure stand) 3- Lablab purpureus (pure stand)

4- Sorghum sudanense: Clitoria ternatea 5- Sorghum sudanense: Lablab purpureus 6- Sorghum sudanense: Lablab purpureus :

Clitoria ternatea

7- Sorghum sudanense + Phosphorous 8- Clitoria ternatea + Phosphorous 9- Lablab purpureus + Phosphorous

10- Sorghum sudanense: Lablab purpureus : Clitoria ternatea + Phosphorous

11- Sorghum sudanense: Lablab purpureus : Clitoria ternatea + Phosphorous + Rhizobium

12- Clitoria ternatea + Rhizobium 13- Lablab purpureus + Rhizobium 14- Clitoria ternatea : Lablab purpureus

15- Clitoria ternatea: Lablab purpureus+

Phosphorous

Rhizobium

Phosphorous+ Rhizobium

18- Sorghum sudanense: Clitoria ternatea+

Phosphorous

19- Sorghum sudanense : Clitoria ternatea+

Rhizobium

20- Sorghum sudanense: Clitoria ternatea+

Rhizobium + Phosphorous

21- Clitoria ternatea + Rhizobium+ Phosphorous 22- Lablab purpureus + Rhizobium+

Phosphorous

23- Sorghum sudanense: Lablab purpureus : Clitoria ternatea+ Rhizobium

24- Sorghum sudanense : Lablab purpureus+

Phosphorous

25- Sorghum sudanense : Lablab purpureus+

Phosphorous+ Rhizobium

26- Sorghum sudanense : Lablab purpureus + Rhizobium

Treatments were replicated three times and the number of experimental plots were equal to 78 using a Randomized Complete Block Design.

Inoculation: The leguminous seeds were inoculated before planting with their Rhizobium strains in form of black powder, brought from the National Research Center and USDA3398 for Lablab and USDA3384 for Clitoria

Phosphorous addition: Phosphorous was added in the form of triple supper phosphate at a rate of 50 kg per hectare before planting.

Seed rate: For sorghum, Clitoria and lablab, seeding rates applied were, 10, 15, 20 kg/feddan, respectively. In case of mixture, the seed rate was half or third of that of the sole crop (half incase of two mixtures and third incase of three mixtures).

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Sowing date: The first and the second season experiments were planted at the first week of March 2005 and 2006.The first ratoons started after harvesting.

Method of planting: Seeds of legumes were drilled into the shoulders of the ridges, alternated with Sorghum seeds, row intercropping (1: 1)

Irrigation: The experiment was irrigated immediately after planting to avoid death of bacteria ( Rhizobium ) and weekly thereafter.

Weed control: The most common weeds were Buda (Striga hermonthica), Nageela (Cynadon dactylon) and Saeda (Cyprus rotundus). Weeding was carried out once after three weeks from planting. White fly was the most common insect infested lablab plants, but did not reach threshold level.

Parameters measured: Five tagged plants for each crop in the plot were taken at random from the middle rows to measure growth parameters.

Stem diameter: It was taken from the second internodes at the base of the plant after 15 days from planting and one month thereafter using a Vernia.

Leaf area: For sorghum plant, leaf number four from the top was used to determine the leaf area by leaf area meter. For leguminous plants, a fully grown compound leaf was chosen randomly to measure the leaf area, at one month interval.

Leaf-to-stem ratio: The weight of removed leaves of five randomly selected plants was divided by the weight of their stems at one month interval.

Number and weight of nodules: Three plants were uprooted for recording nodulation. Nodules were removed from roots of legumes, counted; fresh and dry weights were determined. This was done twice;

six weeks from planting and at harvest.

Prussic acid: This parameter was taken at the time of harvest, for the main crop and the ratoon. Five Sorghum plants were taken randomly, milled using pressure machine; the extracted juice was collected, filtered and centrifuged. The Spectrophotometer was used to determine the absorption of juice at wave length (λ) =293 nm, glycoside concentration was calculated according to the formula described by British Pharmacopoeia (1980).

HCN content = glycoside concentration  1.03  1000 /10.5

Data analysis: Randomized Complete Block Design was used, in which the main 26 treatments were further fractionated to obtain 16 ,16, and 12 treatments consisted of Clitoria, Lablab and Sorghum, respectively and each crop was statistically analyzed separately

RESULTS

Stem diameter (cm)

Clitoria ternatea: Clitoria thickness was significantly different with treatments in all readings except the first reading of the two seasons (Tables 1a and 1b).

Stem diameter increased with plant age. In the second readings it was significantly affected by treatments and sole Clitoria treated with P gave the thickest stems among the treatments of the second reading of the two seasons (0.38cm for the first season and 0.57cm for the second season).

At time of harvest in the first season, Clitoria (CL) treated with phosphorus (P) and Rhizobium ( R) resulted in thicker plants (0.51 cm), whereas CL/P/R treatment gave the thickest stem in the second season (0.78cm). Addition of P and R relatively increased plant thickness.

Ratoon plant was thicker than the first cut. First season ratoon gave plant with stem diameters ranged between 0.61 and 1 cm, whereas second season ratoon ranged between 0.48 and 0.92 cm.

Lablab purpureus: Stem diameter in the first and second reading of the first season did not respond significantly to the treatments, even though sole lablab developed thicker stem in the first reading and CL/P/R in the second reading.

Treatments in the first reading of the second season revealed significant difference for stem diameter (SD), in which LC/R treated plants were significantly thicker than non-treated plants (1.38cm). Planting lablab with Sorghum and Clitoria gave relatively thinner stems. At the time of harvest of the first cut lablab grown alone and lablab treated with P and R yielded thicker stems (1and 0.95cm, respectively).

Last reading of the second season showed that L/P/R treatment had the thicker stems (1.37cm) and generally sole lablab obtained thicker stems.

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Table 1.a. Effect of intercropping, phosphorus and inoculation on stem diameter (cm) of Clitoria, lablab and sorghum (2005)

Sorghum Lablab

Clitoria

At 2^nd harvest At 1^st

harvest 2^nd

reading 1^st

reading At 2^nd

harvest At 1^st

harvest 2^nd

reading 1^st

harvest 2^nd

reading 1^st

reading Treatment

1.31ab 0.95a

0.68a 0.367s

L /P/ R

0.57bcde 0.48a

0.54abc 0.18a

0.53e 0.88

0.55a 0.367a

1a 0.42ab

0.28abc 0.16a

SCL

0.56bcde 0.47a

0.42c 0.16a

0.69def 0.493ab

0.31abc 0.17a

SC/P/R

0.69bcd 0.46a

0.5abc 0.22a

1bcd 0.76abcd

0.65a 0.31a

SL

0.60bcde 0.38a

0.42c 0.31a

1.32ab 0.64cd

052a 0.367a

SL /R

0.76ab 0.55a

0.53abc 0.20a

1.28abc 0.753abcd

0.60a 0.363

SL/P

0.56bcde 0.55a

0.67a 0.21a

0.93bcde 072abcde

0.61a 0.357a

SL/P/R

0.997bcde 1a

0.69a 0.39a

L

1.5a 0.71bcd

0.69a 0.38

L/P

0.71bc 0.36a

0.36ab 0.27a

S

0.55bcde 0.39a

0.48abc 0.38a

0.87de 0.71bcd

0.51a 0.57a

0.686def 0.35

0.27abc 0.010a

SCL/P/R

1.46a 0.62cd

0.637a 0.33a

L/R

0.51cde 0.48a

0.65a 0.27a

0.867de 0.83abc

0.64a 38.a

0.72cdef 0.46ab

0.31abc 0.20a

SCL/R

0.54cde 0.50a

0.5abc 0.25

0.9cde 0.75abcde

0.60a 0.38a

0.77bcdef 0.46ab

0.7abc 0.167a

SCL/P

0.77bcdef 0.44ab

0.8a 0.203

C/P

0.87abc 0.51a

0.28abc 0.11a

C/P/R

0.49de 0.48a

0.54abc 0.19a

0.80bcde 0.39ab

0.28abc 0.16a

SC

0.47e 0.38a

0.38c 0.29a

0.64ef 0.39ab

0.37ab 167a

SC/R

0.39e 0.40a

0.41c 0.25a

0.61f 0.46ab

0.29abc 0.19a

SC/P

0.91a 0.44a

0.43bc 0.22a

S/P

0.90ab 0.47ab

0.29abc 0.18a

C

0.75de 0.68bcd

0.72a 033a

0.85abcd 0.34b

0.26bc 0.13a

CL/P

0.80de 0.747abcd

0.633a 0.33a

0.77bcdef 0.49ab

0.31abc 0.20a

CL

0.70cdef 0.45ab

0.30abc 18.a

C/R

0.84de 0.70bcde

0.75a 0.325a

0.75bcdef 0.40ab

.0.26bc 1.10a

CL/R

0.79de 080abc

0.77a 0.375a

0.90ab 0.42ab

0.28abc 0.21a

CL/P/R

0.07 0.02

0.02 0.02

0.3 0.02

0.02 0.02

0.01 0.01

0.007 0.007

SE±

8.6 29.4

21 60.2

17.3 16.04

18.1 31.8

9.57 17.18

17.2 28.6

CV

Means with the same letter (s) within each column are not significantly different at 0.05 level using Duncan’s Multiple Range Test.

Legend: C = Clitoria, L = lablab, S = sorghum, P = phosphors, R = Rhizobium

Table 1.b. Effect of intercropping, phosphorus and inoculation on stem diameter (cm) of Clitoria, lablab and sorghum (2006)

Clitoria Treatment

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harvest 2^nd

reading 1^st

harvest 2^nd

reading 1^st

harvest 2^nd

reading 1^st

reading

1.4bdce 1.37a

1.19ab 0.37ab

L /P/ R

0.77defg 0.71ab

0.55a 0.21a

0.75ef 0.87ab

0.84bc 0.32abc

0.87ab 0.34ab

0.43 0.18

SCL

0.57defg 0.70ab

0.68a 0.20a

0.60bcde 0.47ab

0.39b 0.167a

SC/P/R

0.74cdef 0.56b

0.53a 0.10b

0.897def 0.77b

0.81bc 0.35abc

SL

1.11a 0.67

0.61a 0.11b

1.2bdef 0.9ab

0.87bc 0.25c

SL /R

1abc 0.76ab

0.52a 0.14ab

1.27fbdef 0.93ab

0.92bc 0.30abc

SL/P

0.82bcde 0.78ab

0.68 0.14ab

1.57bdc 0.99ab

0.83bc 0.28bc

SL/P/R

1.012ab

0.93bc 0.30abc

L

1.77abc 0.9ab

0.987abc 0.28bc

L/P

0.8bcdef 0.65ab

0.57a 0.15ab

S

0.51fg 0.72ab

0.66a 0.167ab

1.17bcdef 0.83ab

0.86bc 0.26c

0.67bcdef 0.53ab

0.5b 0.13a

SCL/P/R

1.8ab 0.92ab

1.11abc 0.26c

L/R

1.04ab 0.78ab

0.59a 0.167ab

1.1cdef 0.93ab

0.81c 0.31

0.92a 0.44ab

0.45b 0.14a

SCL/R

0.62defg 0.82a

0.53a 0.10b

0.83ef 0.81

0.79c 0.28bc

0.697abcd e 0.42ab

0.44b 0.2a

SCL/P

0.58def 0.57a

0.49b 0.19a

C/P

0.71abcdef 0.43a

0.40b 0.14a

C/P/R

0.52efg 0.61ab

0.52a 0.13ab

0.62cdef 0.48ab

0.43b 0.17a

SC

0.53defg 0.72ab

0.63a 0.13

0.67bcdef 0.49ab

0.44b 0.13a

SC/R

0.41g 0.61ab

0.523a 0.14ab

0.54ef 0.43ab

0.42b 0.13a

SC/P

0.82bcd 0.69ab

0.57 0.13ab

S/P

0.60dcef 0.37b

0.40b 0.167a

C

0.63f 0.78b

1.003abc 0.29abc

0.79abcd 0.53ab

0.48b 0.14a

CL/P

0.59f 0.87ab

1.01abc 0.31abc

0.73abcde 0.50ab

0.44b 0.13a

CL

0.48f 0.40ab

0.46b 0.15a

C/R

2.3a 1ab

1.34a 0.287abc

0.83sbc 0.53ab

0.537b 0.13a

CL/R

0.84ef 0.72b

1.22ab 0.38a

0.81abcd 0.36b

0.7a 0.177

CL/P/R

0.02 0.017

0.02 0.006

0.05 0.04

0.07 0.02

0.01 0.017

0.01 SE±

21.08 16.4

25.3 27.3

29.19 29.5

15.8 18.08

21.4 25.7

29.7 CV

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Ratoon plants were thicker than the first crop plants.

In the first year, lablab treated with P and R gained the thickest stems (1.5 and 1.46cm), whereas in the second year, LC/R produced the thickest stems (2.3cm). Generally, lablab grown alone developed thicker stems.

Sorghum sudanense: There were significant differences in stem diameter (SD) throughout the different samplings and harvests except for the first sampling and first harvest in year one and the second sampling of year two.. Unlike Clitoria and lablab, sole sorghum in most treatments gave thinner stems compared with intercropping. The SD of the first cut of the two seasons did not reach 1cm and in the last reading of the first year the SD ranged between 0.36 and 0.55cm, whereas first crop SD ranged between 0.56 and 0.82cm. Addition of P was observed to increase SD.

The SD of the ratoon plant was slightly thicker (0.39 to 0.91 for the first year and 0.4 to 1.11 for second year) compared with the first cut. In the first year, sorghum treated with P attained the thickest stems (0.91) and planting of three crops together resulted in thicker sorghum stem. Second year ratoon revealed that SL/R significantly scored the higher value of the SD (1.11cm).Generally, addition of P increased the SD.

Leaf area (cm²)

Clitoria ternatea: All readings were significantly different in the two seasons except the second reading of the second season. The leaf area of the Clitoria ranged between 3.43 to 55 cm² for the first season and 9.32 to 57.26 cm² for the second season (Tables 1a and 1b).

In the first reading of the first season, plants treated with phosphorus or inoculated with Rhizobium were not significantly different and even sole or intercropped treatments did not affect the size of the leaves. Second reading showed an observable increase in the leaf area, sole plants relatively scored the largest leaf area. Increase in leaf area due to addition of phosphorus was observed. Inoculation did not affect Clitoria leaf area.

At time of harvest, plant’s leaf area reached the largest size compared with the previous readings.

Clitoria: Lablab /R treatment resulted in plants with the largest leaves (55 cm²) whereas C/R had the smallest leaf area (32.27 cm²). Intercropping of three plants resulted in smaller leaves. Effect of phosphorus was not statistically significant.

The leaf area of the ratoon plant was more or less similar to that of the first cut. Sole Clitoria treatment was the best one (52.5 cm²), CLS/R gained the smallest size (29.3 cm²). Although most of intercrop treatments were statistically not significant, but there were differences among means, in which mono-crops and double crops were having largest leaf areas.

Phosphorus slightly increased the leaf area.

Second season (2006), first reading plants produced large leaves compared with the first reading of the first season. Clitoria: Lablab/P/R treatment revealed plants with the largest leaf size (25.11 cm²) and the C/P/R treatment resulted in the smallest leaf area (9.32 cm²). Intercropping, addition of phosphorus and inoculation did not significantly affect the leaf area.

Even second reading was not significantly different;

Clitoria: Lablab /P/R treatment gained the largest leaf area (54.17 cm²). Last reading showed significant difference among treatments. Clitoria treated with P and R was the best treatment (86.2 cm²) with the largest leaf area throughout the two seasons. Clitoria:

Sorghum: Lablab, CS/P/R, CL/P, CL/R, C/R and CL/P/R treatments were not significantly different.

Intercropping Clitoria plant with sorghum resulted in smaller leaf area. Addition of either P or R to the soles and intercrops did not affect leaf area.

Ratoon plants showed smaller leaf area compared with the last reading of the first crop. Clitoria grown alone (C) produced the largest leaf area (50.17 cm²).

Clitoria: Sorghum: Lablab /P/R had the smallest leaf area (24.28 cm²). Inoculation relatively increased the leaf area. Phosphorus addition had no clear effect on the leaf area.

Lablab purpureus: All readings of the two seasons were significantly different except the second and the last reading of the first season. The leaf areas of lablab plant ranged between 13.6 to 167.9 cm²for the first season and 16.76 to 235.25 cm²for the second season.

First reading of the first season revealed L/P/R had the largest leaf area (25.6 cm²) and LCS/P/R had the smallest one (13.6 cm²), the rest of the means were not significantly different. Although there were very large differences between means, there were no significant differences in the second and last readings.

Leaf area in ratoon plants was significantly affected by treatments. Clitoria: Sorghum: Lablab /P/R treatment resulted in the largest leaf area (167.9 cm²) and SL was the smallest one (45.4 cm²). Rhizobium

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inoculation and addition of phosphorus at the same time increased the leaf area in different intercropping treatments.

In second season, first reading showed significant difference among treatments. Clitoria: Lablab /R and L/P/R had the largest leaf areas (93.25 and 92.87cm² respectively) and SL treatment gave the smallest leaf area (16.76 cm²). The effect of intercropping, P and R were not significant in this reading.

Second reading revealed significant variation among treatments. The maximum leaf area resulted from L/P/R treatment (216.8 cm²) which was not significantly different from CL and CL/P/R treatments;

other treatments were not statistically different in leaf area.

At time of harvest plants produced large leaves.

Lablab grown with sorghum and treated with P resulted in the largest leaves (235.25 cm²), but this treatment was not significantly different from the rest of the treatments except, SL treatment which produced plants with the smallest leaves (124.29 cm²).

Ratoon crops were significantly variable in leaf areas due to the application of different treatments. Unlike most treatments, intercropping of the three crops (LCS) produced plants with larger leaves (206.3 cm²), whereas SL/R, L, LC/P, LC, LC/R and LC/P/R gave smaller leaves.

Sorghum sudanense: The leaf area of the plant under study ranged between 2.01 to 136.9 cm² for the first season and 14.07 to 195.35 cm² for the second season. There were significant differences among treatments in the two seasons except, second reading of the first season and first and second reading of the second season. Sorghum planted with Clitoria and sole sorghum (S) produced the largest leaves (6.56 and 6.35 cm², respectively).

In spite of the lack of significance of the second reading, there was some degree of variation between means. Sorghum intercropped with lablab and treated with P was the best treatment with respect to leaf area (75.2 cm²). There was significant difference in the last reading. Clitoria: Sorghum: Lablab /R treatment produced the largest leaf area (108 cm²) and SC/R gave the smallest leaves (60.4 cm²).

Second cut revealed significant variation among treatments. Clitoria: Sorghum: Lablab /P/R treatment scored the largest leaf area (136.9 cm²), followed by SCL/P (134.4 cm²). The planting of the three crops

together with addition of P significantly increased the leaf area of the sorghum. Sorghum grown with lablab relatively gave large leaf area compared to sorghum with Clitoria.

In the second season, first and second readings were not significant, but treatment means were highly variable. Intercropping increased the leaf area of sorghum plant in the first two readings, but phosphorus and Rhizobium had no effect. At time of harvest plots planted with two or three crops produced large leaves compared with sole crops. P and R did not increase the leaf area. Second cut revealed significant difference between treatments, P relatively increased the leaf area of sorghum. In general the two combinations intercropping gave larger leaf area.

Leaf-to-stem ratio: Leaf to stem ratio decreased with the increasing of plant age in the two seasons (Tables 3a and 3b).

Clitoria ternatea : Treatments significantly affected L/S ratio in the two seasons and in all readings of the first crop except the last reading. During the first season the leaf to stem ratio ranged between 0.79 and 7.3, whereas in the second season it ranged between 1.01 and 8.8. In the first reading, generally the two-combination intercropping revealed higher ratios compared with three-combinations. The highest ratio (7.3) was obtained with sole Clitoria not treated, whereas CL/P/R was the lowest one. In most treatments, the ratio increased with the addition of phosphorus. Rhizobium inoculation did not clearly affect the ratio. Moreover, in the second reading the two crops combination and sole crops recorded the highest ratios. The effect of Rhizobium inoculation and phosphorus addition was not significantly different. Ratoon plants gave ratio between1.07 and 2.07. The SC/P/R and C/P/R treatments scored the highest value.

In the second season CL treatment gave the highest ratio in the first reading and the rest of the treatments were not significantly different. In the second reading SC treatment obtained the highest score of 2.9 and SCL/P was the lowest treatment ratio. Third reading did not show any significant difference. Ratoon of second season revealed significant difference among treatments, CL/P/R was the highest one.

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Table 2.a. Effect of intercropping, phosphorus and inoculation on leaf area (cm²) of Clitoria, lablab and sorghum (2005)

Clitoria Treatment

harvest 2^nd

reading 1^st

harvest 2^nd

reading 1^st

harvest 2^nd

reading 1^st

reading

85.7ab 142.3a

112.9a 25.6a

L /P/ R

47.9f 80.2ab

53.3a 4.38ab

101.8 143.a

122.59a 20.2ab

41.1abc 39.96ab

32.3ab 4.4ab

SCL

113.9abcd 75.1ab

36.7a 3.38ab

39.3abc 38.23ab

27.96ab 4.79ab

SC/P/R

129.4ab 62.1b

40.2a 4.6ab

45.5b 120.a

75.2a 16.2ab

SL

62.6ef 67.6ab

60.6a 3.77ab

88.02ab 63a

76.8a 16.91ab

SL /R

121.6abc 70.8ab

75.2a 4.59ab

127.3ab 130.2a

73.2a 16.97ab

SL/P

106.6abcd 96.4ab

67.7a 5.69ab

125.1ab 1375a

95.7a 23.72ab

SL/P/R

79.6ab 15.4a

107a 23.3b

L

96.6ab 100.8a

10298a 15.3b

L/P

116.4abcd 61.7b

39.6a 6.35a

S

136.9a 93.4ab

37.1a 3.28ab

167.9a 139.4a

92.35a 13.6b

48.73ab 39.6ab

20.5b 4.84ab

SCL/P/R

117.84ab 118.5

97.4a 17.64ab

L/R

82.2cdef 108a

65.5a 5.35ab

90.3ab 85.9a

102.6a 22.20ab

29.3a 47.4ab

31.87ab 4.96ab

SCL/R

134.4ab 94.4ab

49.2a 4.82ab

102.6ab 148.2a

100.97a 17.9ab

32.7bc 37.82ab

41.2a 5.8ab

SCL/P

44.97abc 38.22ab

36.6ab 4.22ab

C/P

42.6abc 4.02ab

26.5ab 3.43b

C/P/R

88.5bcdef 75.3ab

53.8a 6.56a

46.8abc 39.3ab

22.97b 4.62.ab

SC

48.3f 77.7ab

44.1a 3.3ab

47.94abc 37.7ab

21.94b 3.96ab

SC/R

72.3edf 60.4a

378a 2.01b

47.1bc 38.8ab

30.4ab 4.01ab

SC/P

79.7cdeg 61.2b

49.5a 4.93ab

S/P

52.5a 45.7ab

36.03ab 4.52ab

C

89.5ab 125.a

100.6 20.3ab

36.abc 37.1b

29.9ab 3.94ab

CL/P

142.3ab 132.a

98.1a 19.14ab

44.7abc 39.85ab

31.98ab 4.36ab

CL

41.9abc 32.27b

28.6ab 3.66b

C/R

68ab 142.9a

102.1a 19.3ab

46.9abc 55a

31.16ab 5.2ab

CL/R

118.5ab 112.2

107.7a 17.89ab

47abc 39.67ab

31.4ab 5.95ab

CL/P/R

3.7 3.4

3 0.3

6.6 6.2

4.4 0.36

1.1 1.08

1.04 0.16

SE±

25.5 28.6

44.4 42.9

43.2 35.4

30.8 22.6

17.6 18.7

23.9 23.8

CV

(9)

Table 2.b. Effect of intercropping, phosphorus and inoculation on leaf area of Clitoria, lablab and sorghum (2006)

Clitoria 1^st

reading

harvest 2^nd

reading 1^st

harvest 2^nd

reading 1^st

harvest 2^nd

reading Treatment

17.1b 199.74ab

216.87a 92.87a

L /P/ R

125.72cdef 185.48a

152.31a 47.29a

206.3a 199.16ab

143.87b 71.79abc

44.94abcd 57.25ab

46.37 22.02ab

SCL

173.17b 111.9b

141.52a 33.38a

48.78ab 58.82ab

47.7a 15.10abc

SC/P/R

143.75cd 100.87b

88.93a 14.07a

153.04c 124.29b

130.61b 16.76c

SL

134.67 97.65b

127.86a 14.88a

108.8e 172.15ab

137.84b 34.69abc

SL /R

120.64def 115.29b

118.8a 14.27a

139.05cd 235.25g

140.02b 44.75abc

SL/P

195.35a 117.19 b

121.8a 29.25a

146.53c 129.4b

108.59b 34.61abc

SL/P/R

109.11 199.36ab

121.9b 31.14

L

176.35b 185.6ab

132.55b 41.19abc

L/P

102.444gf 108.98b

121.2a 31.3a

S

135.44cd 131.46ab

136.36a 26.27a

181.11b 158.44ab

136.48b 22.14bc

43.91abcd 52.84b

49.2a 13.97abc

SCL/P/R

129.87de 190.18ab

139b 45.32abc

L/R

84.55g 122.64b

144.02s 22.93a

121.3ed 152.33ab

131.7b 69.59abc

43.91abcd 52.84a

49.59 18.62abc

SCL/R

126.59 131.42

163.98 32.53

135.37cd 179.34

180.2ab 68.57abc

34.33f 50.55b

49.59a 18.62abc

SCL/P

45b 45b

40.96a 13.3

C/P

44.45abcd 86.2a

41.96a 9.32c

C/P/R

123.77cdef 124.76b

116.05a 14.87a

41.59abcdf 49.62b

41.67a 12.54bc

SC

108.93ef 151.07ab

132.21a 19.22a

49.23b 52.2a

21.1abc SC/R

140.33 93.91b

104.07a 18.64a

39.68cdef 45.29b

40.88a 13.53abc

SC/P

145.57c 111.89b

91.42a 17.32a

S/P

50.17a 46.65b

48.07a 15.88abc

C

104.71e 155.76ab

130.87b 40.99abc

36.99ef 57.26ab

43.8a 14.10abc

CL/P

105.8 e 161.93ab

162.07ab 54.96ac

39.13 47.74b

40.06a 15.18abc

CL

41.79bdce 54.34ab

40.64a 11.93bc

C/R

112.48 201.51ab

130.77b 93.25a

42.0bcde 54.46ab

50.3a 19.91abc

CL/R

114.15e 184.74

180.4ab 88.03ab

46.91abc 54.60ab

54.17 25.11a

CL/P/R

1.92 4.66

6.2 3.39

1.58 6.76

5.5 4.91

0.56 2.43

1.3 0.87

SE±

9.29 24.8

31.7 88.8

7.86 26.5

26.2 59.51

9.3 31.5

19.5 CV 14.5

(10)

Lablab purpureus: Treatments were significantly different in the two seasons, except in the first reading of the first season. Leaf to stem ratio ranged between 0.45 and 6.7 in the first season and 0.95 to 6.9 in the second season. Although the first reading in the first season was not significant, some variations found among the means in which CL got the highest ratio. Addition of phosphorus to the plants slightly increased the ratio. The three-combination intercropped treatments gained the lesser ratios to some extent compared with soles and two intercrops.

Means were significantly different in the second reading. Lablab plants treated with phosphorus (L/P) gave the highest ratio of 3.16. Lablab: Clitoria / Rhizobium and LC/P/R were significantly lower than L/P plots. At the time of harvest L/R significantly recorded the highest ratio, whereas the LCS/P was the lowest treatment. The average leaf to stem ratio of the first season ratoon was similar to the average of the last reading. Lablab /P showed the highest ratio (2.07) and LC/R combination ranked the lowest.

In the second season, leaf to stem ratio of lablab in all readings was significantly affected by treatments.

Not like other readings, in the first reading, the intercropping of the three crops (LSC/P) gave the higher ratio, otherwise soles and two intercropped plots obtained the best results. Phosphorus addition in most cases increased the ratio.

Clitoria: Lablab /P/R revealed the higher figure (3.54) followed by LCS and LS was the lower ratio in the second reading, other treatments were not significantly different. At time of harvest lablab grown alone obtained the highest ratio of 1.74, phosphorus and Rhizobium were not clearly affecting the ratio.

Ratoon plants were significantly varied with treatments, LC/P/R (2.7) was the best treatment, addition of phosphorus and Rhizobium were not affecting the ratio.

Sorghum sudanense: First season did not reveal any significant variation, but in the second season all readings showed significant differences among treatments. Leaf to stem ratio ranged between 0.67 to 3.46 for the first season and 0.45 to 24.1 for the second season.

In the second, SC treatment gave the highest ratio of 24.1 in the first reading, the rest of the treatments were statistically not significant. In second reading, addition of phosphorus increased the ratio;

intercropping and Rhizobium did not increase the ratio. At the time of harvest SC treatment gave the highest ratio. Although, treatments were significantly

different in ratoon, the ratio was not obviously affected by inoculation and intercropping, but it was increased in most cases by addition of phosphorus.

Nodulation: This parameter was measured after 6 weeks from planting and at the time of harvest.

Clitoria ternatea

Number of nodules: In the first season, nodule counts were significantly increased (P < 0.05) with the addition of phosphorus in the first reading, in which Clitoria intercropped with sorghum gained the highest number (16.44) but at the time of harvesting nodule number were not affected by neither phosphorus nor intercropping in spite of its significant difference (Table 4).

In general, at the time of harvesting the nodule number tended to decrease. In the second reading, significant difference appeared among treatments, sole Clitoria plants obtained the highest number of nodules per plant (11.44). In the second season number of nodules per plant increased and the treatments were not significantly different in the first reading, but sole Clitoria plant got the highest number In the last reading there was significant difference among treatments. The total number of nodules decreased, the treatment (SCL/P/R) gave the highest nodulation with an average of 47.67 nodules per plant. Generally phosphorus had more effect on nodule number than Rhizobium inoculation in the same treatments.

In both seasons, the average number of nodules per plant decreased with the progresses of plant growth towards maturity. Nodules number decreased from 6.52 to 3.32 in the first season and from 34.81 to 16.53 in the second season.

Weight of nodules (gram): In the first season, weight of nodules was not significantly different between treatments in the first reading, but there were slight differences between means where the treatment (SCL/P/R) gained the heaviest weight (Table 5). In the second reading, treatments were significantly different in weight of nodules; sole Clitoria weighed the heaviest nodules with the mean of 0.6 g per nodules per plant.

In the second season nodule weight did not show any significant variation in the first reading, but at the time of harvest it revealed significant difference among treatment means. Treatment C/P/R, gained the heaviest weight. The average nodule weight per plant ranged between 0.083 to 0.158 and 0.40 to 0.74 g per plant for the first and second season, respectively.

(11)

Table 3.a. Effect of intercropping, phosphorus and inoculation on leaf to stem ratio of Clitoria, lablab and sorghum (2005)

Sorghum Lablab Clitoria At 2^nd

harvest

At 1^st harvest

2^nd reading

1^st reading

At 2^nd harvest

2^nd reading

1^st reading

At 2^nd harvest

2^nd reading

1^st reading

Treatment

1.48abcd 1.52bc 2.30ab 4.05a L /P/ R

0.87a 0.66a 1.08a 2.6a 0.77de 1.70bc 2.90ab 5.22a 1.57abcdef 1.29a 2.08ab 3.3ab SCL

1.23a 0.92 1.83a 2.33 2.07a 1.32a 2.04ab 4 SC/P/R

1.27a 0.75 0.77a 1.67a 0.70de 1.90abc 1.83ab 4.18a SL

1.23a 1.07a 1.44a 3.36 1.77abc 2.93a 2.23ab 5.83a SL /R

1.20a 0.59a 0.83a 1.53a 1.17abcde 1.72bc 2.51ab 6a SL/P

1.10a 0.57a 1.11a 1.53a 1.33 1.53bc 1.94 4.4a SL/P/R

1.7abc 1.43bc 2.25ab 5.03a L

2.07a 2.21abc 3.16a 4.5a L/P

1.23a 1.28a 1.01a 1.58a S

0.8 1.20a 1.33a 1.63a 0.63de 1.49bc 1.87 4.78a 1.83abc 1.23a 0.93b 4ab SCL/P/R

1.3ab 1.2c 2.55ab 5.11a L/R

0.67a 0.64a 1.38a 1.57a 1.03bcde 1.60bc 1.99ab 4.11 1.3cdef 1.36a 1.88ab 2.3ab SCL/R 1.10a 0.62a 1.82a 2a 0.93bcde 1.16c 2.26ab 5.8a 1.67abcde 1.097a 1.66ab 5.8ab SCL/P

1.47bcdef 1.26a 1.84ab 2.7ab C/P

0.97 0.79a .072a 1.5a 2.07a 1.046 1.77ab 3.1ab C/P/R

0.67 0.68a 1.47a 3.33a 1.23ef 1.25a 2.98a 4.5ab SC

0.9a 1.35a 1.35a 3a 1.8abcd 1.053a 1.87ab 5.8ab SC/R

1.2a 1.30a 1.41a 1.8a 1.07f 0.91a 1.75 5.3ab SC/P

S/P

2ab 1.03a 2.05ab 7.3a C

1.45bcde 1.025a 1.4ab 4.5ab CL/P

1.53abcdef 1.21a 1.97 5ab CL

1.87abc 1.46a 1.49 7ab C/R

0.45e 1.71bc 1.50b 5a 1.56abcdef 1.28a 1.75ab 5ab CL/R

1.05bcde 2.53ab 1.54b 5.5a 1.25def 0.79a 1.39ab 2b CL/P/R 0.05 0.09 0.13 0.17 0.06 0.07 0.09 0.22 0.03 0.04 0.12 0.3 SE±

32.9 63.8 65.1 51.9 33.69 28.95 30.02 30.7 14.7 26.4 40 50.6 CV Means with the same letter (s) within each column are not significantly different at 0.05 level using Duncan’s Multiple Range Test.