Response of faba bean (Vicia faba L

Organic Farming: An Option To Reduce Environmental Degradation

RESPONSE OF FABA BEAN (VICIA FABA L.) TO OROBANCHE CRENATA INFESTATION IN RELATION TO DIFFERENT WATERING REGIMES

Magdi T.Abdelhamid1*, D.S.Darwish**, M.M.F.Abdalla**, R.R.El-Masry* * Botany Department, National Research Centre, Al-Behooth Street, Dokki, Cairo, Egypt. 1Email: [email protected] ** Agronomy Department, Faculty of Agriculture, Cairo University, Giza, Egypt

ABSTRACT – Two field experiments were carried out to investigate the effects of different watering regimes on the relationship between faba bean and Orobanche crenata and to explore the performance of some faba bean cultivars under free and infested conditions. The experiments were conducted using three watering regimes, irrigation at 20% (wet), 40% (medium) and 60% (dry) depletion of available soil moisture. Four faba bean cultivars (Giza 3, Giza 402, Assiut 104 and Cairo 241), and two infection conditions (infested and free) were used. The field experiments were conducted at the experimental farm, Faculty of Agriculture, Cairo University, Egypt. The first was carried out under an Orobanche free while the second one was conducted under the infested field. Orobanche attack depressed all studied traits. Drought and Orobanche parasitism had harmful effects on faba bean crop. The application of irrigation when depletion 40% of the available soil moisture content exhibited proper regime for obtaining reliable seed yield with suitable seed chemical constituents for faba bean production. Furthermore, this regime will reduce the infestation rate of Orobanche than wet regime when using tolerant genotypes whenever the soil is infested by Orobanche crenata. Key words: Broomrape; Faba bean; Orobanche crenata; Vicia faba L.; Watering regimes.

INTRODUCTION Broomrape (Orobanche crenata Fork.) is considered a major challenge to the cultivation of faba bean in Egypt. Orobanche crenata can cause faba bean (Vicia faba L.) yield reduction, ranging from 5 to 100%, depending on the severity of infestation (Parker and Riches, 1993). In severly infested fields the crop is wiped. The control of this parasite is more difficult because of its production of huge tiny seeds which disperse rapidly by wind and other means and remain viable for many years until germinated by secreted stimulant/s of proper host/s. Different cultural or chemical methods were suggested to control Orobanche and /or may alleviate its damage. Unfortunately, these methods produced up to now incomplete satisfactory results. Use of tolerant host stocks may also provide a reliable protection from Orobanche. Instability of reaction and production of faba bean observed among seasons and locations. This instability may be due to many factors including environmental effects. The soil moisture content is considered one of the conditions affecting the productivity of faba bean cultivars either infested or uninfested by Orobanche. Moreover, the performance of Orobanche-tolerant cultivars and their reaction to parasitism could be varied greatly due to irrigation treatment. Kasasian (1973) pointed out that the wet regime of soil moisture had much less effects on the host and the moisture content of the soil only affects the expression of symptoms occurring on faba bean due to Orobanche parasitism rather than the number of broomrapes on the host roots. Zahran (1973) found that the irrigation at either 10 or 30 day intervals resulted in reduction of Orobanche infestation in a heavily infested field and the yield of faba bean was consistent with the degree of Orobanche infestation. Schmitt et al. (1979) reported that broomrape infections in faba bean were weak and irregular in dry winter in Morocco. Mesa-Garcia et al. (1984) stated that increasing soil moisture content from the wilting point to saturation in pots increased the establishment of broomrape and final emergence of faba bean was higher. Linke and Vogt (1987) concluded that the moist conditions may lead to the higher rate of infestations. ter Borg and Van Ast (1991) reported that dry weight of host and the number of parasite were generally higher under moist than under dry conditions. The objectives of these studies are ti investigate

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the effects of some watering regimes on the relationship between faba bean and Orobanche crenata and to explore the performance of some faba bean cultivars under free and infested conditions.

MATERIALS AND METHODS Two field experiments were carried out during 1995/96 season at the Agricultural Research and Experiments Centre, Faculty of Agriculture, Cairo University, Giza, Egypt. The first was conducted under a free field while the second was carried out under an Orobanche-infested one. Randomized complete block design for irrigation treatments with faba bean cultivars as split-plot on treatments with four replication was used. Each subplot consisted of 5 ridges, each 4 m long and 60 cm apart. Seed were hand planted at mid November in 2-plant/hills, 20 cm apart on one side of the ridge. An alley (2-m) wide was left as border between irrigation treatments. Four faba bean cultivars were used in this investigation i.e., Giza 3 as Orobanche susceptible cultivar and Giza 402, Assiut 104 and Cairo 241 as tolerant ones. The faba bean cultivars were tested under three irrigation treatments: irrigation at 20, 40 and 60 % of available soil moisture depletion, tentatively considered as wet, medium and dry treatments, respectively. Soil moisture was determined at depths varied from one growth stage to another. Soil samples were taken by an Augar every 2 days to determine the soil moisture content. Orobanche-free field experiment: A ten plant samples/plot at day 120 age were used to measure different growth characters. Photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids mg/g fresh weights were extracted from representative samples of leaves at day 120 using 85% acetone. Pigments were measured by Spectrophotometer at wave length 662.0, 644.0 and 440.5 nm for chlorophyll a, chlorophyll b and carotenoids, respectively (Wettstein, 1957). At harvest a sample comprising 10 guarded faba bean plants were taken from each experimental plot to study the yield per plant. The seed yield per plot was determined from a bordered area equal to 8.4 m2 consisted of 4 ridges each 3.5 m long. Orobanche-infested field experiment: Orobanche crenata emergence dates were recorded. Data were collected at 120 days age using one ridge per plot. Photosynthetic pigments contents were measured. Due to insufficient fresh leaves in the cultivar Giza 3, photosynthetic pigments were not determined. At harvest, all plants within a bordered area of 8.4 m2 were harvested and the traits were recorded. Log (x+1) transformation was applied before the analysis of variance for data of Orobanche. Data as percentages were arc sin transformed before analysis of variance. Chemical analysis: In both experiments some chemical constituents were determined from the cotyledons of harvested seeds. Total nitrogen percentage (N%) was determined by Kjledahl method, total crude protein (T.C.P%) by N% x 6.25, total phosphorus (P%) according to Tourg and Mayer (1939), total potassium percentage (K%) by using flam spectrophotometer AA-646 with a boiling air-acetylene burner and recorded read out and total carbohydrate were determined according to Herbert et al. (1979).

RESULTS AND DISCISSION Results in Table 1 revealed that water deficit had a marked effect on studied traits. The dry weight of faba bean plant was depressed (by 19.1% in free and 28.7% in Orobanche field) by increasing the depletion percentage of available soil moisture. The differences in amount of water supply not only affected dry matter accumulation and partitioning but also seed yield. To elucidate the effects of drought on faba bean, the relative percentage of dry treatment to wet one was estimated for the studied traits. Most traits either at day 120 or at harvest were reduced by dessication treatment, except photosynthetic pigments contents. N% and protein content were not affected due to drought stress. Photosynthetic pigments were increased by decreasing the available soil moisture except chlorophyll b under Orobanche field. Drought stressed plants try to compensate the reduction in LAI by increasing the photosynthetic pigments contents in the remaining leaves. Fahmy et al. (1990) found that under low water treatments plants maximize

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their relative photosynthetic activity even during senescence. The high carotenoids contents of the plant leaves under low watering supply are more stable than the chlorophyll.

Table 1. Influence of watering regimes on faba bean studied traits and % depression due to drought under both Orobanche-free and infested trials Traits Orobanche-free field Orobanche-infested field Watering regimes Drought Watering regimes Drought Dep.% Dep.% Wet Med Dry Wet Med Dry Date of Orobanche 91.8a 89.4ab 88.3b 8.3 emergence At day 120: Plant dry weight (g) 68.7a1 51.9b 55.6b 19.1 16.4a 13.9b 11.7b 28.7 LAI 16.6a 11.3b 10.9b 34.3 24.0a 2.1a 1.9a 20.3 Chlorophyll a 0.629b 0.680ab 0.710a -12.9 0.523a 0.508a 0.532a -1.7 Chlorophyll b 0.401b 0.436ab 0.467a -16.5 0.440a 0.369b 0.360b 18.2 Carotenoids 0.132c 0.149b 0.179a -35.6 0.120b 0.164a 0.159a -32.5 Dead hosts % 30.4a 28.0a 41.2a -35.5 At harvest: Plant dry weight (g) 107.1a 102.6a 86.5a 19.2 40.4a 37.7a 23.5b 41.8 Seed yield per plant (g) 46.6ab 50.2a 39.3b 15.6 9.0ab 9.7a 5.5b 38.9 Seed yield per plot (g) 2103b 2714a 1855b 11.8 118a 118a 64.5a 45.1 No. Orobanche per plot 339a 283a 302a 10.9 Dry wt. Orobanche per 358a 289a 277a 22.6 plot 13.9a 10.1a 42.6 Podded hosts % 17.6a N% 4.34a 4.31a 4.35a -0.2 4.32a 3.93b 4.25ab 1.6 P% 0.703a 0.691ab 0.625b 11.1 0.674a 0.700a 0.539b 20.0 K% 1.013a 0.971ab 0.964b 6.6 0.998a 0.990a 0.911b 8.7 Total rude protein % 27.1a 27.0a 28.2a -0.2 27.0a 24.6b 26.6ab 1.5 Total carbohydrate % 61.1a 57.3ab 56.4b 7.8 53.2b 55.5a 56.6a -6.3 %depression of dry regime to wet one 1

Means of treatments under the same experiment followed by the same letter/s are not significantly different (P < 0.05)

Drought induced earlier Orobanche emergence coupled with less spikes and more dead hosts and drastic reduction in podded host%. Tamaki and Naka (1971); Moursi et al. (1976); Farah (1981); Dantuma and Grasnof (1984); Grashoff (1992); Khalil (1995) and other reported that dry condition limiting the vegetative growth and consequently the dry matter accumulation. This is due to that water deficit resulted in shortage of assimilates in the plant. Stress condition affects also the mobility of nutrients (Viets, 1967) due to the reduction of water translocation and nutrients in the transpiration stream. Therefore, the accumulation of nutrients in the seeds was reduced. Even though, the plant itself under stress condition suffers from decrease of nutrient uptake (Tamaki and Naka, 1971). Schroeder (1983) ascribed the depression in faba bean yield under drought condition to inability the plant to supply enough photosynthates to all competing sinks. The exposure to stress resulted in stomata closure to conserve moisture required to allow survival of plant tissues (Muchow and Sinclair, 1989; Darwish and Fahmy, 1997). Moreover, seed yield under free field was significantly reduced by either excessive or shortage of soil moisture. Excessive or shortage of water supply is an important factor determining growth and yield of faba bean. However, water deficit seemed to be the major yield limiting factor as proved by Grashoff (1992). The reduction of yield varied considerably among genotypes, therefore, testing of various genotypes to optimum watering supply and sensitive developmental stages to the unsuitable regimes need to be investigated. The estimates change % of infested-field results to corresponding ones under Orobanchefree field may be tentatively considered as a measure of the effects due to Orobanche

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parasitism (Table 2). It could be noted that Orobanche attack depressed all studied traits except chlorophyll b (under wet regime), P%, K% and caroteniods (under medium treatment), and carbohydrates % (under dry). The extent of depression percentage due to Orobanche attack for most studies traits did not change according to the watering supply. This proved the independence of both parasitism effects and the drought influences. Orobanche is parasitic weed unable to synthesis organic carbon, thus its effects on the host associated with photosynthates depletion (Whitney, 1995). The doubled stress (drought plus Orobanche may result in insufficient sources to be translocated to the sink, i.e., seeds. High soil moisture increases the potential of Table 2. The percentage of changes due to parasitism with Orobanche crenata either under different watering regimes or for studied faba bean cultivars Watering regimes (%) Cultivars (%) Wet Med Dry Giza 3 Giza Assiut Cairo 402 At day 120: Plant dry weight 76.1 73.2 79.0 79.2 81.4 69.8 74.9 LAI 85.5 31.4 82.6 90.2 87.0 70.8 84.0 Chlorophyll a 16.9 25.3 25.1 29.5 -2.0 36.1 Chlorophyll b -9.7 15.4 22.9 27.8 -6.8 14.9 Carotenoids 9.1 -10.1 11.2 19.6 5.6 -10.1 At harvest: Plant dry weight 62.3 63.3 72.8 88.1 69.4 53.5 51.1 Seed yield per plant 80.7 80.7 86.0 100 88.9 75.9 66.9 Seed yield per plot 94.4 95.6 96.5 100 98.2 94.8 88.2 N% 0.5 8.8 2.3 6.8 2.4 5.5 P% 4.1 -1.3 13.8 -9.1 14.9 -0.2 K% 1.5 -2.0 3.7 -2.5 2.1 0.3 6.7 2.5 5.5 Total crude Protein % 0.4 8.9 5.7 Total carbohydrate % 12.9 3.1 -0.4 11.1 4.4 -1.2

successful infection (Link and Vogt, 1987). This was true for the recorded Orobanche measurements in spite of insignificant differences among watering regimes. Dead hosts % and podded plants % were higher and lower under stressed conditions, respectively. Aalders and Pieters (1987) and Radwan et al. (1988) reported that the Orobanche attack to be correlated positively with the growth vigour of the host. Ter Borg and Van Ast (1991) found that number and dry weight of Orobanche crenata could be increased under wet conditions attributed to the large host root system. The relative performance of faba bean cultivars under Orobanche –infested field to free one, was varied for all studied traits (Table 2). Giza 3 (Orobanche susceptible cultivar)exhibited drastic depression due to parasitism. However, Giza 402 (a tolerant one) behaved similarly to Giza 3. The date of onset parasitism may play a role in the extent of reaction. Zaitoun et al.(1991) reported that the earlier infection with Orobanche crenata was corresponding with the susceptibility to broomrape infestation. Radwan et al.(1988) found that variation in the early count of parasite was determined by differences among the parasite sources. Whereas, differences among host genotypes were mainly responsible for variation in later count. Results of the present study showed that both Giza cultivars significantly exhibited earlier appearance of Orobanche than Assiut and Cairo ones. This May be an indicator of the earlier occurrence of infection or/and the rapid development of the parasite in both hosts( Darwish, 1982). However, Giza 402 still shows some tolerance to Orobanche as expressed in lower dead host% (33.5%) relative to those recorded in Giza 3 (51.5%). The percentage of podded host plants at harvest was nill (Giza 3) and increased from Giza 402 to Cairo 241. Darwish (1987) reported that dead hosts % was positively genetically correlated with Orobanche counts. The amount of reduction in both chlorophyll a and b by Orobanche infestation was more than those occurring in carotenoids. The rate of leaf senescence under both infestation and drought was higher than under drought alone as evident for more carotenoids in both stresses.

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To illustrate the variation in photosynthetic pigments due to both stresses, the following table presents these reactions. Criteria Orobanche-free field Orobanche-infested field Wet Med Dry Wet Med Dry Chlorophyll a + b 1.03 1.12 1.18 0.963 0.877 0.892 Chlorophyll a / b 1.60 1.60 1.52 1.190 1.380 1.480 (Chlorophyll a + b)/ Carotenoids 7.8 7.5 6.60 8.000 5.400 5.600

Generally, chlorophyll a+b contents were lower under Orobanche-infestation. Declining available soil moisture reduced these pigments under Orobanche attack and vice versa under Orobanche –free field. Reducing soil moisture in free-infested field lowered a/b ratio and vice versa under Orobanche-infestation. This may be attributed to more production of chlorophyll a for maximizing the relative photosynthetic activity under both stresses. Concerning a+b / carotenoids ratio, drought stress reduced it under both infested and free conditions. However, the rate of reduction was more under infestation than under free-infested conditions. This means that leaves rapidly enter into senescence due to reducing available soil moisture, whereas, this rate of senescence was increased as the stress doubled (drought + Orobanche). The accumulation of nutrients was reduced under the influence of drought condition. This accumulation was decreased by extra stress; i.e., Orobanche attack. This may be due to the depletion effects (water + nutrients + organic compounds) of Orobanche from faba bean host plants. Differences in carbohydrate % were observed between Orobanche-infested experiment and free one. The calculation of yield produced per plant for seed chemical constituents and their depression % due to both stresses presents the effects obviously as follows:

Orobanche-free field

Orobanche-infested field

Wet Med Dry R Wet N/plant (g) 2.02 2.17 1.71 15.3 0.39 P/plant (g) 0.33 0.35 0.25 24.3 0.06 K/plant (g) 0.47 0.49 0.37 21.3 0.09 Protein /plant (g) 12.64 13.53 10.68 15.5 2.43 Carbo../plant (g) 28.48 28.78 22.15 22.2 4.79 R = Reduction % due to dry relative to wet

Med 0.38 0.07 0.10 2.38 5.38

Dry 0.23 0.03 0.05 1.46 3.11

R 41.0 50.0 44.4 39.9 35.1

Depression % due to Orobanche parasitism Wet Med Dry 80.7 82.5 86.5 81.8 80.0 88.0 80.9 79.6 86.5 80.8 82.9 86.3 83.2 81.3 86.0

Calculated data proved that decreasing the available soil moisture content reduced the yield of all determined seed chemical constituents under both conditions. This reduction was doubled when the plants were parasitized by Orobanche. It could be concluded that both drought and Orobanche parasitism had harmful effects on faba bean crop. Therefore, alleviation of such effects either through cultural practices or breeding procedures is considered an important goal of faba bean specialists and other cooperated scientists. The application of irrigation when depletion 40% of available soil moisture content exhibited proper regime for obtaining reliable seed yield with suitable seed chemical constituents of faba bean production. Furthermore, this regime will reduce infestation rate of Orobanche than wetter regimes using tolerant genotypes whenever, the soil is infested with Orobanche crenata.

REFERENCES Aalders, A.J.G. and Pieters, R. (1987). Resistance in Vicia faba to Orobanche crenata: True resistance versus hidden susceptibility . Euphytica 36: 227-236.

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Radwan, M.S.; Abdalla, M.M.F.; Fischbeck, G.; Metwally, A.A. and Darwish, D.S. (1988). Variation in reaction of faba bean lines to different accessions of Orobanche crenata Forsk. Plant Breeding 101: 208-216. Scmitt, U. ; Schulter, K. and Boorsma, P.A. (1979). Control quimico de Orobanche crenata in Vicia faba. Boletin Fitosanitrio FAO 27: 88-91. Schroeder, P. (1983). Influence of drought stress on nitrogen content of faba bean seed. FABIS Newsletter No.7: 28-30. Tamaki, K. and J. Naka (1979). Physiological studies of the growing process of broad bean plants. III. Effects of soil moisture on the growth and the variations of chemical components in the various organs. Technical Bulletin of Faculty of Agriculture, Kagawa University 22(50): 7382. Tourg, E. and Meyer, A. M. (1939). Improvement in dieness colorimetric method for phosphorus and arsenic. Ind. Eng. Chem. Anal. Ed. 1: 136-139. Viets, F. G. (1967). Nutrient availability in relation to soil water. In Irrigation of Agricultural lands, Agronomy11, Hagan, R.M.; Haise, H.R. and Edminster, T.W. (eds.). pp. 458-471. Wettstein, D. von.(1957). Chlorophyll-lethale und der submikroische from wechsel der plastin. Exptl. Cell. Res. 12: 427-507. Whitney, P.J.(1995), Broomrape and beans. Biologist 42: 162-164. Zahran, M.K. (1973). Control of broomrape in field and vegetative crops in Egypt. Final Technical Report, Agricultural Research Program, Public Law 480, Egypt. Zaitoun, F.M.F.; Al-Menoufi, O.A. and Weber, H. (1991). Mechanisms of tolerance and susceptibility of three Vicia faba varieties to the infection with Orobanche crenata. In Proceedings of the 5th International Symposium of Parasitic Weeds, 1991, Ransom, J.K.; Musselman, L.J. ; Worsham, A.D.and Parker, C. (eds.). Nairobi, Kenya, pp. 195-207.

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