Pak. J. Weed Sci. Res. 12 (3): 235-242, 2006

STUDIES ON GA₃ AND KNO₃ IN TWO BIOTYPES OF Asphodelus tenuifolius Cav. COLLECTED FROM KARAK AND MIANWALI, PAKISTAN

Gul Hassan[1], Sana Tanveer¹ and Mohammad Munir[2]

ABSTRACT

Asphodelus tenuifolius Cav. (onion weed) is a notorious weed of sandy soils and observed as a serious weed of Rabi crops including chickpea, wheat, rapeseed and mustard. Dormancy is an overwhelming success attribute in onion weed. Weed seed dormancy is regulated by complex interaction of environmental, edaphic, physiological and genetic factors. Lab. studies were initiated in Weed Science Department, NWFP Agricultural University, Peshawar Pakistan during 2005 to investigate the response of Asphodelus tenuifolius to dormancy breaking chemicals: GA₃ and KNO₃ at 0 to 800ppm under room temperature. There were 3 runs of experiments viz. September 27, October 19 and November 1, 2005. Experiment was laid out in completely randomized design replicated twice. Each treatment comprised of a single petri dish planted with 20 seeds. The germinated seeds were subsequently converted to percentage. The germination percentage was subjected to ANOVA and means were separated by LSD test. The data revealed that the runs were extremely different from one another. Only 28% germination was recorded in the first run as compared to 91% and 86% in the second and the third run, respectively. The biotype Karak germinated slightly more (70%) as compared to the Mianwali biotype collected from Punjab. The biotype Mianwali biotype reached a climax of its germination in the second run, while Karak biotype had 100% germination in the November 1 run. The biotype x chemical x run interaction showed the highest germination in Karak treated with GA₃ during the first run, but the response of the biotype Mianwali was differential. It is concluded from our data that GA₃ was more potent in inducing germination of both biotypes and the seeds received germination signals, as the season advanced towards winter.

Key words: Dormancy, onion weed, sandy soils, Northwest Frontier Province, Punjab, competition.

INTRODUCTION

            Onion weed, Asphodelus tenuifolius Cav. (Asphodelaceae) is the worst weed of sandy soils reproducing only by aerial bulblets and has been observed as a serious weed of rabi crops including chickpea, wheat, rapeseed, mustard and canola. Dormancy introduces a temporal delay in the germination process that provides additional time for seed dispersal over greater geographical distances. Weed seed dormancy and germination are regulated by a complex interaction of environmental, edaphic, physiological, and genetic factors (Radosevich et al., 1996). Seeds that are released from the plant in a dormant state are said to exhibit primary dormancy while seeds that are released from the plant in a non-dormant state but which become dormant if the conditions for germination are unfavorable exhibit secondary dormancy. In order to break dormancy we come across two types of seed dormancy, coat-imposed dormancy and post harvest dormancy. Many seeds lose their dormancy when their moisture content is reduced to a certain level by drying (after ripening).Chilling seeds to break their dormancy is a time-honored practice in horticulture and forestry referred to as stratification. Many plants having very small seeds require exposure to light to overcome physiological dormancy.  Seed of this type must be on or near the soil surface in order to germinate. Seed dormancy can result from lack of gibberellins or cytokinin in a seed as well as from an excess of an inhibitor hormone. Embryo dormancy is thought to be due to the presence of inhibitors, especially ABA, as well as the absence of growth promoters, such as GA (gibberellic acid). The loss of embryo dormancy is often associated with a sharp drop in the ratio of ABA to GA.

Dhindwal et al. (1989) conducted field trial to check efficiency of pre- and post-em. herbicides for control of C. album, A. tenuifolius, C. arvensis and P. minor in wheat. Sharma and Singh (1989) reported that C. rotundus, A. tenuifolius, C. album and A. arvensis were the predominant weeds of wheat comprising 68.52% of the total weed population. Ruiz et al. (1990) confirmed that A. tenuifolius was genetically less variable than A. fistulosus (2n = 28 in both species). Diaz and Lifante (1991) evaluated the morphological, palynological and karyological characters of A. fistulosus, A. tenuifolius and A. cirerae. Sahai and Bhan (1991a) examined A. tenuifolius seeds germination in laboratory experiments showing maximum germination at 15°C and most rapid germination at 20°C. They also deciphered the effect of environmental conditions on the growth and reproduction of A. tenuifolius in screen-house trials (Sahai and Bhan, 1991b). Tomar and Namdeo (1991) conducted Field trials on sandy loam soil in the Rabi seasons to evaluate 7 methods of control against mainly A. tenuifolius, Chenopodium sp. and C. arvensis in mustard. Poonia and Gupta (1993) conducted field trials in which onion weed was identified as S.sclerotiorum. Malik et al. (1994) conducted a survey of the weed flora in the major chickpea and raya, C. album, A. tenuifolius, E. dracunculoides and T. polycera were the dominant weeds of both crops. Diaz and Vades (1995) studied the reproductive biology and hybridization in A. fistulosus, A. tenuifolius and A. ayardii. A. fistulosus and A. tenuifolius were autogamous plants resulting from controlled self pollination while A. tenuifolius and A. ayardii forming no fruit. Diaz and Aquinalde (1996) applied RAPD analysis on A.tenuifolius and showed the highest interpopulation variability. Patterson (1996) evaluated environmental factors that affect the growth and development of onion weed in different crops. Ishwar et al. (2000) conducted a field experiment to identify suitable herbicides for the management of onion weed in Indian mustard. Caudra et al. (1996) reported increased germination in GA₃ incubated seeds. Dormant seed of A.fatua lacked the ability to synthesize or release gibberellin in amounts sufficient to allow germination when imbibed in water (Simpson, 1965). The exogenous application of GA₃ breaks dormancy (Naylor and Simpson, 1961). Ninnemann et al. (1964) show that nitrites or nitrite-induced germination is inhibited by CCC, an inhibitor of gibberellin biosynthesis. Adkins et al., 1986 exhibit the differences between the pure lines exist in their sensitivity to GA₃ after induction of secondary dormancy determined by both genotype and the duration of after-ripening.

Keeping in view the importance of occurrence of dormancy in onion weeds, an experiment was undertaken to investigate the behavior of different dormancy breaking chemicals under the ambient conditions in the laboratory in the Department of Weed Science, NWFP Agricultural University, Peshawar, Pakistan.

MATERIALS AND METHODS

The seeds of onion weed (Asphodelus tenuifolius Cav.) were collected from different locations in Pakistan viz. Sara Kewa district Karak and Pai Khel district Mianwali, Pakistan, during April 2005 from the chickpea based cropping areas. The experiment was undertaken under the controlled environment by subjecting the seeds to different temperature regimes, GA₃ and KNO₃, Laboratory studies were initiated in Weed Science Department, NWFP Agricultural University Peshawar, Pakistan during 2005 to investigate the response of onion weed (Asphodelus tenuifoilius) seeds to GA₃ and KNO₃, at 0 to 800 ppm exposed separately to room temperature. The experiment under laboratory condition was undertaken on 27^th Sept, 9^th Oct. and 1^st Nov. Seventy two years data shows the maximum and minimum temperatures at Peshawar during the month of September and October as 42 and 12 ^o and 38.3 and 8.3^o C, respectively. The seeds were kept in petridishes in laboratory under room temperature for 4 weeks and the data were recorded on germination. Experiment was laid out in completely randomized design. This experiment has been runned 3 times and replicated 2 times, comprised of a single petri dish planted with 20 seeds. The germinated seeds were subsequently converted to percentage germination data. The germination percentage data were subjected to ANOVA technique and the means were separated by LSD test (Steel and Torrie, 1980).

RESULTS AND DISCUSSION

Investigations were undertaken at the Department of Weed Science, NWFP Agricultural University, Peshawar, Pakistan on dormancy breaking chemicals GA₃ and KNO₃ for breaking the dormancy of onion weeds, Asphodelus tenuifolius seeds. The ANOVA revealed that the differences were significant (P≤0.05) for chemicals x concentrations, biotypes x concentrations, chemicals x runs, biotypes x runs, biotypes x chemicals and biotypes x chemicals x runs. Although, non-significant statistically, for the dormancy breaking chemical concentrations, the highest germination was recorded in untreated check (72.08%) and it was closely followed by 200ppm (71.45%). While, the lowest germination was recorded in 800ppm (65.16%) [Table-1]. Among the chemicals, statistically higher germination (72.0%) was recorded in GA₃ as compared to 64.0% germination as observed in KNO₃. For the interaction of chemicals x concentrations, the highest germination was recorded in the untreated check under GA₃ application (83.33%). It was however, statistically equal to 200 and 400ppm of GA₃ (Table-1). For the chemical x concentration interaction, the lowest germination was recorded in GA₃ applied at 800ppm, which however was statistically comparable with 600ppm under the same chemical (67.92%) and all the interactions involving KNO₃ (Table-1).

   Table-1. Chemical x rates interaction for inducing germination in A. tenuifolius

Analysis of variance of the data showed that concentration x run, had significant effects on germination (Table-2). Among concentrations, although non-significant statistically, the highest germination 72.0 and 71.0% was recorded at 0 and 200 ppm respectively, while the lowest germination 64.0 and 65% as recorded at 600 ppm and 800 ppm, respectively. Whereas, among the runs, the highest germination (91%) was recorded in seeds of onion weed planted on 9th October while the lowest germination was recorded in the September experiment (Table-2).

Table-2. Rates x Runs interaction for inducing germination in A. tenuifolius.

Statistical analysis of the data showed that biotypes x concentration interaction had a non-significant effect on the germination (Table-3). Among biotypes, higher germination (70.0%) was recorded in seeds collected from Karak while the lower (66.0%) germination was recorded in Mianwali. For the interaction of biotypes x concentrations, the highest germination (75%) and (73.33%) was recorded in Karak biotype at 800 ppm and 200 ppm. Closer readings were recorded for most of the interactions involving either genotype.

Table-3. Biotypes x Rates interaction for inducing germination in A. tenuifolius.

The statistical analysis of the data further reveals that chemical x run had significant effect on the germination (Table-4). Among the chemical higher value (72.0) was recorded for GA₃ while lower germination (64.0) was observed for KNO_3. Among the runs, the higher germination (91.0) was recorded in the 2^nd run however it was statistically at par with the 3^rd run (86%) that was tried in the month of November. Among interaction of chemical x runs, the highest germination (96.75) was observed in GA₃ treated seeds in 2^nd while the lowest value (18.75) was observed for KNO₃ in the 1^st run that was seeded in the month of September (Table-4). 

Table-4. Chemical x Runs interaction for inducing germination in A. tenuifolius.

Analysis of variance of the data showed that biotypes x chemical interaction had non-significant effect on germination (Table-5). Among the interactions, the highest value (75.33%) was recorded in Karak biotype treated with GA₃ while lowest germination (62.82%) was also observed in same biotype subjected to KNO₃.

  Table-5. Biotypes x Chemical interaction for inducing germination of A. tenuifolius.

The data for the 3-way interaction of biotypes x chemicals x concentrations had a significant effect on germination (Table-6). Among the interactions, the highest germination (84.17%) was recorded in Karak biotype treated with GA₃ at 0 ppm however; it was statistically at par with the rest of the concentrations in the same chemical. While in Mianwali biotype, the highest germination (82.50 %) each was recorded in the Mianwali and Karak biotypes treated 800 ppm and 200 ppm GA₃, respectively (Table-6).

Table-6. Biotypes x Chemicals x Rates interaction for inducing germination in A. tenuifolius.

The data in Table-7 exhibit the interaction of biotypes x runs x concentrations. The differences however were non-significant statistically. The data show that the lowest germination% (11.25) was found in Karak in Sep.1 Run treated either with 400 or 600 ppm. While, the highest germination% (100 each) was also found in Karak in Nov.1 Run across all the concentrations. The Mianwali biotype performed well at the intermediate rates, however (Table-7).

Table-7. Three–way interaction of Biotypes x Runs x Rates interaction for inducing germination in A. tenuifolius.

In Table-8 the interaction of chemicals x runs x concentrations show that the lowest germination% was found in KNO₃ treated with 800 ppm(1.25%) at Sep. 1 Run, while the highest germination% (100%) was found in GA₃ at in Oct. 9 Run treated with 200 and 400ppm (Table-8). The KNO₃ during first run across all the concentrations performed the poorest.

Table-8 Three–way interaction of chemical x runs x rates interaction for inducing germination in A. tenuifolius.

The data in Table-9 manifest the three-way interaction of runs x chemicals x biotypes show following results. The lowest germination% was found in Karak in Run-1 treated with KNO₃ (16.00%) while, the highest germination% was also found in Karak at Run-3 treated with GA₃ and KNO₃ (100.0%). The differences however were non-significant statistically.

Table-9. Three–way interaction of Biotypes x Runs x Chemicals interaction for inducing germination in A. tenuifolius.

The perusal of data in Table-10 exhibits the interaction of biotypes with the runs. The germination of both the biotypes increased as the season advanced. Karak germination was about 5 times higher in Nov. 1 run as compared to September 27 run. Whereas the Mianwali biotype started with the 34% in September 29 and reached a peak in the second run and then declined to 70.5% in Nov.1. The behavior of the two types seems to be different the different runs of experiments.

The data presented above are in a great analogy with the previous work of Hassan and Khan (2005), Hassan and Khan (2004a&b) and Hassan et al. (2004c).

Table-10. Biotypes x Runs interaction for inducing germination in A. tenuifolius.

ACKNOWLEDGEMENT

The financial help of the Pakistan Science Foundation, Islamabad, Pakistan in the conduct of this research is highly appreciated.

REFERENCES CITED

Adkins, S.W. and J.D.Ross. 1981. Studies in wild oat seed dormancy I. the role of GA₃ and ethylene in dormancy breakage and germination of wild oat seeds (Avena fatua L.) Plant Physiol. 67:358-362.

Adkins, S.W., J.M. Naylor, and G.M.Simpson. 1984. The Physiological basis of seed dormancy in Avena fatua. V. Action of ethanol, GA₃ and other organic compounds. Physiol. Plantarum 62:18-24.

Caudra, C.Dela, R. Millares, De Imperial, R. Calvo, I. Walter and M. Bigeriego. 1996. Effect of stubble burning on dormancy of Avena sterilis ssp.Ludoviciana (Durr) Nyman. Boletin de Sanidad Vegetal, Plagas 22(3):613-620.

Dhindwal, A.S., K.L.Chhabra and S.P.B.Lather. 1989. Efficacy of herbicides for weed control in wheat and their residual effect on succeeding cotton crop. Pestology 13(2): 16-22.

Diaz, L.Z and B.Valdes. 1995. Reproductive biology and hybridization of the species of Asphodelus sect. Verinea (Pomel) Baker (Asphodelaceae). Botanica Helvetica 105(1): 97-109.

Diaz, L.Z and I.Aguinagalde. 1996. The use of random amplified polymorphic DNA (RAPD) markers for the study of taxonomical relationships among species of Asphodelus sect. Verinea (Asphodelaceae). Am. J.Bot. 83(7): 949-953.

Diaz, L.Z and Z.D.Lifante. 1991. Asphodelus cirerae, a forgotten species of Asphodelus sect. Verinea (Liliaceae). Morphological, palynological, karyological and ecogeographical characterization. Flora Mediterranea 1: 87-109.

Ishwar, S., H.S.Dungarwal and I.Signh. 2000. Management of onion weed (Asphodelus tenuipholius) in irrigated mustard. Indian J.Agric.Sci. 70 (11):799-800.

Malik, R.K., S.Samunder and S.Singh. 1994. Weed flora in gram and raya crops in Haryana state. Haryana Agric.Univ.J.Res. 24 (1): 7-14.

Naylor, J.M. and G.M.Simpson. 1961. Dormancy studies in seed of Avena fatua. 2. A gibberellin-sensitive inhibitory mechanism in the embryo.-Can.J.Bot.39:281-295.

Ninnemann, H., J.A.D.Zeevaart, H. Kende, and A. Lang. 1964. The plant growth retardant CCC as inhibitor of gibberellin biosynthesis in Fusarium moniliforme. Planta 61:229-235.

Patterson, D.T. 1996. Temperature and photoperiod effects on onion weed (Asphodelus tenuifolius) and its potential range in the United States. Weed.Tech.10 (4): 684-688.

Poonia, B.L and O.P.Gupta. 1993. Evaluation of herbicides in chickpea (Cicer arietinum L.) grown with or without applied phosphate under two irrigation regimes. Integrated weed management for sustainable agriculture. Proc. Indian Society of Weed Science Intl’. Symp., Hisar, India, 18-20 November 1993, Vol. III, pp.147-149.

Radosevich, S.R., J.S.Holt and C.M.Ghersa. 1996. Weed Ecology Implications for Management. 2^nd ed. John Wiley, New York.

Rathore, R.S., T.S.Rajpurohit., S.J.Solanki and H.R.Bishnoi 1993. Onion weed-a new record of Sclerotinia sclerotiorum. Indian Phytopath. 46 (3): 261-262.

Ruiz, R.C., G.Blanca. M.Cueto., R.Lozano and M.R.Ruiz. 1990. Asphodelus tenuifolius and A. fistulosus (Liliaceae) are morphologically, genetically and biologically different species. Plant Systematics Evol.169 (1-2):1-12.

Sahai, B. and M.V.Bhan. 1991a. Growth and reproduction of onion weed (Asphodelus tenuifolius) as influenced by planting time. Indian J. Agron.36 (Supplement): 194-197.

Sahai, B and V.M.Bhan. 1991b. Germination of onion weed (Asphodelus tenuifolius) as influenced by temperature, storage condition and seeding depth. Indian J.Agron. 36(Supplement):189-193.

Sharma, S.N and P.H.Singh. 1989. An ecological survey of wheat and rice fields - important weed flora of Varanasi district. Indian J. Agron.36 (Supplement):189-193.

Simpson, G.M. 1965. Dormancy studies in seed of Avena fatua 4. The role of gibberellin in embryo dormancy. Can. J. Bot. 43: 793-816.

Steel, R.G.D. and J.H.Torrie. 1980. Principles and procedures of statistics-a biological approach. 2^nd ed. McGraw Hill Book. Co., New York.

Tomar, S.S and N.K.Namdeo. 1991. Studies on chemical weed control in mustard. Indian.J.Agron.36 (1):118-121.