71. Habiba Raceme Position Mustard

Effect of raceme position on reproductive efficiency of mustard genotypes Fakir, M.S.A., Habiba, U., Uddin, M.N. and Imam, M.M. Department of Crop Botany, Bangladesh Agricultural University, Mymensingh, Bangladesh, Email: fakirmsa@gmail.com fakirmsa@yahoo.com ABSTRACT In a field experiment, numbers of flower and siliqua, reproductive efficiency, and fruit and seed sizes were compared in proximmal (basal) and distal (top) end of the raceme of nine Brassica spp. Result revealed that generally, irrespective of genotypes, fewer flowers and increased number of silqua were set at proximal than in the distal end of the raceme while fruits and seeds were heavier at former than in the latter in some genotypes. In others, siliqua and seeds were of equal sizes both in proximal and distal region of the raceme. Proximal and distal position in the raceme influenced pod and seed size, and seed yield in mustard. Key words: Mustard, raceme, proximal and distal, flower & siliqua INTRODUCTION One of the most important characters of an ideotype is the magnitude of sink (flower and siliqua) production. In mustard, the rate of flowers which form siliqua is only about 45% (Tayo and Morgan, 1975). Khaton (2004) observed 63 to 80% fruit set in 20 different varieties of mustard under Mymensingh condition. Reproductive efficiency (RE) i.e. magnitude of flower production and propensity of siliqua formation determines final seed yield. Research information on reproductive efficiency (RE) is available at home and abroad (Tayo and Morgan, 1975; Ferranti et al., 1994; Khaton, 2004; and Shil, 2005; Fakir et al. 2012). Variation of % fruit production depends on genotype, location and methods of assessment (Fakir, 1997). Different reproductive efficiency methods (REMs) have been employed in peanut (Coffelt et al., 1989; Mondal et al., 2003), in tomato (Khalid, 1999) and in mustard (Islam, 2006; Islam and Fakir, 2012). In most legume crops, the earlier formed-pods are larger than the later-formed ones and contain more and/or heavier seeds (Sinha, 1977). The simplest explanation for this phenomenon is that the filling of the later-formed pods may be limited by the inadequate supply of photoassimilates and other nutrients i.e. source limiting. In such a situation seed yield may be limited by the ability of the plants to supply developing pods with nutrients, rather than by the number of pods set (sink limiting). In legumes, under normal conditions more pods are set from earlier- than from later-formed flowers, and more pods are born at the nodes towards the proximal end of the branches and of the racemes (Fakir et al., 1998; Fakir et al. 2000). The average weight of later-formed pods should therefore be less than that of the earlier-formed ones. Research showed that earlier-formed pods in the racemes are heavier than in the later-formed ones in pigeonpea (Sheldrake and Narayanan, 1979). In soybean, the seeds of later flowering were smaller than those of earlier flowering due to shortened duration of seed growth (Isobe et al., 1995). In mustard, Fakir et al. (2012) observed that reproductive efficiency (percent fruit set to flower), siliqua and seed yield decreased with the progression of nodal position from proximal towards distal position in the raceme. However, information on comparison of earlier- and later-formed fruits and seeds are scanty in mustard and needs investigation. The experiment was, therefore, carried out to examine the reproductive efficiency of proximal and distal regions in the raceme of nine genotypes of Brassica spp. MATERIALS AND METHODS Nine varieties of mustard or rapeseed, four from Bangladesh Agricultural Research Institute (BARI), Gazipur and five from Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh were collected and used in the experiment and is given below. S1. No. Variety Source Species 1. BINA sarisa 3 BINA, Mymensingh Brassica napus 2. BINA sarisa 4 BINA, Mymensingh B. napus 3. BINA sarisa 5 BINA, Mymensingh B. napus 4. Safal BINA, Mymensingh B. campestris 5. BARI sarisa 6 BARI, Gazipur B. campestris 6. BARI sarisa 7 BARI, Gazipur B. campestris 7. BARI sarisa 8 BARI, Gazipur B. campestris 8. BARI sarisa 11 BARI, Gazipur B. campestris 9. BARI sarisa 13 BARI, Gazipur B. campestris The experiment consisted of two factors, genotypes and raceme positions (proximal or basal and distal or top). Eighteen treatments (9 genotypes × 2 raceme positions) were laid out in a Randomized Complete Block Design (RCBD) with three replications. The size of unit plot was 2 m × 1 m. The plot to plot distance was 0.5m and block to block distance was 0.8m. The line to line and plant to plant distances were 20 and 10 cm, respectively. In the experiment, full dosage of fertilizers (triple super phosphate, muriate of potash, gypsum, zinc oxide and boric acid @ 25, 50, 25, 2 and 1 kg ha-1 as P, K, S, Zn and B, respectively) were applied as basal dose at the time of final land preparation. N @ 75 kg ha-1 from urea was applied in two installments; half at final land preparation and the rest was top dressed before flowering. Seeds were sown manually in continuous line on November 24, 2005. Thinning of seedlings was done in two installments during 10 and 18 days after emergence (DAE) maintaining a 10 cm distance between plants. The plots were weeded twice, 10 DAE and 18 DAE. The field was irrigated twice, first at 24 DAE and second one at 50 DAE. Excess water was allowed to drain out leaving the field around field capacity. Malathion was sprayed @ 2ml/L water to minimize aphid. The experimental plots were harvested separately when 70-80% siliqua reached maturity (straw color). Different varieties were matured at different dates. The harvested crop of each plot was bundled separately, tagged properly and brought to laboratory. Five racemes from each replication, randomly selected, were cut and separated for further study. Each raceme was cut at the centre, separating the lower portion as proximal (basal) and upper portion as distal (top). Number of reproductive unit (bud + flower + siliqua + abscised structures), number of fruit, seed weight/siliqua, pericarp weight/siliqua, siliqua and seed size were recorded separately for proximal and basal portions. All the collected data were analyzed following the analysis of variance (ANOVA) technique and mean differences were adjudged by DMRT (Duncan's Multiple Range Test) using a statistical programme, MSTAT. RESULTS Reproductive unit (RU): The interaction effect of raceme position and variety on the number of reproductive unit (RU) (bud) was significant for Brassica species (Table 1). Generally, RU was greater in distal than in the proximal position except BARI sarisa 11 where it was same in the distal and proximal position (15.0) (Table 1). The mean value of RU was greater in BARI sarisa 13 (21.33) than in the others. The RU of BINA sarisa 3, safal, BARI sarisa 8, BARI sarisa 11, BINA sarisa 4, BINA sarisa 5, BARI sarisa 7 were 19.25, 17.00, 16.25, 15.50, 15.16, 15.08, 15.00, respectively. The lowest mean value of RU was found in BARI sarisa 6 (14.50). The reproductive unit (RU) was fewer in the proximal than that in the distal end with the degree being varied between the genotypes (Table 2). For example, in BINA sarisa 3, BINA sarisa 4, Safal, BARI sarisa 6, and BARI sarisa 13, the number of RU was greater in distal region than in the proximal one (Table 2). Mature fruit: Number of mature fruit was similar between proximal and distal position. The number of mature fruit varied significantly in nine mustard genotypes (Table 1). BARI sarisa 13 produced maximum mature fruit (18.83) followed by others. BINA sarisa 3, safal, BARI sarisa 11, BARI sarisa 7, BARI sarisa 8, BINA sarisa 4 and BARI sarisa 6 produced mature fruit of 15.00, 14.33, 13.66, 13.00, 13.00, 12.33, 11.83, respectively. The lowest mean value was found in BINA sarisa 5 (11.00) (Table 1). In contrast to RU, the number of fruit was generally smaller in the distal region than in the proximal position in the raceme with the degree being varied between the genotypes (Table 1). For example, the number of fruit in BARI sarisa 13, BARI sarisa 7, BARI sarisa 6 and BINA sarisa 4 was greater in the proximal region than in the distal one whereas it was similar in the others. Table 1. Interaction effect of variety and position of raceme (proximal, P and distal, D) on flower and siliqua production in mustard genotypes Variety Raceme position Number of reproductive unit Number of mature siliqua BINA sarisa 3 P 16.0 15.0 D 22.0 15.0 BINA sarisa 4 P 13.6 13.3 D 16.6 11.3 BINA sarisa 5 P 14.6 11.3 D 15.5 10.6 Safal P 15.6 14.3 D 18.3 14.3 BARI sarisa 6 P 12.5 13.0 D 16.5 11.0 BARI sarisa 7 P 14.5 14.0 D 15.5 12.0 BARI sarisa 8 P 15.5 13.6 D 17.0 12.3 BARI sarisa 11 P 15.5 14.3 D 15.5 13.0 BARI sarisa 13 P 17.0 21.0 D 25.6 16.6 LSD 0.05 - 1.59 1.56 Reproductive unit, RU = No. of bud + No. of flower + No. of mature and immature siliqua + No. of scar. Seed weight/siliqua: The higher seed weight/siliqua was observed in the proximal (0.117 g) than in the distal (0.082 g) one (Table 3). The weight of seed/siliqua was significantly different among the cultivars of nine B. spp (Table 3). The seed weight/siliqua was observed higher in BARI sarisa 11 (0.162 g) than in the others. BARI sarisa 8, BINA sarisa 5, Safal, BINA sarisa 3, BARI sarisa 13, BARI sarisa 7 and BARI sarisa 6 produced seed weight/siliqua of 0.117, 0.112, 0.110, 0.102, 0.091, 0.083 and 0.078 g, respectively. The lowest seed weight/siliqua was observed in BINA sarisa 4 (0.040 g). The interaction effect of raceme position and variety on seed yield/siliqua was significant and the seed weight/siliqua was generally, smaller in the distal region than in the proximal one in the raceme with the degree varied between genotypes (Table 4). For example, seed weight/siliqua in BARI sarisa 11, BARI sarisa 7, BINA sarisa 3, BINA sarisa 4 and BINA sarisa 5 was smaller in the distal region than in the proximal one whereas it was similar in the others (Table 4). Siliqua size (weight/siliqua): The siliqua size or weight of the individual siliqua was higher in the proximal (13.96 g) than in the distal (13.40 g) (Table 2). In respect of variety, the siliqua weight was observed highest in BARI sarisa 11 (0.281) than in the others (Table 2). BARI sarisa 8, BINA sarisa 5, BINA sarisa 3, Safal, BARI sarisa 7, BARI sarisa 13 and BARI sarisa 6 produced siliqua weight of 0.236, 0.233, 0.199, 0.193, 0.162, 0.146 and 0.135g, respectively. The lowest value of weight/siliqua was observed in BINA sarisa 4 (0.083 g). Pericarp weight/fruit: The effect of raceme position and genotype on pericarp weight/fruit was significant (Table 2). Regarding raceme position, the pericarp weight/fruit was observed higher in proximal region (0.098 g) than in the distal region (0.069 g) (Table 2). Comparison of pericarp weight/fruit were observed significant in B. spp (Table 2). The higher pericarp weight/fruit was observed in BARI sarisa 11, BARI sarisa 8 and BINA sarisa 5 than in the others. BINA sarisa 3, Safal, BARI sarisa 13, BARI sarisa 7 and BARI sarisa 6 produced pericarp weight of 0.087, 0.082, 0.065, 0.062 and 0.059 g, respectively. The lowest pericarp weight/fruit was observed in BINA sarisa 4 (0.043 g). The interaction effect of genotype and raceme position on siliqua size was significant (Table 2). The weight/siliqua was generally smaller in the distal region than in the proximal one in raceme with the degree being varied between the genotypes (Table 2). For example, siliqua weight in BARI sarisa 11, BARI sarisa 7, BINA sarisa 5 and BINA sarisa 3 were significantly greater in the proximal region than in the distal one whereas it was similar in the others (Table 2). The interaction effect of raceme position and genotype on pericarp weight was significant (Table 2). Paricarp weight/fruit was generally smaller in the distal region than in the proximal one in the raceme with magnitude being varied among the genotypes (Table 2). For example, pericarp weight in BARI sarisa 11, BARI sarisa 7, BINA sarisa 5, BINA sarisa 4 and BINA sarisa 3 was smaller in the distal region than in the proximal one whereas it was similar in the others (Table 2). 1000-seed weight: The effect of raceme position and genotype on 1000-seed weight was significant (Table 2). In the general, 1000-seed weight was greater in the proximal (3.481 g) than in the distal region (3.037 g). For variety, BINA sarisa 5 produced significantly higher seed weight (4.00 g) than the BARI sarisa 11 and BINA sarisa 3 (average of 3.5), BINA sarisa 4, Safal, BARI sarisa 6, BARI sarisa 7 and BARI sarisa 13 (average of 3.0). Table 2. Interaction effect of variety and position of raceme (proximal, P and distal, D) on yield and yield attributes in genotypes Variety Raceme position Seed weight /siliqua (g) Weight/ siliqua (g) Pericarp wt. /fruit (g) 1000-seed wt (g) BINA sarisa 3 P 0.130 0.256 0.107 4.00 D 0.074 0.141 0.066 3.00 BINA sarisa 4 P 0.054 0.107 0.054 3.33 D 0.025 0.058 0.031 2.66 BINA sarisa 5 P 0.146 0.281 0.133 4.00 D 0.078 0.184 0.094 4.00 Safal P 0.120 0.219 0.093 3.33 D 0.100 0.166 0.071 2.66 BARI sarisa 6 P 0.086 0.151 0.067 3.00 D 0.069 0.119 0.050 3.00 BARI sarisa 7 P 0.104 0.220 0.083 3.00 D 0.062 0.103 0.041 3.00 BARI sarisa 8 P 0.120 0.254 0.124 3.33 D 0.113 0.218 0.106 3.33 BARI sarisa 11 P 0.188 0.329 0.143 4.00 D 0.135 0.239 0.100 3.00 BARI sarisa 13 P 0.103 0.168 0.072 3.33 D 0.078 0.124 0.057 2.66 LSD 0.05 - 0.0234 0.0524 0.0203 0.527 Reproductive unit, RU = No. of bud + No. of flower + No. of mature and immature siliqua + No. of scar. The interaction effect of raceme position and genotype on 1000-seed weight was significant (Table 2). The thousand seed mass was generally smaller in the distal region than in the proximal region in the raceme with the seed mass being varied significantly between the genotypes (Table 2). The thousand seed mass was similar between proximal and distal region of the raceme in BINA sarisa 5, BARI sarisa 6, BARI sarisa 7 and BARI sarisa 8 whereas it was significantly greater in the proximal position than in the distal one in the rest of the genotypes (Table 2). DISCUSSION In mustard, the inflorescence is a typical raceme and the flowering and fruiting proceeds acropetally resulting in more mature and older fruit in the proximal (lower) region than in the distal (top) position of the rachis. Research results revealed that earlier-formed pods and seeds are heavier in the proximal region than in the distal ones in legumes (Sinha, 1977; Sheldrake et al., 1979; Fakir, 1997). Generally, the genotypes produced more flowers (reproductive unit, RU) but fewer siliqua and seeds in the distal region than in the proximal ones (Table 1). These results agree with the findings in legumes as stated above. Further, the interaction effect of raceme position and variety on flower and siliqua production revealed that flower and fruit production was similar between proximal and distal region of the raceme only in two varieties (BINA sarisa 5 and BARI sarisa 11) (Table 1). In the remaining other genotype either flower or siliqua yield varied significantly between the proximal and distal region. Similarly, the earlier-formed siliqua size (weight/siliqua), seed yield in siliqua (seed weight/siliqua), pericarp weight and seed size (1000-seed weight) were also greater in the proximal region than in the distal position again in two genotypes, BINA sarisa 5 and BARI sarisa 11 (Table 2). It appeared that in the above two varieties more siliquae were produced than could be filled, the later-formed fruits and seeds, therefore, became smaller possibly due to inadequate supply of assimilate from the source. This result agrees with report of Khaton (2004) that earlier-formed siliqua and seeds are heavier in four genotypes of Brassica. These results further indicate that there might be a limitation of ‘source’ that cause smaller fruit and seed size in the distal region in these two particular varieties (BINA sarisa 5 and BARI sarisa 11). Again the similarity in the average weight of earlier- and later-formed fruits and seeds in BARI sarisa 6 and BARI sarisa 8 indicates that the development of siliquae and seeds was not limited by assimilate supply; this in turn indicates that the yield was primarily limited by the number of pod i.e. by the number of sink. Present investigation, therefore, indicate that mustard genotypes may be source or sink limiting. Whenever, the sources is limiting yield could be increased by increasing source activity (Fakir, 1997). However, there may be a second barrier, the inadequate vasculature, especially the inadequate phloem tissue development particularly in the distal region of the rachis of mustard raceme may cause increased abscission of flowers (Haque and Prodhan, 1987). Weibold (1981) in soybean and Mondal et al. (2011) in mungbean studied vasculature and flower shedding and found that inadequate phloem tissue may be responsible for greater flower sheding and smaller yield in the distal part of the raceme. It appeared that reproductive efficiency was affected by proximal and distal positions in the raceme, and yield was possibly limited both by source and sink capacity in mustard. REFERENCES Coffelt, T. A., Seaton, M. L. and VanScoyoc, S. W. 1989. Reproductive efficiency of 14 Virginia-Type peanut cultivars. Crop Sci., 29: 1217-1220. Fakir, M. S. A. 1997. A study of morphophysiological selection criteria related to yield in pigeonpea (Cajanus cajan L. Millsp.). Ph. D. Disst. Dept. Plant Sci. Univ. West Indies, St. Augustine, Trinidad. Fakir, M.S.A. Umahara, P. and McDavid, C.R. 1998. Study of floral abscission in relation to yield in pigeonpea [Cajanus cajan (L.) Millsp.]. Proc. 20th Bangladesh Sci. Conf. Part-2: 119-125, Bangladesh Assoc. Adv. Sci. (BAAS). Fakir, M.S.A.; Hossain, M.A.; Hossain, A.K.Z.; Prodhan, A.K.M.A. and Afsaruzzaman, S.M. 2000. A study of flower production and abscission in country bean (Lablab purpureus). Bangladesh J. Agric. Sci., 7(2): 279-285 Fakir, M.S.A., Khatun, M., Islam, A and Uddin, M.N. 2012. Nodal position effect on reproductive efficiency and seed yield in four mustard varieties. Bangladesh J. Seed Sci. Technol., 16(1&2) (Accepted). Ferranti, F., Frenquelli, G., Gomane, B. and Hampergher, F. M. 1994. Relationship between flowering and seed set in winter rapeseed. Agric. Miditeragea, 124(4): 249-255. Haque, M.A. and A.K.M.A. Prodhan, 1987. Anatomy of mustard plant (Brissica campestris L.) II. Stem and rachis of the inflorescence. Bangladesh J. Bot., 16: 131-140. Islam, A. 2006. Study of some morphological characters and reproductive efficiency in mustard. M. S. Thesis, Dept. Crop Botany, Bangladesh Agric. Univ., Mymensingh. Islam, A. and M.S.A Fakir, 2012. Reproductive efficiency methods and their relationship with siliqua production in Mustard, Bangladesh Agric. Univ. Res. J., 10 (2) (Accepted). Isobe, K., Kokubun, M. and Tsuboki, Y. 1995. Effect of soybean raceme-order on pod set and seed growth in three cultivars. Jpn. J. Crop. Sci., 281-287. Khalid, A. N. M. 1999. Floral abscission and reproductive efficiency in summer and winter tomato (Lycopersicon esculentum Mill) varieties. M. S. Thesis, Dept. Horticulture, Bangladesh Agric. Univ., Mymensingh. p. 29-31. Khaton, M. 2004. Study of canopy structure and flower production in mustard. M. S. Thesis, Dept. Crop Botany, Bangladesh Agric. Univ., Mymensingh. p. 9-13. Mondal, M. M. A., Das, M. L., Malek, M. A. and Khalil, M. I. 2003. Performance of advanced generation rape seed mutants under high and low input conditions. Bangladesh J. Agric. Sci., 30(1): 115-118. Mondal, M.M.A.; Fakir, M.S.A.; Prodhan, A.K.M.A.; Ismail, MR and Ashrafuzzaman, M. 2011. Deflowerinng effect on vasculature and yield attributes in raceme of Mungbean (Vigna unguiculata (L) Wilczek) Aust. J Crop Sci., 5(11):1339-1344. Sheldrake, A. R. and Narayanan, A. 1979. Comparisons of Earlier- and Later-formed Pods of Pigeonpeas (Cajanus cajan (L.) Millsp.). Ann. Bot., 43, 467-473. Shil, R. K. 2005. A study of growth, dry matter production and yield in fifteen mustard genotypes. M. S. Thesis, Dept. Crop Botany. Bangladesh Agric. Univ., Mymensingh.. Sinha, S. K. 1977. Food Legumes: Distribution, Adaptability and Biology of Yield. FAO Plant Production and Protection Paper 3. Food and Agriculture Organization (FAO) of the United Nations, Rome. Tayo, T. O. and Morgan, D. G. 1975. Quantitative analysis of the growth, development and distribution of flowers and pods in oilseed rape (Brassica napus L.). J. Agric. Sci., (Camb.), 85: 103-110. Weibold, J.W., and Panciera M.T. 1990. Vasculature of soybean raceme with altered intra raceme competition. Crop Sci., 30:1089-193. PAGE 18