Short communication
Bunch stalk feeding of urea in banana
Musa
(AAB group) `Nendran'
T.K. Ancy, S. Kurien
*College of Horticulture, Vellanikkara, Thrissur 680 656, Kerala, India
Accepted 19 August 1999
Abstract
The in¯uence of urea feeding at the cut bunch stalk end of the rachis of banana was studied in tissue culture plants of `Nendran' banana having uniform sized bunches. A preliminary study for standardising the dose of urea showed the superiority of placing 30 g urea on two-week-old bunches. The main experiment on bunch stalk feeding, also revealed that placing 30 g urea on the cut stalk end at two weeks or at four weeks after complete emergence of the bunch resulted in maximum yield and other elite yield attributes. Bunch weight, ®nger weight, length and grade of `D' ®nger and ®lling index are the yield parameters mostly affected by the bunch stalk feeding.
#2000 Elsevier Science B.V. All rights reserved.
Keywords: Banana; Urea placement; Yield and yield attributes;Musa; Urease
1. Introduction
Bunch management in banana is a concept gaining in importance and even simple techniques of bagging/sleeving/covering (Trupin, 1959; Perumal and Adam, 1968; Walker, 1975; Istraeli et al., 1980; Daniells et al., 1987, 1992; Johns and Scott, 1989) and male bud pruning (Simmonds, 1959; Sampaio and Simao, 1970; Walker, 1973; Meyer, 1975; Jaramillo, 1982; Amma et al., 1986; Daniels et al., 1994; Irizarry and Rivera, 1991; Irizarry and Goenaga, 1995; Galan Sauco et al., 1996) increase yield, ®nger weight and size of harvested bunches. Most
*
Corresponding author: fax:91-487370019. E-mail address: [email protected] (S. Kurien).
management practices in banana have previously focused on either the soil or the plant growth parameters and very seldom directly on the bunch.
Only a few reports on bunch stalk feeding of urea in banana are available. Post-shooting application of urea in cv. Giant Cavendish bananas, has been reported to promote the yield (Venkatarayappa et al., 1976). It was inferred that yield increments were due to more availability of urea in aqueous form at later stages and for a prolonged period. Similar positive results were later reported by Buragohain and Shanmugavelu (1986) in banana cv. `Vayal Vazhai'. According to them, a 23% increase in banana weight was obtained by attaching 10 g urea in a polythene bag to the cut stalk end immediately below the bunch two days after the male bud was removed.
Translocation of nutrients in the infructescence of banana cvs. Poovan, Monthan and Nendran has been reported by various scientists (Buragohain and Shanmugavelu, 1985; Sobhana and Aravindakshan, 1989). The bene®cial effects of late application of fertilizer are evident from these experiments.
In the present study, the potential impact of urea placement at the cut stalk end on yield and yield attributes in banana cv. Nendran, the most important clone of the state, was investigated. The objective of the study was to standardise the optimum dose of urea and time of placement so as to get maximum output with minimum inputs.
2. Materials and methods
2.1. Experiment 1
Two-week-old, uniform bunches were selected and the rachis cut at a distance of 15 cm from the last hand adopting the `¯at' cut method and were supplied with different doses of urea viz., 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 g and compared with two controls (control and system control). The distance of the cut from the last hand and the type of cut were pre-standardised from previously conducted experiments. The ¯at cut was effected by giving a cut perpendicular to the bunch stalk, and then the cut was wrapped with the de®nite amount of urea in a polythene sheet and retained in position till harvest. The experiment was laid out in completely randomised design (CRD) with three replications.
2.2. Experiment 2
complete emergence of the bunch, and no pruning (control) formed the 21 treatments. The experiment followed a completely randomised design and was replicated twice with a single plant receiving one treatment in each replication.
All plants received uniform cultural and management practices as per Kerala Agricultural University package of practices recommendations (KAU, 1993). The data on yield and `D' ®nger weight (Gottreich et al., 1964) were obtained by weighing the bunch and respective ®nger. The `D' ®nger characters were recorded directly whereas the ®lling index was calculated using the formula: convex length/weight (Stover and Simmonds, 1987). The data were analysed using the analysis of variance technique except in yield where analysis of co-variance was used with the number of ®ngers being taken as a co-variate, thereby avoiding any possible error (Panse and Sukhatme, 1978).
3. Results
3.1. Experiment 1
The data presented in Table 1 show a signi®cant in¯uence of all doses of urea except 70 g and of pruning on bunch weight. But among the treatments, a
Table 1
Effect of doses of urea on yield and yield attributes in banana cv. `Nendran' (®gures in parenthesis denote the number of ®ngers taken as a co-variate in ANCOVA)
Doses of
Control (pruning) 5.72abc(35.7) 166.67a 22.83ab 13.00ab 7.29ab 10 6.52ab(33.0) 166.67a 23.67*ab 13.50ab 7.05ab
SEm (21 df) 0.4281 10.23 0.67 0.30
*Signi®cant **
maximum bunch weight of 7.05 kg was recorded by placing 30 g of urea on the cut stalk end. The next heaviest yield was from the 40 g urea treatment followed by 10 and 60 g which were on a par. However, higher doses, i.e. > 50 g were not acceptable due to premature ripening and rotting of the last hand on the plant itself. The lowest bunch weight of 4.24 kg was recorded on the control.
There were also signi®cant differences regarding ®nger weight and size in favour of the treatments with urea. Maximum ®nger weight (186.79 g) was observed in the 30 g urea placement treatment which differed signi®cantly from all other treatments and the control which in turn also differed signi®cantly from all treatments (121.67 g). Treatments above 50 g showed premature ripening and blackening of the terminal ®ngers and hand which were more proximal to the treatment.
70 g urea placement followed by 10 and 40 g urea treatments recorded the maximum ®nger length. They were on a par with all other treatments except one (90 g urea) and the control, which had the lowest lengths of 21.67 and 19.33 cm, respectively.
The greatest girth (14 cm) was recorded in the 30 g urea placement treatment but most other treatments were not signi®cantly different from one another. The ®lling index showed non-signi®cant differences between treatment means, eventhough, in comparison with the control (6.41) the 30 g urea placement treatment showed higher values of the ®lling index (7.83).
3.2. Experiment 2
A perusal of the data presented in Tables 2 and 3 reveals statistically signi®cant differences in bunch weight between the treatment means. The treatment combinations of pruning two weeks after emergence with 30 g urea placement followed by pruning 4 weeks after emergence and 30 g urea placement gave the best results. In general, the superiority of applying 30 g urea was very evident (Fig. 1).
Finger weight, length and grade were much in¯uenced by urea feeding, though not signi®cantly. Fingers of 240 g weight in comparison with control (165 g) were yielded by pruning 2 weeks after emergence and 30 g urea. The longest fruits (24 cm) were obtained in combinations of 2 weeks10 g urea, 2 weeks40 g
urea and 3 weeks30 g urea placements and the control measured only
20.03 cm. Most of the treatments produced a better grade than the control. In this respect, the best grade came from combinations of pruning after 4 weeks30 g
and pruning 2 weeks after30 g urea placements which recorded 14.48 and
14.06 cm, respectively.
Table 2
In¯uence of bunch stalk feeding of urea on yield and yield attributes in banana cv. `Nendran' (®gures in parenthesis denote the number of ®ngers taken as a co-variate in ANCOVA)
Time of male bud Control (no pruningno urea) 8.04 (43.0) 173.13 20.03 12.06 8.34 SEm (18 df) 0.8648 24.298 1.4374 0.4686 0.6625
(SEm 35 df)
Table 3
Summary of ANCOVA
Source df Significance
Bunch weight `D' finger Length Girth
pruning after 2 weeks with 30 g and pruning after the 1st week 30 g urea
placements recorded ®lling indices of 10.7, 10.55 and 10.2, respectively.
4. Discussion
Experiment 1 revealed that male bud pruning and urea placement with an optimum dose of 30 g enhanced the yield signi®cantly while in the main experiment (Experiment 2) treatments involving placement of 30 g of urea and pruning 2 weeks after emergence, 4 weeks and 1 week after emergence were generally superior.
The urea feeding which in turn in¯uenced the ®nal yield, can be explained in view of certain statements. Calvin et al. (1952) reported that in plants allantoin and allantoic acid seem to be more immediately concerned with the synthesis and use of nitrogen they contain, and these compounds may be derived from glyoxylic acid, with urea as a possible donor.
Urea levels of > 50 g should lead to the fast absorption of a large quantity of nutrients (in the form of NH3) by the last hand but the concentration of the
nutrients may have exceeded certain critical limits which caused the blackening and rotting and ®nally yield reduction that was observed.
A higher ®lling index due to better nutrient allocation, clearly explains the reasons for an increase in ®nger weight. It can be inferred that the nutrients were utilised more for cell elongation of the fruit rather than cell multiplication and the cell enlargement resulted in more length than girth. The urease activity also coincided with lengthening of the fruit (Ancy et al., 1998).
Higher levels of urea supplied at later stages, as well as smaller quantities supplied immediately after bunch opening led to inferior ®nger size. In a study on the morpho-physiological aspects of ®nger development it was observed that in the ®nal stage of development, cell enlargement took place thus reducing the available air space followed by starch ®lling in the cells (Kurien et al., 1999). It could be inferred that when urea was applied early starch ®lling took place in the cells which were under developed. The late application of urea, coinciding with or after the stages of cell division, when the early nitrogen pool becomes exhausted, may be involved in fruit development as a nitrogen source.
Acknowledgements
The authors acknowledge the help of Director of Research and Associate Dean, Kerala Agricultural University for the funds and facilities for conducting the experiments.
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