Pineapple is widely grown in Jimma, Gojeb, Dila, Tepi and Bebeka areas. However, its production is seriously constrained by weed competition and currently no ...
Eth. J. of Weed Mgt. 1(1), 29 – 40 (2007)
Effect of Weed Management on Pineapple Growth and Yield Tadesse Eshetu, Wondyifraw Tefera and Tesfu Kebede Jimma Research Center P.O. Box, 192 Jimma, Ethiopia
Abstract Pineapple is widely grown in Jimma, Gojeb, Dila, Tepi and Bebeka areas. However, its production is seriously constrained by weed competition and currently no recommended weed management is available in these areas. A field experiment was therefore, conducted at Jimma Agricultural Research Center (ARC) from 2001 to 2003.The objectives of this experiment were to evaluate different weed management methods on growth and yield of pineapple. Eight weed management methods either singly or in combination were compared in a randomized complete block design with three replications. The results showed that pineapple was susceptible to weed competition that as weeding intensities increased, vegetative growth, fruit weight and yield increased significantly. The yield loss recorded under different weeding intensities of no weeding, one hand weeding and two hand weeding was 88%, 72% and 30%, respectively compare pineapple. As a result, mulched treatments significantly out- yielded treatments without mulch and the clean weeding with 100% weed control efficiency. Mean fruit yield from mulched treatments was 36 t ha-1, while a mean yield of 18.6 t ha-1 was obtained from treatments without mulch. Intercropping of haricot bean was found as good intercrop for pineapple and gave high yield when integrated with hand weeding and mulching. In addition, mulching conserved considerable amount of soil moisture and also increased total N and soil pH.
Introduction Pineapple (Annanas comosus L.) is a perennial herb in the botanical family Bromeliaceae, native to the American tropics (Bartholomew et al., 2002). It is a hardy tropical fruit cultivated in all tropical and subtropical countries and grows well in frost-free areas between 25o north and south of the equator (Samson, 1986). It is widely grown in Jimma, Gojeb, Dila, Tepi and Bebeka areas and it is a potential cash crop to farmers. According to Edosa (1998), pineapple is highly productive in these areas that yield as high as 60 tons ha-1 has been recorded on experimental plots. Samson (1986) reported that pineapple heavily suffers from weed competition and the use of paper or plastic mulch and timely application of herbicides are the best means of preventing weed competition for high yield. Sison (2000) showed that application of the herbicide sulfentrazone at 0.5 kg a.i ha-1 gave excellent weed control and resulted in significantly higher yield compared to the untreated control. According to Chadha et al. (1997), pineapple because of its inherent slow growth and the wider space between the rows is prone to continual weed
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germination and growth leading to severe competition and as a result, yield reduction could reach as high as complete crop failure at worst conditions. Similarly, Bose and Mitra (1990) reported that weeds pose a serious problem in the cultivation of pineapple especially during the rainy season and manual weeding accounts to 40 per cent of the total production. These researchers also reported that application of herbicide increased yield by 18 per cent compared to that obtained from unweeded plot. Cover cropping is another important practice followed in fruit crops to suppress the growth of weeds, to bring additional income to the grower if the inter crops grown are the right type (Singh et al., 1961). Jimma is characterized by high rainfall and hot humid climate that encourage rapid and continuous growth of the noxious perennials, such as Cyperus spp., Cynodon spp, and Digitaria spp that seriously compete with crops and result in enormous yield reduction (Tadesse, 1998). For example, yield loss assessment studies conducted in Jimma showed a yield loss of 60-80 % for coffee (Tadesse, 1998), 75-100% for soybean and 60-75% for sorghum (unpublished data). Farmers in Jimma area either do not weed pineapple or slash weeds only once in one cropping season and as a result pineapple fields remain weedy throughout the year resulting stunted vegetative growth and small sized fruits (personal observation). Under such ecological condition, identification of effective weed management methods that utilize all available knowledge of cultural, chemical and mechanical methods in combination would be useful for high yield and sustainable pineapple production in Jimma area. As pineapple is highly productive in small land, effective weed management warrant high yield and improve the income of poor farmers. The main objective of the study was to evaluate various weed management methods on weed control, the overall growth and yield of pineapple under Jimma condition.
Materials and Methods The study was conducted on Nitosols naturally weed infested field at Melko. The study was laid in a randomized complete block design with three replications. Smooth Cayenne, a recommended variety for its adaptation, yield and quality was used. Slips of 20 cm length were planted on a plot size of 24 m2. The spacing used was 90 cm, within plants and 60 cm between rows; the distance within the double rows was adjusted to 30 cm, to give rise to plant population of 44, 444 ha-1. The weed management treatments were: • • • •
No weeding (weedy check), One hand weeding in May/June, Two hand weeding as needed, Clean weeding all season (control),
Weed management on pineapple • • • •
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One hand weeding in May, followed by haricot bean intercropping (cover crop) in June and followed by mulching with non-decomposed coffee husk in September (after harvesting the haricot bean ), Mulching with non-decomposed coffee husk in May, followed by a spray with Roundup at 3 l ha-1 as post emergence in July and followed by mulching with nondecomposed coffee husk in September, One hand weeding in May followed by mulching with non-decomposed coffee husk in July and followed by one hand weeding in September, and One hand weeding in may, followed by Roundup spraying at 3 l ha-1 as post emergence in July and followed by one hand weeding in September.
Roundup was sprayed between the rows as post emergence herbicide at the rate of 3 l ha-1 using CP3 knapsack spryer fitted with ICI red polijet nozzle. A recommended haricot bean variety (Gobarasha) was sown between the rows at the rate of 50 kg ha-1 as cover crop. After haricot bean was harvested and threshed the residue was not returned to the plots. For the treatment involving mulching, non-decomposed coffee husk was uniformly applied at a rate of 20 tons ha-1 as per the schedule. Likewise, weeding was done by hand pulling and slashing, when deemed necessary. Soil moisture was determined using the oven method in January (the driest month). Weed species were identified and recorded each year from the experimental plots. The quadrant method was used for weed species identification and determination of their biomass on the experimental plots. Weeds were identified with the reference of guides and manuals. Identification of weed species from each experimental plot was carried out both before and after treatment application. But weed biomass, was determined each year just prior to the end of the rainy season (October). Weed control efficiency was calculated using the formula developed by (Kothari et al., 1989) X (X - Y) / X;
Where X and Y represent weed weights from the weedy check and the particular weed management method being compared, respectively.
Soil analysis Soil samples were taken from each experimental plot at a depth of 30 cm before and after the end of the experiment. Soil pH was determined using a glass electrode pH meter in a 1:2:5 soil/water suspensions. Total nitrogen was determined by Macro Kjeldhal method. Using this data, the carbon to nitrogen ratio was calculated and recorded.
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Statistical analysis Data were analyzed using a PC-SAS program (Version 8e, SAS Institute Inc). Treatment means showing significant differences were statistically separated using the Duncan’s multiple range test.
Results and Discussion Weed growth The major naturally- occurring weed species recorded growing in association with pineapple in the study area is presented in (Table1). All noxious perennial and annual weeds were abundantly growing in the experimental field. Table 1. Major weed species recorded during the study period Botanical name
Family
Digitaria abyssinica Digitaria scalarum Cyperus spp. Cynodon spp. Bidens pilosa Plantago lanceolata Ageratum conyzoides Galinsoga parviflora Oxalis spp.
Poaceae Poaceae Poaceae Poaceae Compositae Plantignaceae Compositae Composaitae Oxalidaceae
Growth nature Perennial Perennial Perennial Perennial Annual Annual Annual Annual Annual
Eco-physiological definition C4 (shade avoidant) C4 (shade avoidant) C4 (shade avoidant) C4 (shade avoidant) C3 (shade tolerant) C3 (shade tolerant) C3 (shade tolerant) C3 (shade tolerant) C3( shade tolerant)
Economic importance Noxious Noxious Noxious Noxious Noxious Noxious Noxious Important Important
C3= weed species which require more radiation for growth C4= weed species which require less radiation for growth
Weed biomass was significantly (P
