ABSTRACT
An experiment was conducted at the Teaching and Research farm of the Department of Crop Science, Faculty of Agriculture, University of Nigeria, Nsukka in the 2006 cropping season, to assess the effects of planting distance and organic manure rates on yield and nutrient composition of waterleaf at Nsukka. in Southeastern Nigeria. Treatments comprised five planting spacings and four manure rates. The planting spacings were 25cm x 10cm, 25cm x 15cm, 25cm x 20cm, 25cm x 25cm and 25cm x 30cm corresponding to 1,000,000; 444,444; 250,000; 160,000 and 111,111 plants per hectare, respectively. The manure rates were 0,10,20 and 30t/ha, and the nutrients were nitrogen (N), calcium (Ca), phosphorus (P), potassium (K), magnesium (Mg) and iron (Fe). Also vitamins A, B and C were investigated. All possible combinations of spacing and manure rates were laid out in a factorial arrangement using randomize complete block design in twenty treatment combinations per block, and there were three replications. The closest spacing of 25cm x 10cm gave the highest waterleaf vegetable yield, and yields generally decreased with progressive harvests. Yields tended to decrease with wider spacings. Vegetable yield was significantly lowest with where no manure was applied. Application of manure at 30t/ha significantly
Yield higher than application of either 10t/ha or 20t/ha. Combination of organic manure at 30t/ha with 25cm x 10cm spacing gave the highest yield while combining manure at 30t/ha with the spacing of 25cm x 20cm followed in yield improvement. Marketable vegetable yield was significantly increased with successive increment in the manure rate. Where no manure was applied, yield was greatly depressed by over 58%. The dry matter yield of waterleaf decreased as the spacing increased with 25cm x 30cm spacing giving the lowest dry matter yield and the closest spacing of 25cm x 10cm giving the highest dry matter yield. The moisture content of the leaf was high all through the harvest periods being as high as 89% on the average. The ash content and fibre were low while fat was in trace quantity in the stem and in the inflorescence. Studies on the elemental content of the vegetable indicated that there are no significant effects of manuring on the Mg, Ca Fe and on the N, P and K contents of the leaf. There were no clear effects of manuring on the vitamins A, B and C in the leaf or in the stem or in the inflorescence fractions of the waterleaf vegetable.
CHAPTER ONE
INTRODUCTION
Waterleaf, Talinum triangulare is one of the most widely consumed vegetables in southeastern Nigeria (van Epenhuijesen, 1974). It is a dicotyledonous plant belonging to the family of Hydrophyllaceae. In some places in Nigeria, it is often considered to be a weed and only a few people in sub-Saharan Africa recognized it as a potential vegetable (Schippers, 2000). Schippers (2000) stated that as the name triangular implies, it is best recognizedby its triangulare peduncle. The Yorubas call it ‘gbure’ whereas the Igbos call it ‘mgborodi’, in Sierra Leone, it is referred to as ‘bologi’ while in Cameroon, it is called ‘elok-sup’ (Scippers,2000).
Waterleaf is a small glabrous herbaceous plant in growth habit and is well adapted to areas close to rivers and streams. In the Southern part of Nigeria, where it is abundant, it is found growing in both wild and domesticated states (Williams et al., 1991). Triangulare is regarded as a volunteer crop, which comes up immediately after the first rains of the year, usually around March/April. The crop is mostly grown b woman and children (Ekpe and Obiefuna, 1977).
The leaf is alternately arranged on the stem. It is sessile, succulent and usually not longer than 7.5cm. In a light shade it can reach up to 11cm in height. The leaf is oblanceolate with pointed tips, and usually falls soon after the start of the dry season. The stem is thick, and bright green with numerous hairs. The inflorescences are terminal, 7-15cm long, with three sided stalks carrying racemes of flowers.
The rigid pedicels, measuring about 1cm long, bend down when the
Seeds are mature (van Epenhuijsen, 1974). The flowers are deep pink and open only in the mornings. Each has two sepals with three dark green nerves. The flowers dry up and fall before the fruits are ripe. Uzo and Peregrine (1991) summarized the major biology of the crop and reported that it is a perennial, with the underground portion perenating to grow again after the dry season.
According to van Epenhuijsen (1974), waterleaf is also drought tolerant like some other vegetable crops such as fluted pumpkin. It has the ability to ratoon in the following year with the early rains. It thrives well under a wide range of soil conditions, but does better in a well-drained sandy loam soil rich in organic matter (Thompson et al., 1975).
Talinum triangulare is a vegetable that is grown because of its wide variety of uses and mainly consumed in the south-south areas of Nigeria. The leaves and tender shoots/stems are used as browse plant for feeding livestock and may be used as a green manure crop. The young leaves and tenders shoots are also consumed as pot herbs (van Epenhuijsen, 1974). Waterleaf is recognized as a crop that is important for its palatable and nutrients leaves. (Akoroda (1990)) reported that the leaves of fluted pumpkin and other vegetable leaves like waterleaf leaf could be used for local vegetable soup especially in Southern Nigeria. For example, waterleaf is one of the soups in the ingredients in the preparation of the popular local dish called “Edikang-ikong” soup in the South-South Area of Nigeria, like Calabar, the Cross River State, and in other vegetable soups, and in stew.
Asiegbu (1984) who worked on Telfairia occidentalis reported that with the need for fresh vegetables at all times, sequential establishment over a period of time can be employed to extend the period of availability and harvest of certain vegetables. Waterleaf may be established in August or September so as to be available for profitable sale in the dry season when vegetables are scarce. Propagation of the crop could be both by seeds and by cuttings, and according to van Epenhuijsen (1974) propagation by cutting is better.
Manures are substances, which are obtained as decomposition products of plant and animal remains and capable of supplying plant nutrients in readily available form that support good crop growth (Yeqiang, 2006). They are bulky in nature, and have no definite composition (Das, 1999). Organic manures contain nutrients in small quantities, and therefore, large quantities will be needed to be applied per hectare. Organic manure provides food for soil micro-organisms. It increases the activities of soil microbes and in turn helps to convert unavailable plant nutrients into available forms. It also increases the cation exchange capacity (CEC) of the soil, thereby preventing the loss of nutrients through leaching as it retains them in available forms (Das, 1999). Organic manure also improves the water holding capacity of the soils, releases nutrient slowly, promotes growth of earthworm and other beneficial organisms in the soil (Thompson et al., 1975).
Plant spacing is a very important measure a farmer can employ to optimize yield of crops, yet this is often neglected by the local farmers. It has been shown that one of the most critical aspects of optimizing crop growth and indeed yield is
Maintaining adequate crop geometry in terms of spacing. According to schippers (2000), proper spacing allows for less competition from weeds. Schippers (2000) also suggested that in waterleaf, if the soils are fertile or when manure is used in such a way that plant develop rapidly with large leaves, spacing should be increased proportionately. Among the farmers that grow waterleaf in Nigeria, especially in Akwa-ibom and Cross River States, definite plant spacing has not been considered or adopted hence, the need to investigate the optimum crop production for yield maximization (Ekpe and Obiefuna, 1977).
In the Sudan where an estimated 3,000 hectares of the crop were grown, yields of about 20t/ha of waterleaf can be obtained, mainly under irrigation (Schippers, 2000). This yield was considered to be low, and adoption of appropriate plant spacing especially under varying soil fertility levels will aid in yield improvements. The present low production status of waterleaf could also be attributed to low fertility of soil and poor management (Ekpe and Obiefuna, 1977).
There is currently no production technology package developed for waterleaf yield optimization. The manure recommendations at the rates of 20t/ha, 30t/ha for waterleaf based on investigation conducted at Uyo indicated that organic manure influenced the yield of waterleaf. It is therefore, necessary that studies be carried out in various locations in Nigeria for more data for optimum waterleaf production recommendation, especially under varying plant spacings.
Literature search has revealed that information on agronomic technology package for profitable production of waterleaf is very scanty. The production factors, which appear to require immediate attention, are plant spacing and manure needs for optimum yield of waterleaf vegetable.
Therefore, the objectives of the present study were:
- To optimize growth and vegetable yields of waterleaf through choice of plant spacing and/or organic manure rates.
- To determine the best combination of plant spacing and organic manure rate for optimum vegetable yield under the prevailing conditions at Nsukka.
- To determine the nutrient composition of waterleaf vegetable as influenced by manuring.
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