Effects of Plant Spacing and Organic Manure Rates on Yield and Nutrient Composition of Waterleaf (Talinum Triangulare)
CHAPTER ONE
Objectives of the Study
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.
CHAPTER TWO
LITERATURE REVIEW
Talinum triangulare is a vegetable that is grown because of its wide variety of uses (Schippers, 2000). The leaves and tender shoots/stems are used as browse plant for feeding livestock, and may also be used as a green manure crop. The young leaves and tender shoots are also consumed as pot herbs (van Epenhuijsen, 1974).
Waterleaf is recognized as a crop that is important for its palatable and nutritious leaves. According to van Epenhuijsen (1974) yield of waterleaf in improved production system in more favourable environment with inputs of organic matter demonstrates that waterleaf has extremely high yield potentials. Van Epenhuijsen (1974) also stated that yields may be as high as 20 to 30t per hectare. Uzo and peregrine (1991) reported that although waterleaf yields from farmers` fields are low, favourable growing conditions can result in high yields of 2 to 3 tons of leaves and shoots per hectare from single bed containing 56 stands. The authors also reported that with appropriate agronomic practices such as fertilizer application, timely weeding, yielding may often exceed 4 tons and some have been greater than 4.5 tons per hectare.
In Sudan where an estimated 3,000 hectares of the crop were grown, yields of about 20t/ha was obtained, mainly under irrigation (Schippers, 2000). This yields was considered to be low, and adoption of appropriate plant spacing especially under varying soil fertility levels would 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).
The productivity of waterleaf may again be low because it is often grown under poor agronomic conditions such as lack of weeding, non application of manure to increase yields, and inadequate control of pests and diseases (van Epenhuijsen, 1974). These pests and diseases would result in loss of leaves thereby reducing the yield potential of the crop.
Among the diseases of the crop include the leaf rot, which causes rotting of the leaves and pests such as Zonocerus variegates defoliate the leaves, and render them unacceptable to the buyers, and in turn reduce their market values tremendously as reported for Telfaira occidentalis( Akoroda, 1990a).
Waterleaf may be established in August or September so as to be available for profitable sale in the dry season when vegetables are scarce. Asiegbu (1984) who worked on Telifairia occidentalis reported that with the need for fresh vegetables at the times, sequential establishment over a period of time could be employed to extend the period of availability and harvest. It was reported on Telfairia occidentalis that if leaves were not harvested on time, the leaves would become coarse and unaccepted for human consumption and thereby unacceptable to the market (Akoroda, 1990b). Akoroda (1990a) equally suggested that ideal cutting interval for vegetable including waterleaf is between two to four weeks in order to obtain maximum production of vegetable yield. Propagation of the crop could be both by seeds and by cuttings, and according to van Epenhuijsen, (1974) propagation by cutting is better.
Effects of weathers on Plant Growth Walter (1996) identified rainfall as the one factor which has the greatest effect on plant growth in the tropical regions.
Rainfall plays a major role in nutrient solubility and absorption. Generally, some certain amount of rainfall such as 250mm of rainfall that is well distributed are needed for growth and development of waterleaf vegetables.
According to Jones (1998) leaching would become more rapid with more frequent rains, thus reducing soil nitrogen status and nitrogen uptake by vegetables.
Fakorede (1999) observed that high cloud cover characteristic of rainy season lowers solar radiation. Temperature is high when the humidity is reduced.
Effects of Organic Matter
Manures are substances which are organic in nature, used for farming operation and are capable of supplying plant nutrients in readily available form that supports good crop growth (Yeqiang, 2006). Decomposed materials of plant and animal origin have been used for many years to improve soil conditions for crop growth. According to FAO (1998), manures and composts were the only source of nutrients for crops before the introduction of mineral fertilizers. The organic manure promotes the activities of beneficial soil organisms such as earthworm and other microbes. They are bulky in nature, have no definite composition and are mostly obtained from plant and animal waste products Das (1999). Organic manure contains nutrients in small quantities and therefore, large quantities would be needed to be applied per hectare (Yeqiang, 2006). According to Das (1999) the nutrient elements found in cow dung were made up of 0.4% N, 0.2% P and 0.3% K.
CHAPTER THREE
DISCUSSION
Nsukka is located in the derived savanna region of Nigeria at latitude 06o 21’N and longitude 07o 24/E, and at altitude of 447.2m above sea level (University of Nigeria, Nsukka meteorological station). The soil textural class was a sandy loam characterized as an ultisol.
The number of leaves per stand at first harvest appeared relatively greater than the number at subsequent harvest. This could be attributed to the relative short regrowth periods allowed before subsequent harvest compared with the length of time for the initial growth from planting to first harvest.
The enhanced growth response by the waterleaf in the treated plots compared to where no manure was applied suggested that the organic manure probably affected nutrient release and the amount of nutrients available to the root for absorption and utilization for growth. An earlier report by Thompson et al., (1975) on the composition of organic manure showed that it is usually high in N and K.
CHAPTER FOUR
RESULT
The soil of the experimental site was characterized texturally as a sandy loan (Table 1). The soil reaction was acidic, being low pH and high in exchangeable acidity. The N,P and K contents were considered low. Magnesium and Calcium contents and base saturation were also low.
In 2006, the monthly rainfall and rain days were highest in October, lowest in November while it did not rain in December (Table 2). The months of February were lowest in December and November. The month of April had the highest soil temperatures while August had the lowest. Solar radiation was generally high throughout the year, being lowest with the month of August. The month of August had highest relative humidity while the months of December and January had the least.
During the first harvest, the fresh vegetable marketable yield was highest with the closest spacing of 25cm x 10cm which yielded higher than the 25cm x 15cm and 25cm x 20 cm spacing (table 3). Generally, yields tended to decrease with wider spacing in all the harvests. Vegetable yield was significantly lowest with where no manure was applied than in cases of applied manure.
CHAPTER FIVE
SUMMARY AND CONCLUSION
A field and laboratory experiments were conducted to study the effect of plant spacing and organic manure on yield and nutrient composition of waterleaf. the field experiment was conducted in 2006 and comprised five planting distances and four manure rates. The five planting distance were 25cm x 10cm, 25cm x 15cm, 25cm x 20cm, 25cm x 25cm and 25cm x 30cm, while the four manure rates were 0,10,20, and 30t/ha piggery manure. Experiment 11 was a laboratory experiment in which case the following elements were investigated in waterleaf vegetable, N, Fe, Ca, P, K, Mg and proximate analysis such as fibre, Ash and Moisture and some vitamins such as vitamin A Vitamin B and Vitaminc C.
The field experiment showed that the fresh vegetable marketable yield was highest with the closest spacing while yields tended to decrease with wider spacings. Adequate manuring is absolutely necessary for high yields. Manure rate of 30t/ha was found satifactory. Application of manure at 30t/ha significantly yielded higher than application of either 10t or 20t/ha of manure. This showed that yield increased with the successive increment in organic manure rate. Combination of organic manure at 30t/ha with 25cm x 10cm spacing gave the highest yield. Where manure was not applied, yield was greatly depressed by about 58.8% on the average.
The laboratory experiment showed that the moisture content of waterleaf was generally high all through the harvest periods at an average of 89%. The Proximate analysis showed that
waterleaf vegetable contains high percentage of protein but low in ash and fibre. The vitamins investigated upon were only found in the leaf fraction of the waterleaf vegetable only.
The organic manure increased the mineral content of the waterleaf vegetable. Mineral analysis result obtained varied with their composition in the plant fractions. N, K and Fe showed higher values in the inflorescence fraction than in the leaf or stem fraction while Ca and Mg showed very similar values in the plant fraction. The dry matter yield of waterleaf decreased as the spacing increased with 25cm x 30cm spacing giving the lowest dry matter yield while dry matter yield was highest with the spacing of 25cm x 10cm.
Based on the above findings, it is apparent that for a high leaf yield, the closer the planting distances the higher the leaf yields to be obtained. Therefore, 25cm x 10cm planting distance and 30t/ha of organic manure rate should be encouraged and adapted.
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