Rice – Effect Of Organic And Inorganic Fertilizer On The Growth And Yield Of Three Lowland Rice Varieties
Rice – Effect Of Organic And Inorganic Fertilizer On The Growth And Yield Of Three Lowland Rice Varieties
Rice (Oryza sativa .L.) belongs to the grass family Poaceae, genus Oryza and tribe Oryzaea. It has many species that are distributed all over the world. Most important species include Oryza sativa L. O. glaberrima steud, O. perennis, moench, and O. nivara sharma et shastry etc. Globally, rice ranks third after wheat and maize in terms of production, but in terms of importance as food crop, rice provide more calories, hectare than any other cereal crop. It is an important staple food of about half of the human race, and for almost half of the world population (Schalbroeck, 2001), grown over an area of 43 million hectares with a production of 84.7 million tons (Siddiq, 2000).
Rice (Oryza glaberrima steud) has been cultivated in Nigeria for the past 3500 years. The main production ecologies in Nigeria are rainfed lowland, rainfed upland, irrigated lowland, deep water/floating and mangrove swamp. Nigeria is one of the many countries of the world with suitable ecologies for different rice varieties which can be harnessed to boost rice production to meet domestic demands and even have surplus for export. At the continental level, the country contributes 5 percent of rice land area and 4 percent of rice production. Nigeria produces about 1.35 metric tones of rice per hectare, which is below the world average of about 2 metric tones. The country is therefore deficient to the tone of a million tones making her a net importer of rice (WARDA 2002). Nigeria, however, has potential land area of between 4.6 to 4.9 million hectares for rice production. Considering the heavy demand of rice and the scope of quality rice in international market, interactive research work in almost all aspects of rice is needed, including the determination of fertilizer type and dosage that would be adequate to increase production.
Fertilizer is any material, organic and inorganic, natural or synthetic which supplies plants with the necessary nutrients for plant growth and optimum yield. They are salts which farmers add to the soil in order to increase the supply of nutrients to the crops (Russels,). It is divided into two types: organic and inorganic fertilizers. Organic fertilizers are natural materials of either plant or animal origin including livestock manure, green manure, crop residues, household waste etc. Organic fertilizer is an effective agent for improving soil quality in the long term. Being from waste products, it reduces the cost of agricultural production (Havlin et al, 2005). The organic manure is the store house of nutrients especially nitrogen. It greatly influences the exchange capacity of the soil and has the ability to change both the physical condition and the fertility status of the soil. Organic manure increases the water holding capacity of the soil which is essential for sandy soils. It also improves aeration in clayey soils. There are many types of organic manure material such as cattle dung poultry droppings, leaf mould or compost manure etc.
Inorganic (mineral) fertilizers are fertilizers mined from mineral deposit with little processing, or industrially manufactured through chemical processes (e.g. urea). Inorganic fertilizers vary in appearance depending on the process of manufacture. The particles can be of many different sizes and shapes (crystals, pellets, granules or dust) and the fertilizer grades can include straight fertilizers, compound fertilizers and fertilizer blends.
Nutrients supplied exclusively through chemical source, may enhance yield initially, but the yields are not sustainable over the years. Even the introduction of high yielding varieties and intensive cultivation with excess and imbalance use of chemical fertilizers and irrigation showed reduction in the soil fertility status and about 38 percent of rice crop production (Singh et al, 2001). Problems associated with the use of chemical fertilizers have led to renewed interest in the use of renewable sources (organic manures/wastes) and prompted the scientists to find out an alternative agricultural system which involves the farming i.e. crop and animal husbandry in a way that harmonize rather than conflict with natural processes operating in a natural ecosystem (Sharma, 2001).
The objective of this work is to compare the effects of organic and inorganic fertilizers on the growth and yield of three lowland rice varieties.
THE RICE PLANT
The identification of the rice plant parts is essential in differentiating rice plant from weeds (IRRI, 2002).
Rice is a typical grass forming fibrous root system bearing erect culms and developing long flat leaves. It has a semi aquatic life style requiring water particularly during the reproductive growth phase. It forms multiple tillers consisting of culms and leaves with or without a panicle. The panicle emerges on the uppermost node of a culm from within a flag leaf sheath and bears the flowers in spikelets. The culm consists of a number of node and hollow internodes that increase in length and decrease in diameter up to the length of the culm. The primary tillers emerge from the nodes near the base of the main culm and secondary and tertiary tiller emerge sequentially from these.
The leaf forms a collar or juncture between the sheath and blade and a ligule and two auricles develop on the inside of the junction and base of the leaf blade respectively. Cultivars can vary widely in the length width, colour and pubescence of the leaves. The panic emerges from the flag leaf sheath and consists of a central rachis with up to four primary braches at each node. Primary, and secondary braches bear the flower spikelet has a single floret and two glumes. It is enclosed by a rigid keeled lemma which is sometimes extended to form an own and practically envelops the smaller palea. The floret contains six stamens and a single plumose ovary with two branches. At anthesis, two lodules at the base of the floret swell and force the lemma and palea apart, as the stamens elongate and emerge. The stigma is sometimes exposed as well.
The fertilized ovary is a caryopsis, meaning a small single seeded dry fruit with the pericarp and seed coat fused. It is commonly called a grain. The grin consists of an embryo endosperm pericarp and testa surrounded by the husk or hull.
Growth and Development of the Rice Plant
Under different climate and cultural conditions the growth and developmental stages of the rice plant is complex. Growth of the rice plant can be divided into three developmental stages: the vegetative/germination stages, the reproductive stage and the grain filling and ripening or maturation stage (International Rice Research Institute, 2002). These developmental stages influence the three component of yield; the number of panicles (heads) per unit of land area (square foots, acre, hectare); the average number of grains produced per panicle and the average weight of the individual grains. The combination of these components determines the grain yield.
The Vegetative/Germination Stage
The vegetative growth stage begins with the germination of the seed and ends with the development of panicle buds, i.e panicle differentiation.
After imbibitions of the seed, germination begins with the emergence of the coleorhiza (the sheath covering the embroyonic primary root) and coleoptile from perciarp. The radicule gives rise to the seminal root system which has limited branching. Germination can occur under aerobic or anaerobic condition. Under anaerobic conditions coleoptile emerges first, as it is the only part of the embryo that can grows under energy derived solely from fermentation (Moldenhaur and Gibbons, 2003).
During this early phase of development the plant can produce a leaf every four to five days as the primary culm develops. As the rice plant grows, primary tillers begin to emerge from the axial node of the lower leaves. These gives rise to the secondary tillers from which tertiary tillers can also develop. The internodes begin to elongate at or near panicle initiation (moldenhaver and gibbons, 2003).
The Reproductive Stage
The reproductive stage of rice plant is defined as the period beginning with panicle differentiation and ending when 50% of the florets have been pollinated (WARDA, 2002). Active pollination and fertilization of the embryos begin shortly thereafter.
As the panicle grows inside the flag leaf sheath, senescence of the lower leaves begins. A further these leaves develop before heading (panicle emergence) occurs?. The panicle may emerge partially or full and greater emergence is selected for in cultivars as means of decreasing disease occurrence (Molderhauers and Gibbons, 2003). Flowering typically begins one day after heading and continues down the panicle for approximately seven days until all florets on the panicle leave opens. Pollen is usually shed onto the florets of the same panicle resulting in self fertilization (IRRI, 2002).
Grown- Filling and Maturation Stage
Grain –filling and maturation is the last developmental stage the rice plant. The grain filling and maturation stage of development begins when half the florets have been pollinated (WARDA 2002).
Once the florets are fertilized, the ovaries begin to develop into grain. Initially the grain fills as starch. The panicle remains green at this stage and begins to bend down wards. Leaf senescence continues from the base of the tillers but the flag leaf and next two lower leafs remain photosynthetically active. The grain then begins to harden into soft dough stage. Husks begin to turn from green to yellow and senescence of the leaves and tillers at an advanced stage. During the final stage, the grain matures, becoming hard and dry. The entire plant begins to yellow and dry out at which point the grain can be harvested (IRRI, 2002).
Rice Reproduction Characteristic Flowering
Flowering occurs during and shortly after heading when the florets open, are pollinated and close. The florets which are first exposed to the atmosphere will flower first, about I day after the emergence of the floret. The flowering process, therefore, last from 3 to 5 days, depending on the size of the panicle and how fast the panicle emerges. Each floret will open, shed its pollen and close, never to open again. A floret must pollinate to produce a grain. Under normal conditions, flowering occurs from ? to 1 pm, and florets will remain open for about 40 minutes to 2 hours. High winds and low temperatures seriously hinder pollination and pollen dispersal.
Rice is a self-pollinating crop because there is little chance (0.4%) that pollen from another rice plant will reach the stigma. As the floret approaches flowering time, the filament begins to elongate and the other (bearing the pollen) begins to swell. As the spikelet opens, the anthers burst before foreign pollen can be introduced. If pollination does not occur during this flowering period, the floret will not produce a grain. Sunshine during the flowering period is essential for good pollination (WARDA, 2002).
Rice breeders are reported to observe greater out crossing when honey bees are present (Gealy, et al 2003). Although wind assisted pollen dispersal distances have been estimated up to 110 meters (song et al, 2004).
Pollen is short lived with most pollen grain losing viability after five minutes under typical environmental conditions. Pollen grain morphology changes drastically after shedding from the anther. It is recommended that buffering isolation zones wider than 110m or consisting of tall crops such as sugarcane to prevent gene few (Den Nijs, et al 2024) is essential.
Seed dormancy in rice plant is important in tropical species and cultivars, as a means of preventing pre-harvest sprouting (germination of seeds in the panicle) if the conditions are warm and wet before harvest. Seed dormancy is a mechanism that delays the germination of seeds in the presence of suitable germination conditions. In wild plant species, variable dormancy can be a useful adoption, preventing competition between seedlings resulting from simultaneous germination (Gu, et al: 2004). In some rice varieties, dormancy allows the seeds to remain viable but not germinated in the soil for several years (Moldenhauer and Gibbons, 2003).
As more carbohydrate is transported to the developing grain, it begins to lose moisture (WARDA, 2009). The developing grains are compressed within the lemma and pales (hull) and is molded into its final shape. The developing grain then goes through the soft medium and hard dough stages. These terms describe the texture of the developing grain as it losses moisture.
Environmental Requirement of Rice
The chemical properties of the soil do not appear to be as important as the physical ability of the soil to hold a flood (SCOH et al: 2003). WARDA (2009) summarized that a soil with good drainage and good water retention capacity (containing some clay and or organic matter i.e. loamy soil), is suited for rice production. However, individual cultivars do not span this entire geographic and environmental range being limited to specific ecological niches.
Agronomic Management for Optimum Yield in Rice Production
Good land preparation is a prerequisite for profitable rice growing. The permanent field is prepared by clearing, tilling and pudding the soil for proper rooting of the plant and bonds are created around the yield to retain water (WARDA, 2002).
Transplanting is the major method of growing rice. When rice seedlings are transplanted at the right time in terms of age, tillering and growth proceed normally (Mobasser et al; 2007). Older seedling with the exception of root dry weight, do not perform well compared top young seedlings in all physiological and morphological aspects. Studies revealed that seedlings, particularly young ones stand well in shallow water and can cope with high temperature. Tillering dynamics of rice plant greatly depend on the age of seedling at transplanting (Pasuquin et al; 2008).
Stoop, et al (2002) indicated that young seedlings below 10 days of age are transplanted in systems of rice intensification (SRI), which produce higher number of tillers than conventional rice production systems, and contributes to higher grain yield (Krishna et al; 2008). However, Pasuquin et al (2001) observed absence of transplanting shock with 7-21 day old seedlings. Conventionally, seedlings are transplanted 3 weeks (21 days) after seeding (Shahzad, 2009).
This is a technique of replanting a dead plant where seedling did not survive. The hills where seedling or transplants did not survive are gap-filled between 7-15 days after transplanting, using the remaining seedlings from the nursery (WARDA, 2002)
Water management is critical during panicle development. If plants are subjected to moist stress during panicle development, irreversible damage with less of yield may occur. During this period, vegetative parts are fully developed and use water at a high rate by the process of transpiration (WARDA 2002).
Satisfactory management of rice weeds can be achieved by the adoption of conservation at minimum tillage farming. Critical period for weed control is in the first 40 days of sowing. Integrated weed management method that includes clean seeds, good land preparation, early sowing, appropriate spacing, manual weeding at 3 and 6 weeks after planting/transplanting and herbicide application should be adopted (Bright, et al; 2000).
Fertilizer should not be applied to weedy field or when heavy rainfall is imminent. Split application should be done. Basal application at 1-2 weeks after planting/transplanting and top-dressing at panicle initiation or 6-7 weeks after planting transplanting is recommended.
Babu et al. (2001) confirmed increased test weight due to application of organic manure, (farm yard manure, green manure) as compared to control. The significant response might be due to better availability of photosynthates from source to sink resulting in increased grain test weight. Again, (Jogioy et al; 2006) reported that application of animal manure plus chemical fertilizer gave the highest chlorophyll. However, Jothityangkoon et al (2005) found that the application of enhancing agent for fertilizer use efficiency did not affect growth and yield of rice production.
The organic manure application with chemical fertilizers increased the yield more than chemical fertilizers because of increased nitrogen use efficiency of rice. The application had no effect on growth and yield of rice (Xu et al, 2008).
Water is the most important factor in rice production. If affects the physical characteristics of the rice plant, nutrient status of the soil, the nature and extent of weed growth and various cultural practices. Rice plant height appears to be directly related to the depth of water. If the water is too deep at transplanting, the seedlings will be tall and healthy. Fewer tillers develop when the water is deeper. Zhong et al (2001) found that the productive tiller percentage was significantly and negatively correlated with maximum tiller number per unit area.
This is the process of cutting and collecting of mature rice panicles when the rice ripens into a golden brown colour. The rice must not be left to get too dry before harvesting because the panicles will shatter before or during harvesting. Harvesting should not be delayed after maturity. Proper timing is about 1 month after crop heading when 80% of the grains on the panicle has turned to straw colour. Harvest and dry harvested materials for 4 days before threshing. It is necessary to prevent the grains from being in contact with sand during harvesting and threshing to eliminate stones (Ram et al, 2000).
MATERIAL AND METHODS
The field experiment was conducted under lowland conditions at Biotechnology Research and Development Center Farm of Ebonyi State University Abakaliki in South East Nigeria. The area lies at latitude 600 N and longitude 080 65 OE, and an altitude of 91.44m above sea level in the derived savannah of south-eastern agro ecological zone of Nigeria. The mean annual rainfall ranges from 1700 mm-2000 mm. The minimum and maximum temperatures are 27oC and 31oC, respectively. The relative humidity at dry season and rainy season ranges between 65-75%.
The trial was a 3 x 3 factorial experiment in a Randomized Complete Block Design (RCBD) with 3 replications. The factors include 3 varieties of rice, FARO 44, FARO 52 and IWA 8 (Factor A), 3 fertilizer types: organic, inorganic, and no fertilizer at all (Factor B).
The experimental field was laid out in into three blocks (replicates) and each replication consisted of nine (9) plots given a total of 27 experimental plots. Each plot measured 2m x 1m with 0.5m within row and 1m between row. The fertilizer treatment was applied at three levels as 200kg/ha of organic manure pellet, 300kg/ha of inorganic fertilizer and also 0 kg/ha signifying no fertilization at all.
Field preparation and Planting
The site was properly cleared, ploughed and harrowed manually with cutlass and hoe. The dried seeds were sown directly in a shallow hole at the rate of four to six seeds per hole with a spacing of 20 cm x 20 cm apart.
20 days after seedling emergence, thinning was done to retain three plants per hill. The plot size was 2 m x 1 m and contained a total of 50 plants per plot.
Thinning and supplying
After fifteen days of planting, rice was thinned to two or three plants per hill and the seedlings were used together with small nursery that was done outside the field to supply some planted hills that failed to germinate.
Weed was controlled manually to keep the site free from weed competition. This was done three times before it was ready for harvest. The first one was done 3 weeks after planting while the second and third was done at 3 weeks interval.
A well compounded organic manure (pellet) and inorganic material of 20:10:10 N.P.K was applied at the recommended rate of 200 kg/ha and 300kg, respectively, after three weeks of planting. Second fertilizer application was done after three weeks to boost the vegetative growth and panicle development. These were done by broadcasting method.
Application of Insecticide
Pest like stem borer, mealy bugs, caterpillars’, grasshoppers etc, was controlled with insecticide called Attacks 2.5 E C, while band rodents were controlled by using net to cover the whole field.
Harvesting and Threshing
Harvesting was done when the mature rice panicles ripened into a golden brown colour (when the rice panicle was not too dry to avoid shattering). It was harvested manually by using kitchen knife.
Threshing was done to separate grains from panicle before weighing the grains.
Data that was collected included:
Germination Count: This was collected at 5, 10 and 15 days after seedling in other to calculate the number of days to 50% germination.
Plant Vigor: This was taken at 20 days after seeding thus: 1 (very vigorous), 3 (vigorous) and 5 (less vigorous or dwarf). This was done virtually to note some physio- morphological characteristics of all the genotypes involved in the experi
Number of Productive Tillers (M2): Among yield components, productive tillers are very important because the final yield is mainly a function of the number of panicles bearing tillers per unit area. Number of productive tillers was collected when the plant produced the fifth leaf, at 14 to 22 days after emergence.
Number of Leaves (Leaves/hill): Number of leaves was recorded by counting each leave in a plant per hill for the 5 tagged plants in each plot?
Plant Heights: Plant height was measured from the base of the plant to the tip of the plant using measuring tape or meter rule at 30, 45, and 60 days after planting.
Leaf Area and Leaf Area Index (LAI): Leaf area index is the efficiency of photosynthetic process and on the extent of photosynthetic surface (Lockhart and wise man, 1988). Leaf area index (LAI) was calculated as follow LAI= Total leave area/ ground area.
Flowering: Flowering occurs during and shortly after heading when the florets open, are pollinated and close. The number of days to 50% flowering was recorded in each plot.
Length of Panicle: The length of panicle was measured with meter rule at the each tagged Plant.
Number of Seeds per Panicle: The number of seed per panicle was count and recoded for each 5 tagged plant.
Grain Weight (G): The weight of grains was taken and recorded (100 or 1000 seed weight?).
The statistical analysis of data collected was based on the Procedure for a Randomized Complete Block Design (RCBD) for factorial experiment as outline by Steel and Torrie, 1980.
The separation of treatment means for significant effect was done using F-LSD as described by Obi (1986) and Okporie (2006).
Number of Productive Tillers (M-2)
Among yield component, productive tillers are very important because the final yield is mainly a function of the number of panicles bearing tillers per unit area. The experiment recorded significant difference among the fertilizers applied for number of productive tiller with inorganic fertilizer 300 kgha producing the highest number of productive tillers Ashraf et al. (1999) stated that transplanting of 2 and 3 seedling hill-1 of 35 day old nursery gave more promising results in term of more productive tillers per unit area, while, Zhong et al. (2001) found that the productive tiller percentage was significantly and negatively correlated with maximum tiller number per unit area. This supports the result of this experiment.
Number of Leaves/Hill
Significant difference was observed in number of leaves/hill with inorganic fertilizer at 300kgha recording the highest value. Although a non-significant difference was observed among the varieties, FARO 52 obtained the highest number of leaves/hill This report is in agreement with the work of Baloch et al., (2002) which stated that wider spacing had linearly increasing effect on the performance of individual plants. Plant grown with wider spacing had more area of land around them to draw nutrient and had more solar radiation to absorb for better photosynthesis process and hence perform better as individual plant.
Inorganic fertilizer at 300kgha produced the highest plant height (FARO 52. The lowest and shorted variety was recorded for IWA 8 when 0 kgha (plant height. This report is in agreement with the work of (Ashrafwzzaman, et al., 2009) who reported that plant height is mostly governed by the genetic makeup of cultivars, although environmental factors also influence it. Mohammad et al., (2002) reported significant differences among varieties for plant height in which the varieties below 100cm where resistant to lodging.
Days to 50% Flowering
There were variations in the number days to 50% flowering of the various rice lines as influenced by fertilizer treatment. This is similar to the report of Bina et al., (2004) who said that significant differences in the number of days required to 50% flowering existed between different rice varieties. Delay in flowering could be attributed to water stress during the vegetative growth stage and is negatively associated with grain yield (Kurma et al., 2006).
Panicle length showed significant differences among fertilizer treatment and non- significant differences among varieties studied. This is contrary to the results of Shirirame and Mulely (2003) who reported that panicle length had no significant difference among fertilizer treatment in their study. On the other hand Sharma (2002) worked with fine grain rice and reported that there was non- significant difference among varieties in panicle length, similar to the result obtained in this study.
Number of Seeds per Panicle
A significant influence of the fertilizer treatments and varieties studied was observed for number of seeds per panicle. The highest number of seeds per panicle was obtained for inorganic fertilizer 300kgha, the lowest number of seeds per panicle was obtained for 0 kgha (102.6). Tiwari et al., (2002) reported increase in grain yield due to application of organic manure, while Ram et al., (2000) reported significant increase in number of seeds per panicle in rice due to integrated use of FYM, press mud, water hyacinth along with fertilizer N.
The result of this experiment showed that application of inorganic fertilizer with the rate of 300kg per plot showed the greater performance of vegetative growth than organic manure 200 kgha. This trend is repeated for most of the traits.
The limitations of this work lies in the fact that equivalent levels of both organic and inorganic fertilizers were not worked out and used. Several levels of both organic and inorganic fertilizers should have been evaluated alongside the control in order to identify a more appropriate one for rice cultivation. Future researches should therefore tackle these aspects.
Rice – Effect Of Organic And Inorganic Fertilizer On The Growth And Yield Of Three Lowland Rice Varieties