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CHAPTER III

MATERIALS AND METHODS

The materials used and methods followed during the investigation are given below.

I. Experimental site

The field experiments were conducted at Agronomy farm, College of Agriculture, Dapoli (Plot no. 69 and 70 of ‘C’ block). The topography of the plot was uniform. The site was selected on the basis of suitability of land for cultivation of mid-late variety of hybrid rice during kharif season and mustard during rabi season.

II. Mechanical and chemical composition of the soil

Composite soil sample was collected from 0-30 cm depth with the help of screw auger. The details of the mechanical and chemical composition of the soil and techniques used are given in Table 1. The soil of the experimental plot was loam in texture, acidic in pH and low in organic carbon content. It was medium in available nitrogen and phosphorus, while low in available potassium.

Table 1. Mechanical composition, chemical composition and physical properties of soil.

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III. Climatic conditions

Agronomy Farm, College of Agriculture, Dapoli is located in the subtropical region at 17.1⁰ North latitude and 73.1⁰ East longitude, having elevation of about 250 m above mean sea level. The climate is characterized by warm and humid days and is very much favourable to crops like hybrid rice and mustard. The different climatic parameters recorded at the meteorological observatory, Agronomy Farm, College of Agriculture, Dapoli during period of experimentation are presented in Table 2 and graphically depicted in Fig. 1.

Table 2. Meteorological data for kharif and rabi seasons during the crop growth period (2000-2002).

The data reveal that mean annual rainfall was 4648.9 mm and 2412.2 mm that was received in 97 and 125 rainy days in 2000-2001 and 2001-2002, respectively. The relative humidity was in the range of 62.60 to 94.45% and 66.75 to 90.55% in 2000-2001 and 2001-2002, respectively. The maximum temperature during crop growing seasons were in the range of 27.2 to 32.7⁰C and minimum temperature of 11.3 to 22.0⁰C during 2000-2001 and in 2001-2002, it was in the range of 26.3 to 33.4⁰C for maximum and 11.7 to 23.2⁰C for minimum. Thus, the climatic conditions were favorable for growth of kharif hybrid rice and rabi mustard during both the years.

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IV. Cropping history of the plot

The details of the crops grown in the experimental plot for the last five years are presented in Table 3.

Table 3. Cropping history of the experimental plot.

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V. Details of kharif experiment

The experiment was carried out during kharif season of 2000 and 2001. The hybrid rice cultivar ‘Sahyadri’ was used for investigation. The experiment was laid out in Randomized Block design in kharif season with three replications. The plan of layout and details of treatments along with their symbols used are given in Fig. 2.

1. Field operations

The schedule of field operations carried out during conduct of experiment is given in Appendix I for both the years.

2. Raising of seedlings on nursery bed

The soil was ploughed twice by tractor and brought under fine tilth. The raised beds of 10 m length, 1 m breadth and 10 cm height were prepared. A good quality FYM was spread over the beds. Urea was applied @ 1 kg 100 m^-2 at the time of sowing. The seeds were treated with Thiram @ 2.5 g kg^-1 of seed. The treated seed was sown in lines 10 cm apart at 2-3 cm depth. Germination started from third day and completed by the fifth day. Top dressing with urea @ 1 kg 100 m^-2 was undertaken 15 DAS. The plant protection and weed control measures were undertaken in nursery as and when needed.

3. Preparatory tillage

The soil was thoroughly puddled with the help of tractor drawn puddler. The field was leveled with the help of wooden leveler.

4. Application of organic manures and fertilizers

Gliricidia leaves were incorporated in the respective plot two days before transplanting. 50% N through urea, full dose of phosphorus and potassium through Single super phosphate and Muriate of potash, respectively were applied as per treatments by broadcasting at the time of transplanting. The remaining 50% N was applied in two equal splits i.e. at maximum tillering (30 DAT) and panicle initiation stage (65 DAT) according to the treatments. UB-DAP were applied a week after transplanting of hybrid rice as per treatments.

5. Transplanting of seedlings

Twenty eight days old seedlings were transplanted on 8^th July, 2000 and 13^th July, 2001 at the spacing of 20×15 cm using only one seedling per hill.

6. Gap filling

Gap filling was completed within eight days after transplanting to maintain the uniform plant population.

7. Weed control measures

Hand weeding and hoeing was done twice to keep the experimental crop weed free.

8. Plant protection measures

The crop was free from pests and diseases. As a preventive measure, the spraying of Endosulfan and Cypermethrin was taken against different sucking insects at 45 DAT and 60 DAT. The poison baiting with Endosulfan was undertaken in crab burrows during initial days of crop growth after transplanting to control crabs.

9. Harvesting and threshing

The crop was harvested, when grains were fully matured and the straw turned yellow. The plants were cut close to the ground and kept in respective plots for sun drying. Threshing was done plot wise. Grains were separated from chaff by winnowing. Grain and straw yields were recorded by weighing.

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VI. Biometric observations in hybrid rice

The details of various biometric and other observations recorded during the course of study are mentioned in Table 4. Five hills from each net plot were randomly selected for recording biometric observations. The selected hills were labeled with proper notations.

Table 4. Details of biometric and other observations in hybrid rice.

1. Plant population

Plant population count 20 DAT and at harvest for each treatment was recorded from each plot.

2. Height of plant (cm)

Height of hybrid rice plant was measured from the base of the plant i.e. ground level up to the tip of fully opened leaf at an interval of 30 days.

3. Number of tillers per hill

The total number of tillers produced per hill was counted periodically from five hills and average of the five hills was recorded.

4. Number of functional leaves per hill

The number of functional leaves produced by each hill was counted periodically from the five hills and average was recorded.

5. Dry matter accumulation (g) per hill

Four hills from the gross plot were sampled. They were uprooted, cleaned and roots were removed. The plants were kept in brown paper bags for air drying. The samples were oven dried at 65 to 70⁰C. Dry weights were recorded and the average was worked out.

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VII. Post harvest studies in hybrid rice

1. Number of panicles per hill

The number of panicles per hill was counted from five hills selected for biometric observations and average was worked out.

2. Length of panicle (cm)

Length of five panicles from each net plot was measured from the base of the whorl up to the tip of the panicle and average length of panicle was worked out.

3. Number of filled grains per panicle

The number of filled grains was counted from the five panicles selected randomly from each net plot and average number was worked out.

4. Number of unfilled grains per panicle

The number of unfilled grains was counted from the five panicles selected randomly from each net plot and average number was worked out.

5. Weight of filled grains per panicle (g)

The weight of filled grains was recorded from the five panicles used for measuring length and counting number of filled grains per panicle and average weight of grain per panicle was worked out.

6. Thousand grain weight (g)

A representative sample of grains was taken from the total produce of each plot and thousand grains were counted and weight was recorded as per treatments.

6. Grain yield (q ha^-1)

The grain yield obtained after threshing the produce from each net plot was sun dried for about four days and final weight was recorded in kg per plot, which was then converted into q ha^-1.

7. Straw yield (q ha^-1)

The straw yield was obtained by weighing air dried straw, which remained after threshing from each net plot. The figures were converted on hectare basis.

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VIII. Details of rabi experiment

The experiment was carried out during rabi season of 2000-2001 and 2001-2002. The experimental layout used for kharif hybrid rice was utilized for rabi experiment by dividing the experimental units into three subplots according to Split Plot Design, to study the residual effect of preceding hybrid rice on the succeeding mustard. The plan of layout and treatment details along with symbols used is given in Fig. 2.

1. Field operations

The schedule of field operations for mustard carried out during the crop growth season is given in Appendix II for both the years.

2. Seed material

Mustard variety ‘Varuna’ was used in the present investigation. The seed was obtained from the Department of Agronomy, College of Agriculture, Dapoli and was tested for germination percentage. The germination was 98-99%, which resulted in good plant stand in the field.

3. Sowing

The seeds were sown in line to a depth of about 3 to 4 cm in the soil with the help of manual labors and covered properly with soil. The spacing of 45×15 cm with a single healthy seedling per hill was maintained in the plot.

4. Application of fertilizers

The fertilizers were applied as per treatments. The basal dose of 45 kg P₂O₅ ha^-1 through single super phosphate and 45 kg K₂O ha^-1 through muriate of potash was applied at the time of sowing. Fertilizer nitrogen was applied in 3 splits i.e. 50% at the time of sowing, 25% one month after sowing and 25% two months after sowing as per treatments through urea.

5. Plant protection measures

Plant protection measures against mustard aphids (Myzus persicae S.) and mustard saw fly (Athalis proxima Klang.) were undertaken by alternate sprays with Dimecron and Endosulphan at concentrations of 0.04 and 0.05%, respectively as and when needed.

6. Harvesting and threshing

The crop was harvested, when siliquae matured and turned yellowish brown in colour. One line from all the sides of the plots was removed to eliminate the border effect. The plants were cut close to the ground and transferred to threshing floor. Threshing was done plot wise. Grains were separated from siliquae by beating with sticks and cleaned. Grain and straw yields were recorded by weighing.

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IX. Biometric observations in mustard

The details of various biometric and other observation recorded during the course of study are mentioned in Table 5. Five plants from each net plot were randomly selected for recording biometric observations. The selected plants were labeled with proper notations.

Table 5. Details of biometric and other observations in mustard.

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1. Plant population

Plant population count 20 DAT and at harvest for each treatment was recorded from net plot area.

2. Height of plant (cm)

Height of plant (cm) was measured from the base of the plant i.e. from ground level up to the tip of the plant at an interval of 30 days.

3. Number of branches per plants

The total number of branches produced per plant was counted periodically from five plants and average of the five plants was recorded.

4. Number of functional leaves per plants

The number of functional leaves produced by plant was counted periodically from the five plants and average was recorded.

5. Dry matter accumulation (g) per plants

Four plants from the gross plot were sampled. They were uprooted, cleaned and roots were removed. The plants were kept in brown paper bags for air drying. The samples were oven dried at 65 to 70⁰C. Dry weights were recorded and the average was worked out.

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X. Post harvest studies in mustard

1. Number of siliquae per plant

The number of siliquae per plant was counted from five plants randomly selected for biometric observations and average was worked out.

2. Length of siliquae (cm)

Length of five randomly selected siliquae from each net plot was measured and average length of siliquae was worked out.

3. Number of grains per siliqua

The number of grains was counted from the five siliquae randomly selected for measuring length from each net plot and average number was worked out.

4. Weight of siliquae (g) per plant

The weight of siliquae per plant (g) was taken from the five siliquae selected for measuring length from each net plot and average number was worked out.

5. Thousand grain weight (g)

A representative sample of grains was taken from the total produce of each plot and thousand grains were counted and weight was recorded as per treatments.

6. Grain yield (q ha^-1)

The grain yield obtained after threshing the produce from each net plot was sun dried for about 4 to 5 days and weight was recorded in kg per plot, which was then converted into q ha^-1.

7. Stover yield (q ha^-1)

The stover yield was obtained by weighing air dried stover, which remained after threshing from each net plot. The figures were converted on hectare basis.

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XI. Chemical studies

1. Plant analysis

The sample plants were harvested and used for chemical analysis of grain, straw and stover. The dried sample of grain, straw and stover were powdered separately and about 20 g of representative samples from each treatment was stored in a brown paper bag, suitably labeled and used for estimation. The content of nutrient was multiplied by respective yield of grain, straw and stover to work out the total nutrient removed by crop in kg ha^-1. The total nitrogen was determined by Modified Kjeldahl method (A.O.A.C., 1955). Protein content was estimated by multiplying nitrogen content by 6.25. Total phosphorus content in plant was determined by adopting vanadomolybdate yellow color method (Jackson, 1973) and potassium content was estimated by using flame photometer by adopting technique given by Chopra and Kanwar (1978). Oil content was estimated by specific gravity method (Mishra, 1998).

2. Soil analysis

Soil analysis was carried out from the samples drawn at harvest for available NPK. The samples were air dried and properly sieved. Soil physical properties were determined after harvest of each crop. The bulk density and water holding capacity was determined by Keen Rackzowski method.

XII. Statistical analysis and interpretation of data

Experimental data was analyzed by applying standard method known as ‘Analysis of variance’ as applicable in Randomized Block design in kharif season and Split Plot design in rabi season as described by Panse and Sukhatme (1985). The significance of the treatments was tested by variance ratio test (‘F’ test) and critical difference (C.D.) at 5% level of probability was worked out for comparison between treatments. The grain and straw yields of hybrid rice and grain and stover yields of mustard were pooled over for two seasons. Tabular and graphical representations of the data are presented at appropriate places.

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XIII. Hybrid rice yield equivalent

The hybrid rice yield equivalent was calculated using the following formula (Reddy and Reddi, 1997).

XIV. Economics of treatments

The gross income per hectare was calculated on the basis of price of grain, straw and stover yields. The prevailing market prices for grain and straw were considered. The cost of cultivation of crop under individual treatment was worked out by taking into account the cost up to Cost C.

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