Effect of Farm Yard Manure and Planting Densities on Growth, Yield and Quality of Okra under Natural Farming

Among rapidly consumed vegetables, okra is one popular green crop in Pakistan grown during spring summer season. As the plant life cycle falls in short duration crops, proper plant nutrition for high yielding varieties influence greatly on the production and quality traits of okra. To regulate high quality fruiting and sufficient picking adequate minerals are essential for potential fruit yield required by okra plant. Trend of intense cultivation of agricultural crops resulted in the degradation of fertile land. Recently awareness of organic farming and sustainable agriculture is taking charge over intensive farming systems around the globe. Organic manure is one of the best choices to full fill the needs of plant essential mineral nutrition for enhanced quality and crop yielding, along with properties of improving soil structure, texture and moisture holding capacity (Maheswarappa et al., 1999). Although the amount of micro minerals is reasonable in organic manures as compared to inorganic fertilizers, existence of growth promoting components like hormones and enzymes besides mineral nutrition of plants makes them essential for improvement of soil fertility and productivity (Bhuma, 2001). It is well known fact that farm yard manure (FYM) definitely improves the soil to sustain the nutrient status and water holding capacity.


INTRODUCTION
Among rapidly consumed vegetables, okra is one popular green crop in Pakistan grown during spring summer season. As the plant life cycle falls in short duration crops, proper plant nutrition for high yielding varieties influence greatly on the production and quality traits of okra. To regulate high quality fruiting and sufficient picking adequate minerals are essential for potential fruit yield required by okra plant. Trend of intense cultivation of agricultural crops resulted in the degradation of fertile land. Recently awareness of organic farming and sustainable agriculture is taking charge over intensive farming systems around the globe. Organic manure is one of the best choices to full fill the needs of plant essential mineral nutrition for enhanced quality and crop yielding, along with properties of improving soil structure, texture and moisture holding capacity (Maheswarappa et al., 1999). Although the amount of micro minerals is reasonable in organic manures as compared to inorganic fertilizers, existence of growth promoting components like hormones and enzymes besides mineral nutrition of plants makes them essential for improvement of soil fertility and productivity (Bhuma, 2001). It is well known fact that farm yard manure (FYM) definitely improves the soil to sustain the nutrient status and water holding capacity.
The significance of organic manuring in sustainable agriculture is acknowledged well. Gaur et al., 1972 andSubbarao et al., 2001 reported that the application of different organic manures showed a significant increase in plant height and number of fruits plant -1 of chilli (Dileep, 2005). Use of manure from animal and plant origin is most common practice for sustainable and organic farming around the ABSTRACT A field study was conducted to investigate the effect of farm yard manure and planting densities (P x P 10, 15, 20 and 25 cm and R x R 60 cm) under natural farming condition at National Agricultural Research Centre, Islamabad during 2016. The land was incorporated with well rotten farm yard manure (FYM) @ 25 t ha -1 in respective plots (4 x 8 meter) one week before bed preparation and mixed thoroughly in the soil. Seeds of okra (Abelmoschus esculentus L., var. Pusa Green) were sown according to the plan following split plot design with four replications. The crop was allowed to stand till maturity and data on growth traits like plant height, number of pods plant -1 and fresh pod yield (tender young pods) were recorded. The quality characters like crude fiber and moisture percentage were estimated. The mean data were analyzed statistically. Though all the FYM application treatments showed positive effect through growth and yield characters, however, among plant densities, 10 and 15 cm P x P and FYM incorporation @ 25 t ha -1 produced comparable fresh pod yield (11.22 and 10.97 t ha -1 , respectively) which was 25 and 24 % higher than that of without FYM application. Dense populated crop i.e., 10 and 15 cm P x P performed better than rest of planting densities through improved fresh pod yield with comparatively improved quality. Dense populated treatment (P x P 10 cm) and FYM application @ 25 t ha -1 produced better quality fruits with less crude fiber content (9.89 %) and higher moisture content (79.14 %) as compared to without FYM application (10. There is increasing demand for okra because of its importance for delicious cooking in farming systems in many regions. It is a good source of vitamins A, B, and C and iron, calcium, magnesium, phosphorus, and zinc (Asian Vegetable Research Development Council, 1991). The edible part of okra represents 90% of the total weight of fruit with an energy value of 31 kcal per 100 g (De Lannoy, 2001). Keeping in mind these facts, a field experiment was planned to assess the effects of farm yard manure and plant density on yield and quality of okra to determine the optimum population for maximum fruit yield production with better quality attributes of okra var. Pusa green under natural farming environment.

MATERIALS AND METHOD
A Field study was carried out to investigate the effect of farm yard manure (FYM) and planting densities (P x P = 10, 15, 20 and 25 cm and R x R = 60 cm) under natural farming condition during dry season 2016 at National Agricultural Research Centre, Islamabad. The land was incorporated with well rotten farm yard manure (FYM) @ 25 t ha -1 in respective plots (4 x 8 meter) one week before bed preparation and mixed thoroughly in the soil. The experiment was laid out according to split plot design with four replications.
Four seeds of okra (Abelmoschus esculentus L., var. Pusa Green) were directly sown per hole at a depth of 2 cm. After germination, seedlings were thinned to one plant per stand three weeks after planting. Soil samples from (0-30 cm) were collected from 12 different spots in the study area and were composited, air-dried and sieved through a 5 mm sieve and their physical and chemical characteristics were determined before application of treatment (Table 1). The samples were analyzed for soil textural class by hydrometer method (Bouyoucos, 1962). Calcium carbonate was estimated by acid neutralization method and soil organic matter by oxidation with potassium dichromate in sulfuric acid medium under standardized conditions by Walkley and Black procedure (Nelson and Sommers, 1982). Soil pH was determined in water (soil water ratio 1:1). Electrical conductivity (ECe) of the soil suspension was measured using conductivity meter. The P, K and Zn were determined by using AB-DTPA method (Ryan et al., 2001). The crop was allowed to stand till maturity and data on growth characters like plant height, number of fruits plant -1 and yield (tender young pods) were recorded. The quality characters like crude fiber and moisture percentage were estimated. The data thus collected were subjected to statistical analysis and treatment differences were compared by using LSD (Gomez and Gomez, 1984).

RESULTS AND DISCUSSION
All the treatments of FYM application @ 25 t ha -1 along with dens plantation performed significantly in terms of plant height, pods plant -1, pod yield (t ha -1 ), crude fiber contents (%) and moisture contents (%) over non FYM treatments and less dense okra population. Data in Tables  2, 3 and 4 registered statistically significant increase in okra plant growth, yield and quality among all treatments receiving FYM over control treatments (without FYM) and dense population. Results listed in Table 2  Results mentioned in Table 3 indicate that FYM applied treatments produced significantly higher fresh pod yield (11.22 t ha -1 and 10.97 t ha -1 ) of okra plated with 10 and 15 cm planting distances, respectively against 10.97 t ha -1 and 8.81 t ha -1 under same planting densities without FYM application. Comparatively less fresh pod yield under no FYM application might be due to lack of nutrients resulting in reduced growth and yield. The positive effect of FYM on plant growth and yield could be due to the contribution made by manure to fertility status of the soil as the soils were low in organic matter (Table 1).
Manure when decomposed increases both macro and micro nutrients as well as enhances the physico-chemical properties of the soil. This could have led to its high vegetative growth. The significant difference observed in the treatments supplied with FYM as compared to control treatment (without FYM) could be due to the presence of nutrients in the soil which satisfied plants requirements for their health growth. Ajari et al., (2003) reported that in okra production organic manure could increase plant height of crops when compared with other sources of manures or having no manures. Similar findings had also been reported by Premsekhar and Rajashree (2009).
Furthermore, higher and statically significant values of fresh pod length (9.98 cm) and fresh pod weight (45.92 g) of okra under normal plant population (20 × 20 cm) were recorded. On an average, FYM @ 25 t ha -1 application also showed elevated pod length (9.52 cm) and weight of fresh pod (44.65 g pod -1 ), respectively as compared to non FYM treated plots. An opposite trend was observed egarding quality of okra pod fruits in terms of minimum crude fiber (8.87 %) and higher moisture (78.90 %) contents harvested from FYM treated (25 t ha -1 ) under dense populated okra plants (Table 4), as okra pods are found to be the best for cooking and consumption with lesser crude fiber contents. Previous findings of Dileep (2005), Gopalakrishnan (2007) and Tiamiyu et al., (2003) are in line with our results who reported that FYM increased yield and quality of vegetables providing healthy environment and good soil structure and texture.

CONCLUSION
Current experimentation has revealed that farm yard manure (FYM) application @ 25 t ha -1 actively enhanced vegetative growth, increased yield and improved pod quality traits of okra. In addition, dense plantation (P × P 10 cm) improved fresh pod yield per unit area of okra vegetable.For attaining a higher yield and maximum quality of okra FYM @ 25 t ha -1 application and plantation at higher density (P × P 10 cm) could be a very effective protocol for organic and sustainable farming under natural farming.