Rosa centifolia is a nontraditional high value crop in Pakistan. Its demand and area is increasing every year because it can produce flowers throughout the year including summer season and used for extraction of essential oil, making rose water, jam and eye drops. The increasing demand has built pressure on farmers and researches to find new ways for increasing its good quality yield. Previously work has done in the University of Agriculture, Faisalabad, Pakistan, to develop a protocol for in vitro propagation and standardization of concentrations of plant growth regulators for rapid and healthy growth of R. centifolia. We have also performed another successful experiment to increase its better growth and flower yield. In this experiment different types of mulching materials were used to find most effective mulching material, which can conserve soil moisture, control weeds and improves the production and quality of centifolia roses.
Mulches are materials placed around the plants to cover the soil, which conserves soil moisture, reduces light to reach soil thus minimizes evaporation, regulates soil temperature, suppresses weed growth, and positively affects the plant growth and yield. Various mulching materials are used for different crops depending on their availability, cost appearance and effect on soil like combustion, decomposition and chemical reactions. There are two types of mulches, organic and inorganic. Organic mulches are of plants origin temporary, decomposed with time and wetted by rain and dew, which affects their usefulness. Organic mulches include grass clipping, which are collected from the lawn after mowing and used as mulch in elsewhere.
Grass clippings can be used as dry to mediate the quick decomposition and unnecessary heat production. Peat moss is effective long lasting organic mulch, which form dense crust on soil surface to reduce water soaking. Straw are light in weight easily available organic mulches. Barks of trees with different sizes and colors are also used as organic mulches. Leaves of different plants can also be used as organic mulched, which can be collected during autumn season from deciduous plants and used in winter to protect plant from winter frost. Black and white polythenes are mostly used as inorganic mulching material. These are mostly used for long period of time and conserves soil moisture, temperature and control weed growth. Polythenes trap sunlight and increases temperature for better growth of plants. In Pakistan most commonly available mulching materials are plastic mulch, saw dust, grass clippings, rice straw and these were also used in this study. The depth of grass clippings and rice straw was 2 inches, 1.5 inches saw dust and thickness of plastic sheet was 0.4-mm. After mulch application regular monitoring was done once a week and all agronomic practices were equally done under unfertilized conditions. Data of different parameters was collected after 30 and 60 days of mulch application. Soil samples were collected at 0-15cm and 15-30cm depth with the help of Augar and dried in oven to study its different physical and chemical properties. Soil temperature was measured at 20 cm depth after 30 and 60 days. Numbers of weeds were counted from per square of field area and weeds dry and fresh weights were also calculated.
According to our results, maximum soil moisture conservation (important during higher temperature of summer months) and relatively lower temperature was observed in plastic mulch. Plastic mulch was also found most effective for decreasing number of weeds, weed dry and fresh weight both after 30 and 60 days. Numbers of branches, number of leaves, root length, root fresh and dry weight were recorded maximum in plants grown under plastic mulch. In case of flowering plastic mulch was again observed better than others by producing maximum number of flower per plant, number petals per flower and flower size. Our findings have proved that by using plastic mulch in the field of rose plants, we can grow healthy plants with higher flower yield under effective soil conditions and limiting weed growth.
Our research has provided an effective and easy to use method to farmers for increasing the yield of Rosa centifolia as higher yield of flowers is a key to start a successful business of essential oil extraction of R. centifolia. Some companies are trying to start this business but main hurdle is the continuous supply of huge amount of flowers because higher numbers of flowers are required to extract a small amount of essential oil of R. centifolia.
The writer is associated with the Institute of Horticultural Sciences, University of Agriculture Faisalabad, Pakistan. He can be reached at <email@example.com>