Muhammad Asad Hameeda, Khurram Shehzadb, Hafiz Muhammad Bilalc*, Mohammad Aneeqd, Nawal Saeede
aLand Resources Research Institute, National Agricultural Research Center, Islamabad, PAKISTAN
bCollege of Resources & Environment, Huazhong Agricultural University, Wuhan, CHINA
cCollege of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, CHINA
dDepartment of Plant Protection, Selcuk University, Konya TURKEY
eCollege of Food Science and Technology, Huazhong Agricultural University, Wuhan, CHINA
*Corresponding author: [email protected]
Sunflower (Helianthus Annuus L.) is the 4th most cultivated oil seed crop worldwide by area. In recent decades, it was introduced as an oil seed crop in Pakistan but its cultivation and yield is fluctuating due to various production and socio-economic constraints. Sunflower is one of the most commonly grown oilseed species with a worldwide production of grain and oil over 28.5×106 and 10.5×106 Mg respectively, and it is grown around 22.6×106 hectares with a seed yield of 1.3 tons/ha. Sunflower seeds have a great nutritional value, it contains a high amount of oil content (40 to 50%) which is a key source of poly-unsaturated fatty acids such as linoleic acid.
According to the reports of Agricultural statistics of Pakistan 2009-10, the sunflower cultivated area in 2000-01 was 58998 ha and increased to 319743 ha in 2008-09, with the production of 420487 tons and per hectare, the yield was more than 1ton ha-1. Studies on this crop have revealed that there is great potential in the sunflower crop because it can be grown in all types of soils and environmental conditions such as in rain-fed as well as in irrigated farming systems in different agro-ecological zones.
Phosphorous is one of the principal elements in plant nourishment. Lack of Phosphorous availability to plants can significantly reduce plant growth as well as crop yield. Hence, phosphorous based inorganic fertilizers are commonly used in farming lands around the globe to increase soil phosphorous concentration and crop revenues. Phosphorous plays a vital role in numerous metabolic processes in plants such as cell division, production and transport of sugar and starch, the structure of cell wall phosphor-lipids, and root growth. In soils, phosphorous is present as exchangeable, soluble, and precipitated forms, as well as held on the surface of clay minerals. Yet, only a small portion of it is accessible for plant uptake. The results of several studies have indicated that phosphorous concentration in plants is variable throughout different growth phases, and its concentration relies on various factors.
Calcareous soils are commonly present in arid regions of the world where the annual rain fall rate is low, the temperature is too hot, and organic matter content are commonly very low, such as in Pakistan. Phosphorous, when applied to these soils are readily precipitated due to high concentrations of calcium carbonate and pH and becomes unavailable to plants in calcareous soils Therefore, appropriate phosphorous fertilizer management in calcareous soils of arid regions is important for crop production. Therefore using large volumes of chemical fertilizers, the growth and yield of crops can be improved. However, rising costs of these fertilizers and environmental concerns linked to their use have led to the development of alternative strategies.
The use of beneficial soil microorganisms and, carbon-based organic materials such as PSB and biochar could decrease the amount of fertilizer input by enhancing the efficiency of nutrient availability and other plant growth promoting activities.
A diverse gathering of soil microbes is involved in solubilizing insoluble P complexes and enabling plants to easily absorb P. Many kinds of soil bacteria such as Bacillus, Pseudomonas, Rhizobium, and Enterobacter have the skill to change the insoluble form of phosphorous in the soil into soluble form through releasing organic acids such as formic, propionic, fumaric, acetic, and succinic acids. The usage of beneficial microorganisms (bio-fertilizers) like phosphate solubilizing bacteria (PSB) as inoculants with the seed rises the phosphorous acquisition because the beneficial microorganisms release organic acids which condense soil pH. These acids reduce the pH and carry the dissolution of fixed forms of phosphate. These beneficial germs are significant not only for the decline in the usage of inorganic fertilizers but also for environment friendly and also increased crop productivity.
Biochar is a porous solid, carbon-rich material prepared by chemical-thermal alteration of biomass in an environment with a shortage or lack of oxygen. Research has exposed that the addition of biochar to the soil improve soil fertility and agricultural productivity significantly. In addition, it has been shown that biochar has an effect on soil physical such as soil structure, soil texture, pore spaces, and water holding capacity, and chemical properties like pH, cation exchange capacity, and availability of plant nutrients. Biochar application significantly increased the pH and soil available phosphorous concentration to lettuce. Several studies have shown that phosphorous uptake significantly increased with the application of biochar. Therefore, it is possible that biochar application in calcareous soils may improve the availability of phosphorous to plants.
