Effect of Foliar Spraying with Nano and Natural Materials under Water Stress Conditions on Cotton Leaves Chemical Composition

Two field experiments were conducted on a clay soil at El-Gemmeiza Agricultural Research Station, , Egypt during growing 2015 and 2016 seasons, to find out the proper irrigation interval and the effect of Nano and natural materials in reducing the negative effect of water stress on cotton leaves chemical composition of the Egyptian cotton cultivar Giza 86 through study the effect of three Nano-materials treatments (without, 7.5g/L lithovit and 1 cm3/L amino mineral) and three natural materials treatments (without, 200 ppm salicylic acid and 5cm3/L humic acid) under three irrigation intervals (every14, 21 and 28 days) as well as their interactions. Each experiment contained three separate experiments represented the three irrigation intervals; i.e. every 14, 21 and 28 days. Also, the combined analysis between the three experiments was done. The two other factors distributed in each experiment in a strip plot design with four replicates, where the horizontal plots were assigned to the foliar of Nano-materials and the vertical plots contained natural materials treatments. Results showed that: The highest percentages of N, P and K in leaves were obtained from irrigation interval of 21 days followed by irrigation interval of 28 days. Also, irrigation intervals exhibited significant differences in leaves concentrations of photosynthetic pigments i.e. chlorophyll a and total chlorophyll, total carbohydrates and total sugars in both seasons and chlorophyll b and carotenoids in the 2nd season only, under irrigation interval of 21 days. The minimum values of leaves proline concentration, peroxidase and phenoloxidase activity in cotton leaves were obtained from irrigated every 21 days which induced favorable conditions and reduces water stress effect.  Foliar CO2 as a Nano fertilizer (in the form of lithovit) three times at a rate of 7.5g/L significantly increased percentage of N, P and K in leaves and leaves concentrations of photosynthetic pigments such as chlorophyll a, chlorophyll b, total chlorophyll and carotenoids, leaves total carbohydrates and total sugars contents in both seasons. Also, it significantly decreased leaves proline content, peroxidase and phenoloxidase activity which indicates favorable conditions and reduces water stress effect; however untreated plants recorded the highest values. Foliar feeding with 5 cm3/L humic acid three times significantly increased percentage of N, P and K in leaves, values of leaves concentrations of photosynthetic pigments i.e. chlorophyll a, chlorophyll b, total chlorophyll and carotenoids, total carbohydrates and total sugars followed by using salicylic acid as foliar spraying at a rate of 200 ppm and the least values were obtained from untreated plants (without natural materials application) in both seasons. In contrary, applying 5 cm3/L humic acid results recorded the lowest values of proline content, peroxidase and phenoloxidase activity in leaves in both seasons followed by applying salicylic acid at a rate of 200 ppm.  Plants irrigated every 21 days which received CO2 as a Nano fertilizer at a rate of 7.5 g/L in combination with 5 cm3/L humic acid led to a significant increase in P, K, total sugars and total carbohydrates concentrations in leaves compared to the other interaction treatments; however, cotton plants irrigated every 14 days without application with Nano or natural treatments produced the lowest concentrations. Also, plants irrigated every 21 days which received CO2 as a Nano fertilizer at a rate of 7.5 g/L in combination with 5 cm3/L humic acid gave the lowest values of proline content, peroxidase and phenoloxidase activity in cotton leaves in the first season, which induced proper conditions for plant growth and reflect on reduce water stress effect. It could be concluding the irrigation cotton plants every 21 days in combination with foliar CO2 as a Nano fertilizer (in the form of lithovit) at a rate of 7.5g/L and foliar feeding spraying with 5 cm3/L humic acid three times (at the squaring stage, flowering initiation and at the top of flowering) to overcome the water shortage at the end of water sources (canals) as well as when water scarcity becomes wide spread, where this combination is the best treatment for good leaves chemical composition under the conditions of El-Gemmeiza location.