Leaf analysis status of Nitrogen, Phosphorus and Potassium in acid lime (Citrus aurantifolia SWINGLE) through induction of water stress and application of growth regulators
Abstract
Application of growth regulators and induction of water stress at different growth stages is known to improve yield in many of the fruit crops. An experiment was carried out at Horticultural College and Research Institute, Periyakulam during the year 2006-2008 on five year old trees of acid lime cv. PKM 1 in the main and off seasons of a year. The trees were subjected to soil water stress conditions at two levels (30 days and 45 days) along with spraying of growth regulators viz., (CCC 500 ppm, ascorbic acid 50 ppm and gibberellic acid (GA3)10 ppm. Soil water stress was taken as one factor and growth regulator was another executed following factorial randomized block design. In general, nitrogen content of leaves was more in main season than off season. Three way interaction between stress, growth regulators and stages of tree growth revealed that the combination S1C2L1 (water stress for 30 days + foliar spraying of ascorbic acid 50 ppm concentration at vegetative stage) registered the highest nitrogen content (2.97 and 2.92 per cent) in the main season of the year 2006 – 07 and 2007 – 08. The phosphorus and potassium content of leaves of acid lime also found significant irrespective of seasons. The combination S1C2 (30 days water stress along with foliar application of ascorbic acid 50 ppm concentration) recorded the highest phosphorus content in the main (0.19 and 0.18 per cent) and off (0.19 and 0.16 per cent) season during the year 2007 - 08 and 2006 - 07 respectively. The interaction between stress, growth regulators and stages of tree growth showed that the combination S1C2L1 recorded the highest potassium content (2.37 and 2.35 per cent) in the main and off season of the year 2006 – 07 and 2007 – 08. It was followed in the combinations S2C3L1 (2.30 and 2.27 per cent) and S1C1L1 (2.13 and 2.12 per cent) in the year 2006 - 07 and 2007 - 08 respectively.
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Introduction
Acid lime is the third most important fruit crops in citrus sp. It plays an important position in daily life of human beings for reliving thirsty during summer period and contributes an important place in rituals and festivals. Though its production is confined to homestead garden in parts of Tamilnadu in India, it is considered for the vast medicinal properties. Plant growth regulators are found to be widely used in many of the fruit crops for modifying plant growth and development.
Conclusion
Very few studies interpreted on water relations in fruit trees and nutrient mobility under water stress conditions. The relationship of these complex relations to the responses of stomata, photosynthesis, transpiration and respiration rates are complex to evaluate. Movement of mineral nutrients through the soil to the plant root is dependent on both mass flow of soil solution driven by water uptake by the plant root and the slow process of diffusion (Lakso, 1985).
High soil water stress restricted the movement of nutrients to the roots both by increased difficulty of movement along the soil particles and the reduction of mass flow when stomatal closure restricts transpiration. The increased nutrient content at low water stress of the present study are in line with the reports of Tromp (1980) and Levin et al (1980) show increased Ca/K ratios with soil moisture stress while leaf content of nitrogen was not greatly affected.