Plant Water Relations and Seedling Growth of Three Pistachio Cultivars as Influenced by Irrigation Frequency and Applied Potassium

Abstract

Despite the economic importance of pistachio (Pistasia vera L.) crop, very little information is available on its water needs and nutrient requirements. Therefore, the effects of three irrigation frequencies (1, 3, and 7 d) and five potassium (K) levels (0, 75, 150, 225, and 300 mg kg^{− 1}) on the plant water relations and growth of three pistachio cultivars (‘Badami,’ ‘Ghazvini,’ and ‘Sarakhs’) were studied in a greenhouse experiment. After 30 weeks, the dry weights of leaves, stems, and roots were measured and the total leaf area determined together with the number of leaves per pot and stem height. The effect of water frequency and K application on the leaf water potential, osmotic potential, and turgor potential was studied. Water frequency decreased all of the above growth parameters. Shoot dry weights were reduced by 50% and 68% for ‘Badami,’ 42% and 66% for ‘Ghazvini,’ and 26% and 46% for ‘Sarakhs’ at the three and seven-day irrigation intervals, respectively. Root dry weights were significantly reduced by 27% and 47% for ‘Badami,’ 18% and 48% for ‘Ghazvini,’ and 10% and 28% for ‘Sarakhs’ at the three and seven-day irrigation intervals, respectively. Leaf water potential, and turgor potential were unexpectedly increased by increase in water frequency. However, water frequency decreased leaf osmotic potential. The K application had no significant effect on the leaf water potential, osmotic potential, and turgor potential. It seems that NH₄OAc-extractable K (70 mg kg^{− 1}) was probably sufficient for optimum seedling growth of pistachio. Furthermore, ‘Sarakhs’ proved to be the cultivar most tolerant to drought stress in the present study.

Keywords:

• water stress
• plant water status
• leaf area
• leaf water potential
• osmotic
• potential
• turgor potential

ACKNOWLEDGMENTS

We wish to thank Shiraz University Research Council for its approval and for providing financial support.

Notes

*One Mpa is equal to 10 bars.