Effect of irrigation intervals on growth of annual flowers under climatic conditions of South Punjab, Pakistan

Irrigation is one of the major factors to control the growth of annual flowers.Optimization of plant water requirement is important in the current scenario of climate change under limited water availability.Present research was conducted to determine the effect of irrigation intervals on vegetative, reproductive and physiological growth of two annuals, Calendula officinalis L. and Dianthus barbatus L. The seedlings of both annuals were grown in pots containing garden soil as growing media.At first, seedlings were grown for 15 days under regular irrigations.Then four irrigation intervals (T1; daily, T2; 2 days interval, T3; 4 days interval, T4; 6 days interval) were applied.At four days of irrigation intervals, calendula produced maximum plant height (42 cm), stem diameter (5.63 mm), shoot fresh weight (18.40 g), shoot dry weight (4.04 g), root dry weight (1.52 g), root length (21 cm), no. of flower buds (15.67), no. of opened flowers (12.67), flower diameter (35 mm), total antioxidants (79.45) and total phenolic contents (314.58 mg/100g GAE).Dianthus also produced maximum plant height (41 cm), stem diameter (5.85 mm), shoot fresh weight (27.88 g), shoot dry weight (4.86 g), root dry weight (2.76 g), root length (25 cm), no. of flower buds (11.33), no. of opened flowers (6.67), flower diameter (34.90 mm), total antioxidants (86.08) and total phenolic contents (331.87) at four days of irrigation intervals.But increasing irrigation interval from 4 days to 6 days significantly decreased the vegetative and reproductive growth of both the annuals.Hence, it is concluded that irrigation interval after seedling establishment improved the vegetative, reproductive and physiological growth of annual flowers.