New Delhi, July 3 -- Tomato prices are rising again after excessive heat damaged the summer crop in key producing regions, tightening supplies during the lean season. Experts expect prices to remain firm through July and August as delayed kharif sowing is likely to postpone fresh arrivals. Retail tomato prices have risen 16% over the past month and 23% from a year earlier, according to data from the consumer affairs ministry. The average retail price stood at Rs.42.5 per kg on June 30. The pressure is also visible in wholesale markets, where prices are up 18% month-on-month and 28% year-on-year, indicating that higher procurement costs could continue to push up retail prices in the coming weeks. "Prices in major centres are up between 30% a...