new delhi, April 22 -- As summer arrives ahead of schedule in India, warnings of intense heatwaves are raising alarms across the nation's industrial heartlands. Industry executives said soaring temperatures could throttle productivity, risking a slowdown in India's vital manufacturing sector.The weather office has issued heat wave alerts for south Uttar Pradesh, Madhya Pradesh, Rajasthan, southern Haryana and Maharashtra's Vidarbha over multiple days until 24 April....