Version: 2018.4
public ParticleSystem.MinMaxCurve rateOverTime ;

Description

The rate at which new particles are spawned, over time.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { private ParticleSystem ps; public float hSliderValue = 5.0f;

void Start() { ps = GetComponent<ParticleSystem>(); }

void Update() { var emission = ps.emission; emission.rateOverTime = hSliderValue; }

void OnGUI() { hSliderValue = GUI.HorizontalSlider(new Rect(25, 45, 100, 30), hSliderValue, 5.0f, 200.0f); } }