Pakistan is placed among the most vulnerable countries with relation to climate change and its impacts on agricultural productivity. Cotton is staged as the cash crop of the country and the main source of raw material for textile, oil, and feed industry. Varying environmental attributes have significant effects on the duration of vegetative and reproductive stages of cotton crop. To evaluate the potential impacts of varied temperatures regimes in different sowing times, field experiments were carried out throughout the cotton growing areas of Pakistan from Faisalabad in Central Punjab to RYK in Southern Punjab and Sakrand in Sindh to Dera Ismail Khan in Khyber Pakhtunkhwa (KPK) Province. Crop was sown on six different sowing dates starting from 1st March towards 15th May with 2-week intervals for two crop seasons (2016 and 2017). The timing of phenological events like emergence, squaring, flowering, and boll opening was recorded on calendar days and cumulative heat units (GDDs) were calculated for flowering and boll opening stages. Heat use efficiency for these sowing times was estimated. Data regarding yield-related parameters like opened bolls per plant, average boll weight, and seed cotton yield were also recorded during the study. Results revealed that duration of the growth stages was significantly affected by variation in mean thermal kinetics in varied sowing times in all four different environments. Seed cotton yield and heat use efficiency were also varied among the locations and sowing dates. The maximum seed cotton yield was recorded in Sakrand location at 15th April sowing date. The dependence of the phenological advancement on temperature and negative impacts of higher thermal stress on cotton productivity were also confirmed throughout the cotton growing zone of Pakistan.

在气候变化及其对农业生产力的影响方面，巴基斯坦被列为最脆弱的国家之一。棉花是该国的经济作物，也是纺织、石油和饲料工业的主要原材料来源。不同的环境属性对棉花作物的营养和生殖阶段的持续时间有显着影响。为了评估不同播种时间的不同温度条件的潜在影响，在巴基斯坦的棉花种植区进行了田间试验，从旁遮普邦中部的费萨拉巴德到旁遮普邦南部的 RYK 和信德省的 Sakrand 到开伯尔普赫图赫瓦省的德拉伊斯梅尔汗 (KPK)省。从 3 月 1 日到 5 月 15 日，作物在六个不同的播种日期播种，两个作物季节（2016 年和 2017 年）间隔 2 周。在日历日记录诸如出苗、开平方、开花和吐铃等物候事件的时间，并计算开花和吐铃阶段的累积热量单位 (GDD)。估计了这些播种时间的热利用效率。研究期间还记录了有关产量相关参数的数据，例如每株开铃数、平均铃重和籽棉产量。结果表明，生长阶段的持续时间受到所有四种不同环境中不同播种时间的平均热动力学变化的显着影响。种子棉花产量和热量利用效率也因地点和播种日期而异。Sakrand 地区在 4 月 15 日播种日期记录了最大的籽棉产量。