<br><div><section class="_135editor" data-role="paragraph" style="font-size: medium; max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; font-size: 15px; overflow-wrap: break-word !important; outline: none 0px !important;">　　（１）需水量：棉花的需水量或称田间耗水量，是指棉花从播种到收获，全生育期内本身所利用的水分及通过叶面蒸腾和地面蒸发所消耗水量的总和。据研究，亩产５０千克皮棉的棉田总耗水量为３００～４００米３ ，亩产１００千克皮棉则总耗水量为４５０米 左右。棉花不同生育时期需水量也３不同，总趋势与棉花生长发育的速度相一致。苗期棉株小，生长慢，温度低，耗水量较少；随棉株生长速度加大，耗水量也不断增加，到花铃期生长旺盛，温度高，耗水量最多；吐絮后，棉株生长衰退，温度较低，耗水量又减少。棉田的水分消耗，在苗期有８０％～９０％是从地面蒸发的，而棉株蒸腾耗水仅占１０％～２０％；蕾期地面蒸发和棉株蒸腾耗水各占５０％左右；花铃期地面蒸发和棉株蒸腾耗水分别占２５％～３０％和７０％～７５％；吐絮后地面蒸发和棉株蒸腾耗水又基本趋于相等。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; font-size: 15px; overflow-wrap: break-word !important; outline: none 0px !important;">　　（２）需水规律：棉花不同生育时期对土壤适宜含水量的要求不同。发芽出苗期，土壤水分以田间最大持水量的７０％左右为宜，过少种子易落干，影响发芽出苗；过多易造成烂种，影响全苗。苗期土壤水分以田间最大持水量的５５％～６０％为宜，过少影响棉苗早发；过多棉苗扎根浅，苗期病害重。蕾期土壤水分以田间最大持水量的６０％～７０％为宜，过少抑制发棵，延迟现蕾；过多会引起棉株徒长。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; font-size: 15px; overflow-wrap: break-word !important; outline: none 0px !important;">　　花铃期是棉花需水最多的时期，土壤水分以田间最大持水量的７０％～８０％为宜，过少会引起早衰，过多棉株易徒长，增加蕾铃脱落。吐絮以后，土壤水分以田间最大持水量的５５％～７０％为宜，利于秋桃发育，增加铃重，促进早熟和防止烂铃。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p></section><section class="_135editor" data-role="paragraph" id="autoparagraph" style="font-size: medium; max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; font-family: 微软雅黑, &quot;Microsoft YaHei&quot;, sans-serif; font-size: 17px; caret-color: rgb(255, 0, 0); overflow-wrap: break-word !important; outline: none 0px !important;"></p></section></div>