Photoassimilates partitioning in okra plants subjected to nitrogen doses

ABSTRACT Nitrogen (N) is the third nutrient more absorbed by okra. Therefore, an adequate supply of this element is essential for okra growth through the accumulation of dry matter in the leaves, stem, root and fruit. The objective was to evaluate the influence of N doses on growth, photoassimilates partition and yield of okra. The experiment was carried out in a Red-Yellow Argisol. A randomized complete block design with four replicates was used. The treatments consisted of N doses applied as topdressing (0, 60, 120, 240, 360 kg/ha). Samples of plants were held at 60, 75, 90, 105, 120, 135, 150 and 165 DAS for determination of the plant’s dry weight. The plant showed slow growth until 70 days, and after that time, intensified its growth until the end of the cycle. Total dry mass and absolute plant growth rate increased with increasing N availability, reaching the maximum marketable fruit yield of 10,665 kg/ha with 346 kg/ha N. The growth and partition of photoassimilates among the organs of the okra plant ‘Santa Cruz’ are altered with increasing nitrogen availability applied in topdressing.

摘要：氮（Nitrogen, N）是黄秋葵（okra）吸收量排名第三的营养元素。因此，该元素的充足供应是黄秋葵生长的必要条件，可促进其叶片、茎秆、根系及果实的干物质积累。本试验旨在探究施氮量对黄秋葵生长、光合同化物（photoassimilates）分配及产量的影响。试验在红黄色强风化粘磐土（Red-Yellow Argisol）上开展，采用随机完全区组设计，设置4次重复。处理组为追施（topdressing）的不同氮素用量，分别为0、60、120、240、360 kg/ha。分别于播种后天数（Days After Sowing, DAS）60、75、90、105、120、135、150和165 d采集植株样本，测定植株干重。黄秋葵的生长速率在播种后70 d前较为缓慢，此后生长速率显著加快，直至生育期结束。植株总干重与绝对生长速率随施氮量的增加而升高，当施氮量为346 kg/ha时，商品果产量达到峰值，为10665 kg/ha。追施氮肥量的增加会改变‘圣克鲁兹’（Santa Cruz）黄秋葵植株各器官的生长及光合同化物分配模式。