滨海盐碱地秋葵果实性状时序变化特征

Temporal variation of okra fruit traits in coastal saline-alkali soil

  • 摘要: 由治理盐碱地适应作物向耐盐碱植物适应盐碱地转变是盐碱地综合利用的新方向。在中重度盐碱地种植耐盐性强的高值作物秋葵, 不仅能降盐培肥, 还可提升盐碱地经济效益。本研究在河北省沧州市南大港中度盐碱地(全盐含量约4‰), 调查了秋葵果实发育过程中产量、色泽和营养组分及其之间关系的变化规律, 通过主成分分析和隶属函数法计算产量、色泽和营养的得分值, 为确定秋葵的最佳采摘时间提供指导。研究结果表明, 随着秋葵果实的生长发育, 其鲜重和干重持续增长, 在生长15 d时达到最大值7月最大干重为(12.31±0.27) g; 8月最大干重为(11.97±0.24) g; 9月最大干重为(7.45±0.19) g; 横径和纵径呈先快速增大后略微减小的趋势, 在花后11 d进入平台期(横径2.12~2.30 cm, 纵径14.00~17.75 cm)。叶绿素a含量呈略微上升趋势, 叶绿素b含量则逐渐下降, 总叶绿素含量保持稳定7月变异系数(CV)=3.56%; 8月CV=3.04%; 9月CV=10.07%。可溶性糖和类黄酮含量呈先升高后降低趋势, 在生长5~7 d时达到峰值最高值分别为(158.92±4.69) mg·g−1和(33.07±2.74) mg·g−1, 总膳食纤维含量则线性增长; 矿质元素钙呈现先降低后逐渐平缓的规律, 铁和锌含量变化不显著。产量形成、色泽变化与营养代谢存在明显的权衡关系, 但最优平衡点的出现时间在采摘月份之间存在差异。7—8月秋葵适宜的采摘期为果实生长5 d, 9月秋葵的适宜采摘期为生长7 d。研究结果可为盐碱地特色农产品开发提供理论支撑, 推动“以种适地”生态农业模式的实践应用。

     

    Abstract: The utilization of saline-alkali land is shifting from traditional remediation-based approaches to the adaptive cultivation of salt-tolerant crops. Okra Abelmoschus esculentus L. (Moench), a species with high salt tolerance, offers dual benefits when cultivated in moderately to severely saline-alkali soils, it enhances soil desalination and fertility while providing economic value. However, the temporal variation in okra fruit quality traits in saline-alkali environments — particularly the coordinated response patterns of yield components, color development, and nutritional metabolites across growth stages — remains poorly understood. This knowledge gap limits the development of targeted strategies for quality regulation in high-value agricultural production on marginal land. To address this, a field study was conducted in the saline-alkali region of Nandagang, Cangzhou (total salt content around 4‰), to analyze okra fruit traits at various growth stages. Key parameters included yield traits (transverse and longitudinal diameters, fresh and dry weights), chlorophyll content (chlorophyll a, chlorophyll b, total chlorophyll), and nutritional components flavonoids, soluble sugars, total dietary fiber, and mineral elements (Ca, Fe, Zn). The observed patterns were validated across different harvest months (July–September). Principal component analysis (PCA) and membership function methods were used to compute composite scores for the traits and identify optimal harvest times. The results showed that as okra fruits developed, both fresh and dry weights increased, peaking at 15 days post-anthesis (dry weight: 12.31 ± 0.27 g in July, 11.97 ± 0.24 g in August, and 7.45 ± 0.19 g in September). Fruit size grew rapidly initially and then stabilized at 11 days post-anthesis (transverse: 2.12–2.30 cm; longitudinal: 14.0–17.75 cm). Chlorophyll a content showed a slight upward trend, while chlorophyll b content decreased gradually. Total chlorophyll content remained stable with low variability (coefficient of variation: 3.56% in July, 3.04% in August, 10.07% in September). Soluble sugar and flavonoid contents peaked at 5–7 days post-anthesis (158.92 ± 4.69 mg·g−1 and 33.07 ± 2.74 mg·g−1, respectively), while total dietary fiber accumulated linearly. Mineral elements contents dynamics varied: Ca initially declined before stabilizing, while Fe and Zn showed no significant change. The developmental patterns of fruit size and weight, and chlorophyll b, total chlorophyll, and mineral elelements contents were consistent across the three harvest months. In contrast, trends in chlorophyll a, soluble sugar, flavonoid, and fiber contents exhibited month-specific variability. A trade-off was observed among yield, color, and nutritional components, with the optimal balance point differing by month. The results suggest that in saline-alkali environments, okra exhibits delayed morphological development but enhanced accumulation of osmotic substances. Recommended harvest times are 5 days post-anthesis for July and August and 7 days for September. These findings offer theoretical support for developing saline-alkali-adapted agricultural products, contribute to the implementation of the “planting suitable crops for specific lands” ecological model, and support the sustainable use of saline-alkali lands.

     

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