In cotton–wheat cropping system of Pakistan, wheat (Triticum aestivum L.) is harvested in late April; however, the optimum sowing time of Bt cotton is mid-March. This indicates a time difference of 4–6 weeks between the harvest of wheat and cotton sowing. It is hypothesized that this overlapping period may be managed by transplanting cotton seedlings (30–45 days old) in late April, after the harvest of wheat due to better performance of already established seedlings. To this end, this study was conducted to evaluate the allometric traits and fiber quality of transplanted Bt cotton after harvesting wheat in the cotton–wheat cropping system. The Bt cotton–wheat cropping systems were flat sown wheat (FSW)–conventionally tilled cotton, FSW–zero tilled cotton, ridge sown wheat–ridge transplanted cotton using 30- and 45-days-old seedlings, and bed sown wheat (BSW)–bed transplanted cotton (BTC) also using 30- and 45-days-old seedlings. The study was conducted at Vehari and Multan in Punjab, Pakistan. Bt cotton in BSW–BTC with 45-days-old seedlings showed better performance for allometric (leaf area index; (LAI), net assimilation rate; (NAR), and crop growth rate; (CGR)), seed cotton yield, and fiber traits (fiber uniformity, fiber length, fiber strength, and fiber fineness) in comparison to other treatments. Most of the fiber quality traits were positively correlated with allometric traits and biological yield (dry matter yield at maturity) at both locations, except correlations of CGR and LAI with fiber fineness and fiber length and NAR with fiber length. As plant growth and fiber quality of transplanted cotton was significantly higher than conventionally grown cotton, our data indicate transplanting is an interesting management practice for improving productivity in wheat–cotton cropping systems.

中文翻译：

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移栽改善Bt棉在棉麦种植系统中的异速生长和纤维品质

在巴基斯坦的棉小麦种植系统中，小麦（小麦L.) 在四月下旬收获；但 Bt 棉的最佳播种时间是 3 月中旬。这表明小麦收获和棉花播种之间有 4-6 周的时间差。据推测，这一重叠期可以通过在 4 月下旬在小麦收获后移植棉苗（30-45 天）来管理，因为已经建立的幼苗性能更好。为此，本研究旨在评估棉麦种植系统中小麦收割后移植的 Bt 棉花的异速生长特性和纤维质量。Bt棉花-小麦种植系统是平播小麦（FSW）-常规耕作棉花，FSW-零耕棉花，垄播小麦-垄作棉花使用30天和45天龄幼苗，和床播小麦 (BSW)-床移栽棉花 (BTC) 也使用 30 天和 45 天龄的幼苗。该研究是在巴基斯坦旁遮普邦的 Vehari 和 Multan 进行的。具有 45 天龄幼苗的 BSW-BTC 中的 Bt 棉花在异速生长（叶面积指数；（LAI），净同化率；（NAR）和作物生长率；（CGR））、籽棉产量和与其他处理方法相比，纤维特性（纤维均匀度、纤维长度、纤维强度和纤维细度）。除了 CGR 和 LAI 与纤维细度和纤维长度以及 NAR 与纤维长度的相关性外，大多数纤维品质性状与异速生长性状和生物产量（成熟时的干物质产量）呈正相关。由于移植棉花的植物生长和纤维质量明显高于常规种植的棉花，