The primary objective of sugarcane (Saccharum spp.) variety testing programs is to identify cultivars that have high cane yields and good ratooning ability (RA). The purpose of this study was to evaluate the usefulness of six RA indices to estimate RA among sugarcane varieties and to identify an index well suited to predict RA in long-term ratoon crop cycles. The six indices were as follows: ratoon crops yield means, second ratoon to plant cane yield ratio, final ratoon crop to plant cane yield ratio, mean of ratoon crops to plant cane yield ratio (RP), linear regression, and quadratic regression. Data from four variety trials consisting of eight post-release varieties plus a control, harvested early, mid, and late in the cropping season for over six crop cycles, were used to estimate the RA indices. To identify indices that can predict RA in long-term ratoon crop cycles, simple linear regression analyses were used to compare the RA indices derived from 6-year crop cycles and similar indices derived from data from 111 commercial fields harvested over 11 successive crops. Coefficient of determination (R²) values plotted against their respective ratoon crop numbers were used to determine the minimum number of ratoon crops required to accurately predict RA indices for the 11-year crop cycle. The six indices varied in their rankings of the RA of varieties, emphasizing the importance of identifying the most appropriate indices for different ratooning practices. Based on its highest R² value of 0.92, the RP index was identified as the most accurate index to predict RA in long-term ratoon crop cycles requiring a minimum of five successive crops.

中文翻译：

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甘蔗品种再生能力指标

甘蔗（ Saccharum spp.）品种测试计划的主要目标是鉴定具有高甘蔗产量和良好再生能力（RA）的品种。本研究的目的是评估六个 RA 指数在估计甘蔗品种 RA 方面的有用性，并确定一个非常适合预测长期再生作物周期中 RA 的指数。六个指标分别为：宿根作物单产平均值、次生宿根与植物甘蔗产率、最终宿根作物与植物甘蔗产率、宿根作物与植物甘蔗产率均值（RP）、线性回归和二次回归。来自四项品种试验的数据用于估计 RA 指数，其中四项试验包括八个上市后品种和一个对照品种，在作物季节的早、中、晚收获，历经六个作物周期。为了确定可以预测长期宿根作物周期中 RA 的指数，使用简单线性回归分析来比较从 6 年作物周期得出的 RA 指数和从 11 个连续作物收获的 111 个商业田的数据中得出的类似指数。根据各自的宿根作物数量绘制的决定系数 ( R ² ) 值用于确定准确预测 11 年作物周期的 RA 指数所需的最小宿根作物数量。这六个指数对品种 RA 的排名各不相同，强调了为不同再生实践确定最合适指数的重要性。基于其最高R ²值 0.92，RP 指数被确定为预测至少需要五次连续作物的长期宿根作物周期中 RA 的最准确指数。