ESTIMATES OF MARKETABLE YIELD IN ASPARAGUS USING FERN VIGOR INDEX ANDA MINIMUM NUMBER OF DAILY HARVEST RECORDS

Fern vigor indices and estimates of percent marketable yield (PMY) wer e used to determine alternative measures of asparagus (Asparagus offic inalis L.) marketable yield. Total yield was highly correlated (0.75 l ess-than-or-equal-to r less-than-or-equal-to 0.91), and marketable yie ld was not correlated with fern vigor indices. The products of fern vi gor indices and seasonal PMYs were highly predictive of marketable yie ld (r greater-than-or-equal-to 0.95). When the products of each daily PMY estimate and fern vigor index for the same season were determined, then averaged over years, <30% of correlations with marketable yield were less-than-or-equal-to 0.90, and r values varied considerably duri ng the season. The products, averaged for 2 years, of fern vigor index and mean PMY estimated from combinations of three harvest dates durin g the season, except from the first harvest week, were associated with marketable yield. For the 40 3-day average estimates of PMY examined, 95 % of Pearson correlation coefficients were greater-than-or-equal-t o 0.90 and all were greater-than-or-equal-to 0.88. Thus, fern vigor in dex and PMY estimates from three harvest dates may be used to predict temperate zone marketable yield, decreasing labor requirements for yie ld trials, and facilitating evaluation of many experimental hybrids.