NCP in cultivated tomatoes from the Chile-Peru frontier.<p>

Rick, C. M.  <p>

During a visit to this border region early in 1957 I had opportunity to
collect material to provide a good estimate of the amount of natural
cross-pollination in cultivated tomatoes.  The experiment was not planned, but
was made to order by the presence of about 5% plants with potato leaf (c) in
all fields that I visited in this region.  This low, but consistent appearance
in local varieties is an intriguing situation, per se, suggesting that c might
have some selective advantage.  I doubt that the growers, who save their own
seed, intentionally select in favor of c, because the five growers with whom I
conversed were not even aware of the difference in leaf shape between c and +
until I called it to their attention.  Plants in all observed fields had been
fruiting for several months and were staked and intimately intermingled,
providing a good opportunity for cross-pollination.<p>
     
Collections were made in three fields, but growth was so poor and the number
of plants so small in the planting in the Lluta valley in northern most Chile,
that insufficient seeds were collected there to provide a satisfactory
estimate.  The other two collections were made in the Tacna Valley in southern
Peru, -- one in the outskirts of Tacna and the other at Calanal 13 km.  east
of Tacna.  Growth in both fields was good.  The fields were veritably alive
with various small species of Halictidae, none of which was I fortunate enough
to capture.  Seeds were extracted and kept separate for each fruit from the
two plantings.  The identifications of the seedlings grown from this seed are
summarized as follows:<p>
<pre>
          
                     Seedlings
        No. of  ___________________             Adjusted
Source  fruits   +      a     Total       %+     % NCP
__________________________________________________________
Calana    15    420   1692    2112      19.9     25.7
Tacna     10    202   1555    1757      11.5     14.8
Total     25    622   3247    3869      16.1     20.8
</pre>
Knowing that approximately 5% of the plants in both fields were c/c, the gene
frequency for c can be estimated at 22.4%.  Since the products of c x c
fertilizations would go undetected, the proportion of + seedlings must be
adjusted by the factor 1/0.776.  The estimates of NCP thus obtained are given
in the last column.  These values correspond with my previous estimates of NCP
of tomatoes in coastal Peru and provide an interesting comparison with values
reported for cultivated tomatoes of Mexico by Alvarez and Richardson, who used
the same technique reported here.<p>
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