Mineral Nutrition Status of Valencia Orange


quate". However, in group "B" where the supply of moisture
may have been a limiting factor, lower fruit production was
seen in groves sprayed with oil.

 TABLE 22.-THE INFLUENCE OF OIL AND PARATHION ON THE FRUIT
 PRODUCTION OF VALENCIA ORANGE (1955-1956).

 Material Group "A" Group "B"
 Groves 1 Average Yield I Groves Average Yield
 Boxes/ Boxes/ xes Boxes/ Boxes/A.
 No. Tree A. No. Tree
 Oil ..... 44 6.72 449 36 4.60 290
 Parathion-oil 15 6.75 448 26 5.02 331
 Parathion ..... 11 6.75 442 12 5.25 347

 Statistical significance n.s. n.s.
 "A"-Groves received 42 to 50 inches of water either through precipitation or supple-
 mental irrigation.
 "B"-Groves received 32 to 41 inches of water either through precipitation or supple-
 mental irrigation.

 One of the precautions in using oil is "do not apply oil spray
 when trees are wilting or near wilting" (1). It is doubtful if trees
 in any of the groves were actually in that stage at the time of
 oil application, as most growers are quite conscious of the pre-
 caution. Possibly the wilting of the trees in days following the
 oil spray, together with the duration of the residual effects of oil,
 brought about the observed effect on yield.

 INFLUENCE OF IRRIGATION
 The supply of adequate moisture was probably one of the
most important factors limiting fruit production during the
1955-56 season. Supplemental irrigation was applied to about
half the groves under study. The majority of the irrigated
groves yielded well, but some yielded better than others. It
is obvious that, among other factors, local weather conditions
and time and rate of irrigation may have influenced crop yield.
Because of the wide variations observed in annual rainfall, it
seemed desirable to group the groves according to geographi-
cal locations and compare the effects of supplemental irriga-
tion within each area. It was apparent from the data in Table
23 that the effects of supplemental irrigation were closely re-
lated to the rainfall. In areas where the annual rainfall was
low, as in Highlands County and parts of Polk, benefit derived
from supplemental irrigation was much more pronounced. Light
irrigation, although it produced more fruit than non-irrigation,