COTTON I1ST WEEVIL-CONTROL EXPERIMENTS 



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at weekly intervals thereafter. While this method did not give the 

 actual date of appearance of the first floral bud on each plant, the 

 beginning of the fruiting stage of the plants may be determined with 

 sufficient accuracy from the first week when the presence of squares 

 was recorded. Table 2 shows the 

 date when squares were first re- 

 corded in each planting, together 

 with the average height, number 

 of nodes, 1 and the average number 

 of squares formed. 



A more vigorous growth of seed- 

 lings in the later plantings is shown 

 by these records. The rate of 

 growth increases with each later 

 planting, the rate of formation of 

 nodes on the axis being more rapid, 

 while the length of the internodes 

 also increases. The faster devel- 

 opment of nodes reduces the in- 

 terval between planting and the 

 appearance of the first squares. 



The more rapid formation of 

 nodes on plants of the later plant- 

 ings probably was due to higher 

 temperatures during the early 

 stages of growth. Seedlings in the 

 later plantings did not encounter 

 cooler, weather, which may have 

 checked the growth in earlier 

 plantings. 



In comparing the rate of nodal 

 growth of seedlings, theperiod from 

 germination of the seed to appear- 

 ance of squares is used. Table 3 

 gives the date when germination 

 was first noted in each planting, the 

 number of days from germination 

 to the first record of square forma- 

 tion, the average number of axis 

 nodes formed during that period, and the average maximum and 

 minimum temperatures for the same period. 



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Fig. 2.- 



Diagram of successive plantings of cotton 

 at San Antonio, Tex. 



Table 2. — Average development of 10 cotton plants at the beginning of the fruiting 

 stage as grown in successive plantings at San Anionio on four different dates 



Date planted, 1023 



Squares 



first 

 recorded 



Number 

 of days 



from 

 planting 



Height 



of 

 plants 

 (centi- 

 meters) 



Number 

 of nodes 



main 

 stalk 



Average 

 number 



of 

 squares 



Apr. If/. 

 Apr. 28. 

 May :,. . 

 May 12. 



June 1 

 June 8 



...dO„„. 



June 15 



21.5 

 23.4 

 22.6 

 24.4 



6.5 

 7.1 

 6.2 

 5.9 



2.2 

 2.8 

 1.9 

 1.7 



1 All records of the number of nodes on the main stalk are exclusive of the cotyledon node. 



