The fiber properties and processing behavior of gin-dried cottons were determined on Deltapine 15 cotton from the Mississippi Delta area. Several comparisons were made of hand-harvested and machine-havested cottons. Growth conditions had an important influence on the short-fiber content and spinning properties. High short-fiber contents in ginned lint persisted after processing into card sliver. Examination of fibers from length arrays indicated a preferential breakage of fine and immature fibers during ginning and cleaning. At spindle speeds that cause a large number of ends to break, the number of breaks during each hour was related to the running hour of the doff. The spread in number of breaks per doff decreased as number of end breaks decreased. End breakage in spinning increased with gin drying for hand-harvested cotton, but had a minimum at an intermediate drying level for machine-harvested cotton. Yarn grade and strength for both types of harvesting decreased with gin drying. Overdried lint from center segments of bales when processed without preconditioning had higher end breakages than lint from the outer segments.

The influence of seed size on emergence of seedlings and plant development was studied in a number of trials with special reference to seeding depth. The results of the study lead to the following conclusions: The number of emerging seedlings and the number of developing shoots per 100 sown germinative seeds were smaller with small seeds than with large seeds. The influence of seeding depth on the percentage of emerging seedlings was more marked with small seeds than with large seeds. Differences were found between different crops. The strongest dependence of the observed quantities on seed size was displayed by winter rye at a great seeding depth. The differences between the studied crops could not be explained on the basis of differences in 1000-seed weights.

SynopsisNitrogen fertilization caused increases in the grain yield, number of culms per plot, plant height, and straw weight of all varieties. None of the varieties showed an effect on the calculated number of kernels per head. The effects of fertilization on 100-kernel weight, heading date, test weight, and straw-grain ratio were variable.

SynopsisGrain yields were curvilinearly related to the number of irrigations, depletion of soil moisture, and increments of applied N. Evapotranspiration was related to number of irrigations and to available soil moisture. Plant growth response to applied N increased evapotranspiration slightly. Irrigation and applied N both increased the efficiency of water use. Maximum efficiency occurred at a yield level below maximum production.