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Abstract
Leaves from succinic acid-2,2-dimethylhydrazide (daminozide)-treated seedlings of ‘McIntosh’ apple (Malus domestica Borkh) accumulated significantly more 45Ca than those from 1-napthaleneacetic acid (NAA)-treated seedlings. Stem sections from daminozide-treated seedlings accumulated significantly more 45Ca than stems from control seedlings. Total 45Ca content in daminozide-treated seedlings was significantly greater than in either controls or NAA-treated seedlings. The expected reduction in total shoot length by treatment with daminozide, NAA + daminozide and NAA was noted. The increases in 45Ca content in all treatments appear to be due in part to the concentration effect of reduced shoot growth and in part to an effect of daminozide on rate of uptake.
Abstract
Strip tillage was evaluated over a 2-year period as a cropping system for sites unsuitable for conventional tillage. Yields in clean cultivation and in 0.5- and 1.1-m strips tilled in established grass or grass/clover sod were compared in 1982 for sweet pepper (Capsicum annuum L.) and winter squash (Cucurbita maxima L.). Both interspecific and intraspecific competition were determined in 1983 for pepper. Squash yield was improved by a grass/legume sod, but pepper yield was unaffected. Both crops suffered severe competition in 1982 when grown in 0.5-m-wide strips, but yields per hectare in strips 1.1m wide equaled that in clean cultivation. In 1983, however, number of marketable fruit per hectare of marketable yield of pepper in 1.1-m strips was less than that in clean cultivated plots, although total number of harvested fruit did not differ. Both marketable and total pepper yields per hectare were significantly higher in clean cultivation in 1983 than in strips. Increasing the population density of pepper in the strip increased number of fruit harvested and total weight per hectare, and there was a significant benefit in using double rows. Competition in strips accompanying increasing population density seemed to be associated with increased water deficits.