The double pot technique was used to study the effects of uptake site of fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl—phenyl]-4(1H)-pyridinone} on early shoot and root development of soybean [Glycine max (L.) Merr. ‘Williams’] and cotton (Gossypium hirsutum L. ‘Acala SJ-1′). Soybean is susceptible and cotton is resistant to fluridone. Root uptake in soybean resulted in increased shoot length in the epicotyl and shoot apex, reduced shoot fresh weight, chlorosis of primary and trifoliolate leaves, as well as reduced root length, branching, and fresh weight. Shoot uptake resulted in reduced shoot length above the hypocotyl, reduced shoot weight, severe chlorosis of primary leaves, and inhibition of trifoliolate leaf formation. The reduction in the root length, branching, and weight was less by shoot uptake than by root uptake. In cotton, root uptake resulted in reduced shoot length in the epicotyl and shoot apex, slight reduction in shoot weight, no effect on chlorosis of cotyledon leaves, moderate to slight chlorosis of the true leaves, and no effect on root length, branching, or fresh weight. Shoot uptake resulted in reduced length of all shoot components and shoot weight, chlorosis of cotyledon leaves and the true leaves, and reduced root length, branching, and weight. Compared to soybean, cotton required much higher fluridone concentrations to show the above effects. It was generally concluded that in soybean, uptake by both the root and the shoot contributed significantly to the injury, whereas in cotton, shoot uptake was relatively more important.

This work was initiated to develop a method of sampling quackgrass populations. Shoot and bud distribution of 36 field populations was obtained. The results demonstrated that shoot count was inappropriate in assessing quackgrass bud populations and that bud sampling depth should be at least 20 cm if an accurate estimate is required. When shoot count is the only possibility, quadrat size should be as large as possible to minimize the error. Descriptive statistics of the field populations were used to generate a series of 24 simulated quackgrass bud populations. The field and simulated data were computer sampled with a program designed to compare the effects of varying sample size (number of quadrats) and sample shape (quadrat size and form). The intensity of sampling must be a function of resources and cost, since sampling precision increased linearly with sample size. Precision of sampling was generally higher when a large number of small quadrats were used compared to a small number of large quadrats. Sampling intensity per unit area must be increased when bud density increases to maintain a given degree of precision, but it can be decreased when plot size increases.

Napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] is a preemergence herbicide used for the control of most annual grasses and many annual broadleaf weeds. Its influence on the uptake and translocation of N, P, K, Ca, Mg, Cu, Fe, and Zn by four plant species was observed. Napropamide influenced, in some cases dramatically, the uptake and movement of the essential elements, but its influence was not consistent from one type of plant to another.

Graminaceous plants including staple cereals secrete certain phytosiderophores (PS) in calcareous soils with lower iron and zinc availability to enhance their uptake and translocation to the leaves and grains. A few Triticum aestivum cultivars and accessions of six Aegilops species were investigated for release of PS in vitro under iron- and zinc-sufficient and -deficient conditions, and for root and shoot iron and zinc concentrations. All the Aegilops species had three to four times higher release of PS than the wheat cultivars under both nutrient-sufficient and -deficient conditions. The maximum rate of increase of PS was observed on days 11 and 14 under iron- and zinc-deficient conditions, respectively, which levelled off rapidly among the wheat cultivars and continued to be high among Aegilops species till the end of the experiment. The absolute amount of iron and zinc expressed on dry weight basis after 18 d under iron- and zinc-deficient conditions showed nearly three times higher concentration in both roots and shoots of Aegilops species than that of the wheat cultivars. A significantly high correlation between concentrations of iron (r = 0.94) and zinc (r = 0.91) in roots and the PS released was found. The higher grain iron and zinc contents in the Aegilops species reported earlier may be attributed to their diverse and efficient mechanism(s) for PS-mediated micronutrient uptake and translocation system, which could be exploited for biofortification of wheat.