One of the factors limiting jojoba (Simmondsia chinensis (Link) Schneid.) production in the USA has been frost damage to flower buds. Research indicates that drought can be used to increase the frost tolerance of jojoba. In certain other plants, frost-hardiness is related to an increase in soluble carbohydrates including pinitol. D-Pinitol is also present in jojoba and is a major soluble sugar constituent of its leaves and buds in the fall and winter. In this study we evaluated the influence of irrigation water management, season and clone on pinitol content of jojoba over a 2 year period. The plants studied were from two clones in two irrigation regimes: a wet treatment (WT) that received water biweekly throughout the growing season, and a dry treatment (DT) that received no irrigation water after June to provide fall and winter water stress. Leaf water potential and relative water content were lower in the fall and winter in the DT than in the WT. Water stress did not appear to stimulate pinitol accumulation in jojoba leaves or flower buds. Pinitol content of leaves was highest in the spring and lowest in the summer. There were no consistent differences between clones in pinitol content of tissue.

Flower bud injury resulting from freezing temperatures has been a major problem in jojoba [Simmondsia chinensis (Link) C. Schneid.] production. A 3-year field study, which began with 4-year-old plants, evaluated the effect of three irrigation treatments on growth, flower bud survival, seed yield, seed weight, and seed wax concentration of six clones. After 3 years, irrigation cut-off dates of late May (dry treatment) and early September (medium treatment) resulted in reduced plant height and width compared to irrigating through November (wet treatment). Flower bud survival and seed yields were very low in the first year for all treatments. In the second and third years, bud survival for most clones, even at -8C, was greatly improved by withholding water in the fall. In December of the second and third years, plants in the medium and dry plots had lower leaf water potential than those in the wet plot. In the second year, plants in the medium and dry plots had seed yields that were 3.5 times higher and wax yields that were were 2.3 times higher than plants in the wet plot. In the third year, the medium treatment had the highest seed and wax yields. Average seed weight and seed wax concentration were generally highest for plants in the wet plot where seed yields were low. Withholding irrigation from jojoba in the fall appears to improve flower bud survival and seed and wax yields following cold winters.

Plant Growth Regulators (PGR's) are used in cotton production to reduce excessive vegetative ,growth. This study was conducted to determine the effect of mepiquat chloride (PIX) on growth, and yield of Pima S7 and Deltapine 90 cotton. Single and multiple applications of PIX were conducted over the growing season. Plant mapping measurements were performed 13 times. Seed cotton yield estimates were obtained with a mechanical picker. Analysis of the mapping data showed that vigor index for control and PIX treated Pima and Deltapine plants was linear for the first 9 weeks, then leveled off as flowering and boll set occurred. PIX treated Pima plants were approximately 5cm shorter than the control after the 9th week. Heights of PIX treated Deltapine were similar to the controls. The number of nodes above white bloom in the FIX treated plants was not modified. PIX treatment of Pima cotton reduced the seed cotton yield compared to controls but yield of PIX treated Deltapine was similar to the controls.

Water Stress caused reduction of seed yield in cowpea plants by decreasing total biomass and photosynthesis. The source leaf, pod and seed water potential of stressed cowpea were lower than water potential in non -stressed plants. No differences in water potential and turgor were observed between pod walls and seed of cowpea plants. Partitioning of the total above ground dry matter was similar for both stressed and nonstressed cowpea plants. Photosynthetic rates of single leaves from cowpea were greater for nonstressed than stressed plants. The duration of seed growth of cowpea was not different between stressed and nonstressed plants; however, rate of seed growth at the end of seed filling period was greater in nonstressed plants. Seed growth rate of both stressed and nonstressed cowpea plants declined at about the same time photosynthesis of the source leaf declined. Leaf area index was greatest in nonstressed cowpea.

Osmotic adjustment is one of the adaptive responses of plant species to salinity, In tepary bean seedlings, salinity led to osmotic adjustment in different parts of the seedlings. The osmotic potential of the leaves increased to 340rnM(1MPa)in seedlings treated with 0.75 MPa NaCl. Water and osmotic potential of leaves and proximal parr of the roots were more negative than the controls whereas the turgor potential remained about the same. The osmotic adjustment of the tepary bean may result from the synthesis and accumulation of free sugars and amino acids or the accumulation of inorganic ions within the tissue. A quantitative analysis of the sugars and amino acids from salt stress treated tepary bean seedlings showed that they would contribute only -0.15 MPa to the osmotic adjustment whereas inorganic ions would contribute -0.45 MPa. The sum of these osmotic potentials is -0.6 MPa which is -0.4 MPa short of the observed osmotic values. These results suggest that additional substances also contribute to the osmotic adjustment of tepary beans. INTRODUCTION Salt accumulation in agricultural soils is an increasing problem for agricultural productivity in arid and semiarid regions of the world. Many primary agricultural areas in western U.S. such as California and Arizona, in spite of sophisticated agricultural systems, are now facing salt problems due to irrigation with water containing high levels of salts. Sodium chloride salinity adversely affects the growth and yield of many crop plant species; however, some species have adapted to salinity. Beans are a classic example of a salt sensitive crop. Successful growth and reproduction of crop plants grown under saline conditions requires changes in their metabolism to cope with the salinity stress. Tepary beans have been reported not to tolerate dry climate and saline conditions (Goertz, 1988) but the mechanism of tolerance is still unknown and it is the aim of this research to elucidate the physiological basis of the tolerance. Tepary bean is an important dietary constituent of the Indian cultures such as O'odham, Pima, and Seri and has been cultivated by these tribes for centuries. MATERIALS AND METHODS White tepary bean, $haseolus actifoliug andnavy bean (Phaseolus vulgaris) seeds were germinated in vermiculite for 5 days and the resulting seedlings transferred to solutions of aerated modified Hoagland's solution. Seedlings were grown at 25C under photoperiod of 13 hr with light intensity of 400 u Em S at canopy level. Salt treatment began 24 hr after the transplanting and NaCIwas added to the Hoaglands medium in increments of 0.25 MPa per day until the desired level was reached. Salt solution of 0, -0.25, -0.50, and -0.75 MPa were used in this study. Plant height, shoot fresh and dry weights and leaf area were measured. All measurements were conducted every three days. Free amino acids were extracted and estimated by the methods of Bieleski and Turner (1966). The free sugars were extracted in the same way as the amino acids but quantitative of sugars was conducted by the methods of Dubois, et al, 1956 and HPLC procedures (Miller, 1989). The osmotic and water potentials were determined with Merrill thermocouple psychrometer. The stored data from the psychrometer

AbstractThe cooling towers at the Palo Verde Nuclear Generating Station (PVNGS), located 80 km west of Phoenix, AZ, will release an estimated 2.1 Mg/d of particulates (primarily salts) into the atmosphere when the station is in full operation. The saline drift will disperse and settle onto agricultural fields surrounding the station. Field studies were conducted in 1953 to investigate the influence of foliar‐applied saline aerosol on crop growth, foliar injury, and tissue elemental concentration on cotton (Gossypium hirsutum L.), alfalfa (Medicago sativa L.), and cantaloupe (Cucumis melo L.) in an arid environment. The treatment aerosol solutions simulated treated wastewater effluent and included all essential plant nutrients and other elements, including trace concentrations of heavy metals. The treatments included unsprayed plots, and plots sprayed with salt solutions at 0 (distilled water), 8, 83, and 415 kg/(ha yr). The alfalfa received an additional 829 kg/(ha yr) treatment. The species were evaluated in separate experiments on Mohave clay loam and Sonoita sandy loam soils (Typic Haplargid) near Marana, AZ. Cotton treated with 415 kg/(ha yr) had significantly less chlorosis and tended to be slightly taller than the cotton in the unsprayed plots. The alfalfa treated at a rate of 829 kg/(ha yr) showed significantly more leaf margin necrosis than did the unsprayed alfalfa. In the cantaloupe, there were no visually apparent differences among salt treatments. Hand‐harvested cotton plots had a significant reduction in seed cotton yield at the 415 kg/(ha yr) treatment (P ≤0.05). A similar though nonsignificant, trend towards reduced yield with increased salt treatment was observed in machine‐harvested cotton plots. No significant yield differences were detected in the alfalfa or cantaloupe.

The impact of foliar salt deposition, similar to that which is predicted to occur in the vicinity of the Palo Verde Nuclear Generating Station, was investigated on cantaloupe and cotton. Simulated salt drift was applied throughout the growing season. There was an increase in the amount of lead found in the fruit harvested from the highest treatment level as compared to the untreated plants. No other observable saltinduced responses were observed in the cantaloupe. A trend toward reduced yields was observed in the cotton plots receiving the salt treatments.

Identification of the physiological processes involved in salt tolerance is required to develop appropriate selection criteria for breeding salt‐tolerant crops. For this purpose selected physiological characteristics were evaluated in five alfalfa (Medicago sativa L.) populations selected for NaCl tolerance during seed germination and the source population, 'Mesa‐Sirsa'. Seed of the populations (Syn‐1) was germinated in distilled water and solutions of NaCl, NaNO3, KC1, KNO3, and mannitol ranging from −1.0 to −1.6 MPa osmotic potential. The mean difference in percent germination between Mesa‐ Sirsa and ‘AZST1982’, the most salt‐tolerant population, was greater in the NaCl solutions than the other salt solutions (P < 0.01). Seed from AZST 1982 also had higher percent germination than Mesa‐Sirsa in mannitol solutions (90.6 and 2.8%, respectively, at −1.6 MPa osmotic potential). Mesa‐Sirsa had higher (P < 0.01) average seed respiration rate than AZST 1982 between 3 and 24 h of germination in NaCl solutions of −0.6 to −3.0 MPa osmotic potential. There was no significant difference between Mesa‐Sirsa and AZST 1982 for Na+ or Cl− accumulation after 48 h of germination in NaCl solutions of −0.6 to −1.8 MPa osmotic potential, or absorption of tritiated water after 6 and 12 h of germination in NaCl solutions of −1.3 and −2.0 MPa osmotic potential. Selection for NaCl tolerance in germinating alfalfa seed results in two separate types of tolerance: tolerance of an inhibitory effect specific to NaCl and tolerance of lowered water potential. Selection for NaCl tolerance of alfalfa during germination does not appear to influence ion accumulation or the rate of imbibitional water uptake.

Enzymatically isolated leaf cells from cotton (Gossypium hirsutumL. ‘Stoneville’) and soybean (Glycine max(L) Merr. ‘Kino’) were used to study the effect of SAN 6706 [4-chloro-5-(dimethylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone] on photosynthesis, protein, RNA, and lipid synthesis during the first 19 hr of herbicidal treatment. Cotton plants are tolerant to SAN 6706, whereas soybean plants are susceptible. SAN 6706 inhibited the incorporation of14C-bi-carbonate, uridine, and acetate into cotton leaf cells but stimulated incorporation of leucine. Incorporation of all of these precursors into soybean cells was inhibited. Cotton and soybean cells each took up equivalent amounts of labeled SAN 6706. The incorporation activity of the cotton and soybean cells appeared to regulate the entrance of the precursors into the cells by depleting the intracellular precursor pools. It is suggested that the inhibition of RNA and lipid synthesis in cotton and soybean cells is an indirect result of inhibited photosynthesis. Isolated cotton cells were not tolerant of the herbicide.

The mechanism of nuclear DNA replication in radicles of germinating cotton (Gossypium barbadense) was investigated. Pulse-labeling with [(3)H]thymidine indicates that replication intermediates are of small molecular weight (4-10S) and behave as if single-stranded. Prolonged labeling indicates that intermediates are of discrete size, suggesting a mechanism of discontinuous replication. Electron microscopy of nuclear DNA demonstrates a complex architecture which may include "eye forms" and "forks" similar to those reported in prokaryotes and animal systems. The possible universality of DNA replication mechanisms is discussed.

The synthesis of nuclear DNA and possible attachment sites of chromatin in the cells of cotton (Gossypium barbadense) radicles during germination was investigated. Biochemical analysis of nuclear membrane fragments or Sarkosyl-magnesium-membrane complexes indicates that the DNA, including newly replicated DNA, is attached to the nuclear membranes during periods of active synthesis. Electron micrographs of nuclear membrane fragments indicate a physical association between chromatin fibers and the membranes. The attachment site appears to be proteinaceous, since the chromatin is released by protein degradative enzymes as evidenced by biochemical techniques and electron microscopic observations. Short-term labeling results in incorporation into a membrane-associated product indistinguishable from the bulk of nuclear DNA. DNA polymerase activity is also associated with nuclear membrane preparations in which [3H]thymidine triphosphate is incorporated into an acid-insoluble. DNase-sensitive product.

The isolation of chloroplast and nuclear DNA from dark- and light-grown, control- and 3-amino-1,2,4-triazole-treated wheat seedlings, Triticum vulgare, is described. Contrary to a previous report, we found that chloroplast and nuclear DNA had similar buoyant densities (1.702 grams per cubic centimeter) and that they could not be resolved by buoyant density centrifugation in CsCl. Difference in renaturation behavior of the chloroplast and nuclear DNA was used as the criterion for distinguishing one from the other. Only chloroplast DNA readily renatured whereas nuclear DNA renatured only slightly. Light-grown, 3-amino-1,2,4-triazole-treated plants were found to lack detectable quantities of chloroplast DNA whereas treated, dark-grown plants contained plastid DNA. We suggest that 3-amino-1,2,4-triazole affects the accumulation of chloroplast DNA by inhibiting the formation of chloroplast membranes, enzymes, and pigments.

The application of sublethal doses of 3‐amino‐1,2,4‐triazole (AT) to germinating, light‐grown wheat grains causes chlorosis of the resulting leaves. An ultrastructural examination of the leaf tissue reveals that the plastids lack normal grana‐fret membrane systems and chloroplast ribosomes. A few disorganized membranes are always present in these chloroplasts. However, AT‐treated, dark‐grown seedlings contain proplastids with non‐crystalline prolamellar bodies and ribosomes. When these etiolated, treated plants are exposed to 600 ft‐c light for various periods of time, the proplastids fail to develop into normal, grana‐containing chloroplasts.

The most striking response of light-grown wheat seedlings to sublethal doses (0.1 m) of the herbicide Sirmate (3,4-dichlorobenzyl methylcarbamate) was the formation of achlorophyllous leaves. This herbicide did not inhibit seed germination and the leaves emerged normally, except that they had a bleached appearance. After 9 days, these plants died, presumably of starvation due to depletionofendosperm reserves. Postemergent application of Sirmate directly on plants caused contact injury or necrosis but did not induce chlorosis of mature green leaves. The mechanism of Sirmate's herbicidal action is still unknown, although Herrett and Berthold (5) suggested that Sirmate inhibited chlorophyll synthesis in light-grown seedlings, whereas in dark-grown plants the carotenoid pigments were not affected, quantitatively or qualitatively, by the Sirmate treatment. In the present investigation, we examined the effect of Sirmate on chloroplast ultrastructure and on the ribosomal population of darkand light-grown wheat seedlings.

The application of sublethal doses of 3-amino-1, 2,4-triazole (AT) to germinating wheat seedlings results in the formation of alibinistic leaves. These leaves grow and develop nearly as well as the control leaves for periods up to 1 week following germination (9). An tultrastrutctural examination of this tissue revealed that the chloroplasits were the only subcellular organelles altered morphologically by AT treatment. These altered chloroplasts lacked normal grana and fret membranes, but rather contained a few disorganized or concentric arranged membranes (2). In this study, we examined the effect of AT on the ribosomal composition of light-grown wheat leaves and found that the 70S chloroplastic ribosomes and 18S Fraction I protein of the chloroplast were absent. In addition, we confirmed earlier investigations (4, 5, 6, 8) which indicated that the chloroplasts contained only 70S ribosomes. Abotut 15 wheat grains (Triticum vulgare L. var. Seneca and Federation) were germinated in a petri dish containing 10 ml of 0.1 mm AT or distilled water. The plants were grown tunder 1000 ft-c of light (16 hr photoperiod, 21?) or in darkness. Following germination, distilled water was tused for the required watering and shoots were harvested on the seventh day and prepared for either ultrastructutral examination or sedimentation sttudies. For sedimentation studies, approximately 10 g of fresh leaf tissue were chilled and grouind in a mortar and pestle (2?) with an eqtual weight of stucrose-tris btuffer at pH 8.4 (7). The homogenate was strained throuigh 2 layers of cheesecloth, centrifuged for 30 mintutes at 23,000 X g (max, 1?) in a Servall SS-34 head and the suipernatant material was then centrifuged for 1.5 houirs at 226,000 X g in a Spinco 50 Ti head. The pellet was resuispended in a buiffer (pH 7.5) composed of 5 mM tris (Sigma) 7 mm magnesitum acetate and 5 mm mercaptoethanol, and clarified by centrifuging for 10 minuites at 8000 X g in an SS-34 head. The supernatant solution was removed and tused as the ribosomal suspension for the ultracentriftugal analysis on a Spinco MIodel E ultracentrifuge using a standard 12 mm, 40 sector cell in an AnD rotor. For electron microscopic stuidies, fresh tissue was fixed in 6 % glutaraldehyde (9 hr, 40) and embedded in Maraglas. Sections were cut with glass knives and double post-stained with aqueous uranyl acetate and lead citrate (3). Figure 1 shows a part of a chloroplast from an untreated, light-grown plant. The stroma (S) of this chloroplast contains many 170A particles (PR) which conform to the electron microscopical criteria for ribosomes since they were preserved by glutaraldehyde and osmium tetraoxide, strained 'with turanyl acetate and digested by ribonuclease (3). In contrast, a section of a plastid from an ATtreated plant (fig 2) showed that the stroma lacked ribosomal particles while the cytoplasm contained an abundance of ribosomes (CR). The ultracentrifugal pattern obtained with the ribosomal extracts from tissuie identical to those tused in the ultrastructural study is shown in figure 5. In this figuire, the direction of sedimentation was from left to right. Extracts from control, lighit-grown leaves (lower curve) showed 3 peaks with approximate sedimentation coefficients of 18S, 70S, and 80S and they represent Fractions I protein, chloroplastic and cytoplasmic ribosomes, respectively (4,5,8). In contrast, extracts of ATtreatedl, light-grown leaves (upper curve) yielded only an SOS peak, and the 18S and /OS peaks were completely absent in 5 separate experiments. In this sttudy, corrections were not made for viscosity effects duie to residual stucrose and protein concentration, therefore, the sedimentation valves are not exact. The comibined results of the tultrastructuiral and utltracentrifugal stuidies show that the treatment of light-grown, germinating seedlings with AT catused the complete loss of chloroplastic ribosomes and Fraction I protein but not cytoplasmic ribosomes. In contrast to the stuidies involving light-grown plants, AT treatment did not appear to alter the 1 Supported by grants from the USPHS (6F2HD-23, 340-OlAl) and the American Cancer Society.