Nitrogen Nutrition of Distichlis (Saltgrass) under
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                                   Normal and Salinity Stress Conditions Using                                                           N
                                                                        MohammadPessarakli
                                                                            University of Arizona
               Objectives:
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                          1. To determine nitrogen uptake of saltgrass under salt stress conditions using               N.
           Start Date: 2008                                                                                                            increase in nine out of the
           Project Duration: two years                                                                                                 twelvevarieties (A49,A50,
           Total Funding: $6,000                                                                                                       A60, 72, A86, A107, A126,
                                                                                                                                       239 and 240) in the plants
                    Saltgrass (Distichlis spicata) is a                                                                                grown under saline condi-
                                                                                                                                       tions compared to the con-
           warm-season potential turfgrass species                                                                                     trol,  with variety A136
           that has the ability to grow under highly                                                                                   being equal under the both
           saline, poor soil conditions, and with limit-                                                                               salt conditions.
           ed available water and nutrient (i.e. nitro-                                                                                   Root       DM        weight
           gen) sources. This characteristic could                                                                                     showed an increase in eight
           prove to be beneficial in certain turfgrass                                                                                 of the ten varieties (A49,
           areas requiring low maintenance in arid                                                                                     A50, 72,A86,A107,A126,
           regions with saline soils and limited water                                                                                 A136 and 240) grown
           or low fertility/limited nutrient contents                                                                                  under saline conditions.
           and poor soil conditions. Growth of this                                                                                    Thepercent root DM (aver-
           species could be important to aid in con-             Grasses were grown under saline (NaCl) conditions at EC of 20 dSm-1   age    dry   weight/average
           servation of water and nutrients and use of           using a hydroponic technique using Hoagland solution.                 fresh     weight)      showed
           salt-affected soils. Test of the species' abil-      harvest were analyzed. At the termination            increased DM production in seven of the
           ity to grow under highly saline conditions           of the experiment, plant roots were also             ten varieties (A37, A50, A60, 72, A86,
           and limited nutrients, as well as low avail-         harvested, oven-dried at 60º C and DM                A126 and 240) grown under saline
           able water sources, are needed before it             weights were measured and recorded.                  conditions.
           can be applied to a turfgrass system.                           The results of the average shoot                     The partial results of the 15N
                      Twelve saltgrass genotypes (A37,          length per week showed a decrease in all             analysis show a substantial increase in
           A49, A50, A60, 72, A86, A107, A126,                  varieties of plants grown under saline con-          nitrogen concentration of the plant tissues.
           A136, A138, 239 and 240) collected from              dition compared to the control. The root             This indicates that saltgrass is a true halo-
           several southwestern states of the United            length for the duration of the experiment            phyte and accumulates the extra N in its
           States were studied in a greenhouse to               showed increased root growth of eight of             tissues which can be gradually available to
           evaluate their growth in terms of shoot and          the twelve varieties grown under saline              the growing parts of the grass.
           root lengths and dry mater (DM) weights              condition when compared to the control.                           SummaryPoints
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           (shoot clipping weight) and nitrogen ( N)            These eight varieties include A60, A86,
           uptake under salt stress condition. The              A107,A126,A136,A138, 239 and 240.                          The results of this experiment con-
           grasses were grown under saline (NaCl)                          All varieties, except A86, pro-           firmed that saltgrass has a high salt toler-
           conditions at EC of 20 dSm-1 using a                 duced a higher weekly average fresh                  ance and is a true halophyte.
           hydroponic technique using Hoagland                  weight for control plants than those grown                Root length, root fresh wt., root DM
           solution. A randomized complete block                under saline conditions. The fresh weight            wt., percent shoot, and root DM wts. in
           (RCB) design trial was used with four                of the roots showed an increase in six of            plants grown under saline condition
           replications of each genotype and each               ten of the varieties (A49, A86, A107,                increased.
           treatment. Nitrogen (15N) was used to                A126,A136and240)for the plants grown                      The amount of DM produced is the
           determine the exact amount of N taken up             under saline conditions. Two of the vari-            most significant result as it is a direct rep-
           by the plants.                                       eties, A138 and 239, did not produce                 resentation of saltgrass' ability to grow
                      Eachweek,theplant shoots (clip-           recordable root fresh weight.                        under highly saline conditions.
           pings) were harvested for the evaluation of                     The grass DM weight showed an                 Basedontheresultsofthisexperiment,
           the dry matter (DM) production. At each              increase in ten of the twelve varieties              each of the tested varieties had a high
           harvest, both the shoot and root lengths             (A37, A50, A60, 72, A107, A126, A136,                degree of salt tolerance.
           were measured and recorded. The harvest-             A138, 239, 240) and in the control plants                                                 15
           ed plant materials were oven-dried at 60ºC           in comparison to those grown under saline                 Based on the results of the        Nanaly-
           and DM weights were measured and                     conditions. However, the percent DM                  sis, all the clones accumulated significant
           recorded. Six harvests were included in the          weight of the shoots (average dry                    amounts of nitrogen in their tissues under
                               15                                                                                    salinity stress condition.
           experiment. The       Nsamples for only one          weight/average fresh weight) showed an
           2008 USGATurfgrass and Environmental Research Summary                        70