EFFECT OF DIFFERENT LEVELS OF NITROGEN FERTILIZER AND SOIL SUPPLEMENT AGRISPON 1 ON ROOT YIELD AND SUCROSE CONTENTS OF SUGAR BEET 2 (BETA VULGARIS)

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1 EFFECT OF DIFFERENT LEVELS OF NITROGEN FERTILIZER AND SOIL SUPPLEMENT AGRISPON 1 ON ROOT YIELD AND SUCROSE CONTENTS OF SUGAR BEET 2 (BETA VULGARIS) by I. Poostchi 3 ABSTRACT Monogerm sugar beet seed variety Sharpes Klein Monobeet was planted in April 1981 in Jiffy pots in the greenhouse and transplanted to the field. Three levels of nitrogen 0, 30, and 100 percent of the recommended rates (100 percent N = 142 kg/ha N and 3 levels of 0, 1 liter, and 2 liters per hectare were used. A factorial design of 3 X 3 giving 9 treatments and replicated 3 times was employed. Sugar beets were harvested on 22 October 1981 and necessary data recorded. Treatments receiving 0, 30 and 100 percent nitrogen using showed considerably higher yield of beet roots than corresponding treatments using nitrogen without. The same was true of root dry matter, and tons of sugar per hectare. Total yield of tops and total dry matter yield of tops was greater for different nitrogen levels using than corresponding nitrogen levels where was applied. -treated plots at lower levels of nitrogen application showed considerably higher drought tolerance and less reaction to moisture stress than did treatments having higher levels of nitrogen. INTRODUCTION There has not been a replicated trial carried out to show the relation of soil supplement with sugar beet. Preliminary data available indicated the stimulatory effect of in producing top growth. It is a general recommendation that nitrogen level in sugar beet roots, top and in the soil should be at a minimum a few weeks before harvest to allow for sugar to accumulate in the roots. Since has been used in other experiments with reduced levels of the recommended rates of nitrogen it was important to conduct an experiment to study the effects of reduced levels of nitrogen as measured in interaction with different levels of. MATERIALS AND METHODS Seeds of monogerm sugar beet variety Sharpes Klein Monobeet were sown in Jiffy pots (5 X 5 cm peat moss compressed pots) in the greenhouse on 22 April 1981 (second sowing 11 May) and allowed to germinate until 1-3 true leaves were developed. There were 1-3 beet seedlings per pot, which were thinned to only one strong seedling per pot at the 2-3 true leaf stage. Normal potting soil, John Innes potting compost soil consisting 7 parts loam, 3 parts peat and 2 parts sand to which was added N P K in proportionate amounts, was used to fill the Jiffy pots. Plots were sprayed for red spider on 22 June 1981 using Kelthanezo (an organochlorine acaricide). The plants were taken to open ground on 18 May 1981 when they had 3-4 true leaves. They were allowed to acclimatize for 10 days before they were transplanted to experimental site on 29 May. Plot size was 7.5 square meters (150 cm. by 5 meters) consisting of 3 rows of 5 meters long. Row spacing was 50 cm and plant spacing 20 cms. There were a total of 25 plants per row and 75 plants per plot. The extreme rows on each replicate had 4 rows instead of 3. The extra row was used to prevent hedge effect. 1 Experiment carried out under a grant provided by SnWn Associates of Dallas, Texas, USA 2 Work was carried out on land contracted by the parent company from the University of Reading by the University bears no responsibility for the results nor for the conclusions presented in this paper. 3 Research and Development Consultant for to SnWn Associates of Dallas, Texas, U.S.A. formally professor of agronomy from Shiraz University, Shiraz, Iran. R185 12/02/97

2 The soil of the experiment site was silty to clay loam. Soil analysis indicated a need for lime, N, P, and K. Lime in the form of calcium magnesium carbonate (Dolomite) was added to the soil of the experimental area at the rate of 0.5 kg per square meter (5 tons/ha) in March to raise the soil ph level. There were 3 levels of nitrogen; 0, 30, and 100 percent (142 kg/ha N = 100 percent, and 3 levels of ; 0, 1, and 2 liters per hectare. The sources of nitrogen, phosphorus, and potassium were formulations , and ammonium nitrate (34.5%). To ensure sufficient quantities of P and K in the soil of the experimental area 240 kg/ha P 2 O 5 and 240 kg K 2 O from the formulation and were added to the soil and raked in 3 weeks before transplanting the seedlings. Nitrogen fertilizer was added at the same time using formulation and 34.5 percent N ammonium nitrate. A 3 X 3 factorial design using 3 levels of nitrogen and 3 levels of comprising 9 treatments was used. The experiment was replicated 3 times giving a total of 27 plots. The 9 treatments were as follows, where N is nitrogen and AG denotes : A = 0-N, 0-AG B = 0-N, IL AG/ha C = 0-N, 2L AG/ha D = 30% N, 0-AG E = 30% N, 1L AG/ha F = 30% N, 2L AG/ha G = 100% N, 0-AG H = 100% N, IL AG/ha I = 100% N, 2L AG/ha was applied as 1L and 2L in 450 liters of water per hectare on 25 May 1981 about 3 weeks after transplanting, and when plants had 3-4 true leaves. The solution was sprayed over the foliage, on the soil around plants and in between rows. To ensure uniform growth at the early stages the plants were sprinkler irrigated whenever necessary. They were not irrigated from July 10 until harvest - after the 6-8 leaf stage) in order to study the effect of on drought tolerance of plants. There was a relatively long drought period (90 days) from 11 June to 9 September 1981, when the total rainfall was insufficient for normal growth of beet plants, and the experimental plots had to be irrigated. The total rainfall for this period (90 days) was 44.4 mm (1.75 inches) or an average of 14.8 mm (0.59 inches) per month (30 days). The range of distribution was from 0.1 mm to 17.8 mm ( inches) during this period. Consequently there was severe soil moisture deficit. In June, July, and August 1981 measurements for soil moisture content showed a deficit 4 of 51.6 mm (2.06 inches), mm (4.46 inches) and mm (6.16 inches) respectively. During the same period soil moisture deficit rose from 3.6 mm (0.14 inches) in the top 10 cm of soil on 11 June to mm on 9 September. The soil moisture deficit began to diminish from the figure of mm (6.68 inches) on the 9 September to 99.1 mm (3.96 inches) by 30 September, and eventually to 47.7 mm (1.90 inches) by 22 October when the sugar beet plots were harvested. The soil moisture deficit as determined by the Weather Station is the net water loss accumulated at the end of each week. A negative net water loss - excess rainfall - is assumed lost by drainage. The monthly value is correct at the end of the last complete week of the month. As indicated it was after 9 September that plots received relatively regular rainfall and the soil moisture deficit began to diminish. During this period of very low rainfall there was severe moisture stress in the soil and it was reflected in plots by various degrees of wilting, placid state of plants, browning of leaf edges and eventually desiccation and death of the older leaves. The severe effects of drought and moisture stress were most pronounced in plots not receiving especially those having higher percentage of nitrogen fertilizers. Considerable loss of older leaves was reflected in the new growth of younger leaves from the crown of plants severely affected by moisture stress. The rosette type of growth was pronounced after soaking rain in the second week of September. To evaluate drought tolerance of plants in each treatment, points were given depending on the number of dead, desiccated and yellow leaves and number of plants affected, as well as severity of moisture stress response by the plants, where 1 is the highest degree of tolerance to drought and 10 is the 1east degree of tolerance, showing various degrees up to complete wilting and point of permanent wilting. The data are analyzed for drought tolerance and are reported in the section of results. 4 Weather data is from Woodland Field, Sonning Farm, Crop Research Unit, Dept. of Agriculture & Horticulture, University of Reading, Reading, England. The Weather Station is the nearest Weather Recording station to the site of the experiment. 2

3 The middle row of each plot was harvested on 22 October Roots were washed, cleaned, weighed and the number of beets per plot was recorded. The tops were cleaned, weighed and a sample of 1 kg was taken from each plot for dry matter percent and yield. Root samples from plots were sliced to small 3-4 cm (1-1.5 inch) cubes and frozen within a few hours of harvest to prevent sucrose conversion and loss of beet weight. Sucrose percent was determined by the standard laboratory methods. Root samples were cut in cubes of 1-3 cubic centimeter size and frozen. They were then sent to the British Sugar Corporation's laboratories at Peterbrough for the percent sucrose and milliequivalent of per 100 gm of both beet and sugar of potassium, sodium and noxious nitrogen ( -amino N). These are the impurities. The procedure used for determining the percent sucrose consisted of passing the frozen slices of sugar beet through a Hobart chopper. This machine produces a mince-like material without any separation of juice from the sample and enables accurate sub-sampling to be achieved. A 26 g portion of beet was then taken for analysis and was macerated with basic lead acetate solution, in a Waring blender, to produce a filtrate suitable for determination of sugar content and impurities. Sucrose content and impurities were determined on duplicate samples from each plot. Potassium, sodium, and alpha-amino nitrogen as impurities were measured as milliequivalent per 100 gm of beet and sucrose by B.S.C. (British Sugar Corporation) Laboratories at Peterborough, England. Glutamine and nitrogen, as ammonium sulfate, were measured by Technicon Suquential Multi-Amino Acid Analyser (TSM) at the University of Reading. Glutamine and ammonium values are shown as UU mol (micromilliliter) per milliliter of filtrate of beets used for determination of percent sucrose. RESULTS Results from the analysis of data on beet yield, percent dry matter, total yield of dry matter, percent sucrose and other parameters measured are presented in Table 1. In this Table values for treatment G (100 percent nitrogen = 142 kg/ha N) is taken as 100 percent and values for other treatments are compared with it. In Table II total yield of tops (leaves and petioles), percent dry matter, total yield of dry matter per hectare of tops and other parameters measured are presented. In Table III impurities were measured on macerated beet roots samples and on sugar milliequivalent per 100 gm of beet root and sucrose, as well as on glutamine and ammonium as ammonium sulfate (NH 4 ) 2 SO 4. TABLE I: Yield of roots, percent dry matter, percent sucrose and other parameters measured of sugar beet experiment April-October 1981 at University of Reading Experimental Grounds, Reading, England Roots Yield T/ha Yield of roots DM T/ha Yield of Sugar T/ha No. plants per plot % % % % % % Treatments Control DM Control Control Sucrose Control A = 0-N, 0-Ag B = 0-N, 1L AG/ha C = 0-N, 2L AG/ha D = 30%, 0-AG E = 30% N, 1L-AG F = 30%, 2L AG/ha G = 100% N, 0-AG H = 100% N, 1L AG/ha I = 100% N, 2L AG/ha Wt root per plot % Control 3

4 TABLE II: Yield of tops, percent dry matter, and other parameters measured of sugar beet experiment April- May 1981, at the University of Reading Grounds, Reading, England Fresh tops T/ha % Dry Matter Yield of dry matter T/ha No. of plants per plot Wt. Of tops per plant % % % % Drought % Treatments Control Control Control Control tolerance Control A = 0-N, 0-AG B = 0-N, 1L AG/ha C = 0-N, 2L AG/ha D = 30% N, 0-AG E = 30% N, IL AG/ha F = 30% N, 2L AG/ha G = 100% N, 0-AG H = 100% N, 1L AG/ha I = 100% N, 2L AG/ha TABLE III: Impurities as milliequivalent of K, Na and amino nitrogen determined per 100 gm beet and sugar; and glutamine and ammonium content determined by TSM for sugar beet experiment at the University of Reading, Reading, England, April- May 1981 Per 100 gm Beet Per 100 gm Sugar Glutamine + NH 4 Total % % amino amino U mol U mol impurities/1000 ctrl purity of Treatments K Na nitrogen K Na nitrogen ml ml gms sugar sugar A = 0-N, 0-AG B = 0-N, 1L AG/ha C = 0-N, 2L AG/ha D = 30% N, 0-AG E = 30% N, IL AG/ha F = 30% N, 2L AG/ha G = 100% N, 0-AG H = 100% N, IL AG/ha I = 100% N, 2L AG/ha In Table IV statistical analysis of the yield of washed beet roots is presented. TABLE IV: Comparisons of means of treatments for yield of sugar beet roots Χ LSD at P =.05 for N levels = 5.07 T/ha LSD at P =.05 for N levels = 6.99 T/ha LSD at P =.05 for levels = 5.07 T/ha LSD at P =.01 for levels = 6.99 T/ha As is seen from Table IV there are highly significant and significant differences for means of treatments 30% nitrogen compared with 0 and 100% levels of nitrogen respectively. 30% nitrogen level produced significantly greater yield of beet roots than did 100% nitrogen level. There was a highly significant differences among levels irrespective of the level of nitrogen. levels produced highly significant differences compared with 0 level of. Application of 2 L/ha produced highly significant difference compared with 0 level of. The difference between treatment means of 1 L /ha and 0 level of /ha though not significant at P =.05 was significant at P =.1, which indicates that 1 L/ha was effective at a slightly lower level of probability. 4

5 In Table V data related to yield of tops are presented. TABLE V: Comparisons of means of treatments for yield of sugar beet tops Χ LSD at P =.05 for N levels = 6.58 T/ha LSD at P =.01 for N levels = 9.07 T/ha LSD at P =.05 for levels = 6.58 T/ha LSD at P =.01 for levels = 9.07 T/ha In Table V treatment means for nitrogen levels of 30% and 100% showed highly significant differences when compared with 0 level of nitrogen irrespective of the level of. On the other hand, treatment means of 1 L /ha and 2 L showed highly significant and significant differences respectively compared with 0 level of irrespective of the levels of nitrogen. There were no significant differences among treatment means of nitrogen levels, levels, replicates and nitrogen x (interaction) for percent dry matter of roots, percent dry matter of tops and percent sucrose. The data for total dry matter production of roots per hectare are presented in Table VI. TABLE VI: Comparisons of means of treatments for total dry matter yield of beet roots per hectare Χ LSD at P =.05 for N levels = 1.23 T/ha LSD at P =.01 for N levels = 1.69 T/ha LSD at P =.05 for levels = 1.23 T/ha LSD at P =.01 for levels = 1.69 T/ha From Table IV it is seen that there are highly significant differences among treatments of different nitrogen levels for total dry matter yield of roots per hectare. Means of nitrogen treatment levels of 30% nitrogen produced highly significant greater yield of total dry matter than did 100% and 0 levels of nitrogen respectively. levels produced highly significant differences among different levels irrespective of the levels of nitrogen. Means of treatments of 2 L /ha and 1 L /ha produced respectively highly significant and significantly greater yield of beet root dry matter per hectare than did 0 levels of. When total dry matter yield of tops per hectare was considered similar trends were noted. Data for dry matter yields are presented in Table VII. As Table VII shows, means of treatments 100% and 30% nitrogen levels produced respectively highly significantly and significantly greater yield of total dry matter of beet tops per hectare than did 0 levels of nitrogen. levels also produced highly significant total dry matter yield of beet tops per hectare, irrespective of the levels of nitrogen. Treatments means of 1 L /ha and 2 L /ha produced respectively highly significantly and significantly greater yield of dry matter of tops per hectare than did 0 levels of. 5

6 TABLE VII: Comparison of means of treatments for total dry matter yield of tops of sugar beets Χ LSD at P =.05 for N levels =.90 T/ha LSD at P =.01 for N levels = 1.24 T/ha LSD at P =.05 for =.90 T/ha LSD at P =.01 for = 1.24 T/ha Total yield of sugar/ha was analyzed statistically and the data are presented in Table VIII. TABLE VIII: Comparisons of means of treatments for total yield of sugar per hectare Χ LSD at P =.05 for N levels =.900 T/ha LSD at P =.01 for N levels = T/ha LSD at P =.05 for levels.900 T/ha LSD at P =.01 for levels T/ha As is seen in Table VIII comparisons of means for different nitrogen levels show highly significant differences f or nitrogen levels irrespective of the levels of used. Means of treatment 30% nitrogen showed significant and highly significant differences in yield of sugar per hectare compared with 100% and 0 level of nitrogen respectively. levels showed highly significant differences among means for total sugar production per hectare irrespective of the levels of nitrogen. Treatment means for 2L and 1L per hectare showed highly significant and significant differences respectively in yield of sugar per hectare compared with 0 level of. Sugar beet plants treated with at 1 and 2 liters per hectare showed remarkable drought tolerance during the period of soil severe moisture stress in July and August Points were given to indicate difference degrees of leaf, plant and plot wilting. The scores from 1 to 10 were used, 1 being the most tolerant of the drought and soil moisture stress, while 10 was the least tolerant of drought and soil moisture stress. Data are analyzed and presented in Table IX. TABLE IX: Comparisons of means of treatments for drought tolerance % N of sugar beet plants Χ LSD at P =.05 for N levels =.996 units LSD at P =.01 for N levels = units LSD at P =.05 for levels =.996 units LSD at P =.01 for levels = units 6

7 Table IX shows highly significant differences among treatments means for drought tolerance at different levels of nitrogen irrespective of the levels of. Means of treatments for 0 and 30% nitrogen showed highly significantly and significantly greater drought tolerance respectively compared with treatment means for 100% nitrogen. Treatment means for 0 levels of nitrogen showed significantly greater drought tolerance compared with 30% nitrogen level. levels showed highly significant difference treatment means at different levels of application irrespective of the levels of nitrogen used. Treatment means of 1 and 2 liters of respectively showed highly significant differences (greater) compared with 0 level of. There was a significant difference in drought tolerance between means of treatments for 2 L /ha compared with 1 L /ha respectively. There was a highly significant interaction between levels of and levels of nitrogen for drought tolerance. Treatment means receiving 1 and 2 liters of and 30% nitrogen respectively showed highly significant drought tolerance compared with treatment means having 30% nitrogen and no. Even at the higher nitrogen level of 100% treatment means receiving 2 L /ha showed a significant increase in drought tolerance compared with treatment means having no. Impurities were determined on the filtrate from macerated beet and sugar and include potassium sodium and alpha amino nitrogen, calculated as milliequivalent per 100 gm. of beet and sugar. The data for each impurity is analyzed and are presented in the following Tables. TABLE X: Comparisons of means of treatments for mg of K/100 gm of beet root Χ LSD = P =.05 for N levels =.409 meq/100 gm beet root LSD = P =.01 for N levels =.563 meq/100 gm beet root LSD = P =.05 for levels =.409 meq/100 gm beet root LSD = P =.01 for levels =.563 meq/100 gm beet root Table X shows there are highly significant differences of meq of K/100 gm beet root for different levels of nitrogen irrespective of the level of. Treatment means of 30% nitrogen showed highly significantly greater meq of K/100 gm beet root than did treatment means for 0 levels of nitrogen. levels did not show any significant differences among treatment means. TABLE XI: Comparisons of means of treatments for meq Na/100 gm beet root Χ LSD at P =.05 for N levels = meq Na/100 gm beet root LSD at P =.01 for N levels = meq Na/100 gm beet root LSD at P =.05 for levels = meq Na/100 gm beet root LSD at P =.01 for levels = meq Na/100 gm beet root In Table XI it is seen that there are highly significant differences among means for meq of Na/100 gm beet root among different levels of nitrogen irrespective of the level of. Means of treatments 0 and 30% nitrogen showed highly significantly and significantly greater milliequivalent sodium per 100 gm beet root than did means 7

8 of treatments receiving 100% nitrogen. levels did not show any significant differences among treatment means. An important component of impurities is nitrogen measured in terms of alpha amino nitrogen. Data for the analysis of the millequivalent of alpha amino nitrogen per 100 gm of beet root are presented in Table XII. TABLE XII: Comparison of means of treatments for meq alpha amino nitrogen/100 gm beet root Χ LSD at P =.05 for N levels =.587 meq/100 gm beet root LSD at P =.01 for N levels =.809 meq/100 gm beet root LSD at P =.05 for levels =.581 meq/100 gm beet root LSD at P =.01 for levels =.809 meq/100 gm beet root Table XII shows there are highly significant differences in meq of alpha amino nitrogen for different levels of nitrogen irrespective of the levels of. Means of treatments 100% nitrogen showed a highly significant differences in meq alpha amino N compared with means of treatments for 0 and 30% nitrogen respectively. Although means of treatment 30% nitrogen were not significant at P =.05 for meq of alpha amino N compared with 0 level of nitrogen, there was a significant difference at P =.01. Impurities measured on refined sugar are presented in the following Tables. TABLE XIII: Comparisons of means of treatments for meq k/100 gm sugar Χ LSD at P =.05 for N levels = 2.39 meq K/100 gm sugar LSD at P =.01 for N levels = 3.35 meq K/100 gm sugar LSD at P =.05 for levels = 2.39 meq K/100 gm sugar LSD at P =.01 for levels = 3.35 meq K/100 gm sugar In Table XIII it is seen that there are highly significant differences among treatment means for nitrogen levels in respect of meq K/100 gm sugar. Means of treatment 30% nitrogen showed a highly significant increase in meq of K/100 gm sugar compared with treatment means for 0 and 100% nitrogen respectively. Means of treatment 100% nitrogen showed a significant increase in meq of K/100 sugar compared with treatment means for 0 level of nitrogen. levels did not show any significant difference among treatment means. Replicates showed significant differences to meq of K/100 gm sugar. There was a significant difference between means of replicate I and replicate III for meq K/100 gm sugar as is shown below. LSD Replicate Means Means Differences I I & 11 = 3.89* II I & III = 3.12 NS III II & III = 0.77 NS *Significant difference at P =.05 8

9 These differences indicate differential absorption of K cations by the beet roots. Data from milliequivalent of sodium per 100 gm of sugar are presented in Table XIV. TABLE XIV: Comparisons of means of treatments for meq Na/100 gm sugar Χ LSD at P.05 for N levels =.54 meq Na/100 gm sugar LSD at P.01 for N levels =.74 meq Na/100 gm sugar LSD at P.05 for levels =.54 meq Na/100 gm sugar LSD at P.01 for levels =.74 meq Na/100 gm sugar In Table XIV there are highly significant differences among treatment means of N levels for meq Na/100 gm sugar. Treatment means of 0 percent nitrogen showed highly significant and significant increase of meq Na/100 gm sugar over treatment means for 100% and 30% nitrogen respectively. levels did not show any significant differences among treatment means. Alpha amino nitrogen was determined for sugar and the analyzed data are presented in Table XV. TABLE XV: Comparison of means of treatments for alpha amino N/100 gm sugar Χ LSD at P =.05 for N levels = 3.61 meq alpha amino N/100 gm sugar LSD at P =.01 for N levels = 4.97 meq alpha amino N/100 gm sugar LSD at P =.05 for levels = 3.61 meq alpha amino N/100 gm sugar LSD at P =.01 for levels = 4.97 meq alpha amino N/100 gm sugar As is shown in Table XV there are highly significant differences among treatment means of N levels for meq alpha nitrogen/100 gm sugar. Means of treatment 100% nitrogen showed highly significant increases in alpha amino nitrogen per 100 gm. sugar compared with treatment means for 0 and 30% nitrogen. Means of treatment 30% nitrogen showed a significant increase in alpha amino nitrogen per 100 gm sugar compared with treatment means for 0 percent nitrogen. levels did not show any significant differences among treatment means. The nitrogen content of beets in the form of ammonia was measured as ammonium sulfate (NH 4 ) 2 SO 4, on the filtrate used for determining the percent sucrose. Both ammonia sulfate and glutamine were measured as micromilliliters per milliliter of the filtrate. The data analyzed for each treatment is presented in Table III. There were no significant differences among treatment means for ammonia at all levels of nitrogen,, replicates and nitrogen x (interaction). There were highly significant differences for glutamine content among replicates, and among nitrogen levels. The means of treatments for replicates I showed highly significant increases of glutamine compared with means of treatments for replicates II and III as are shown below: 9

10 LSD Replicate Means Means Differences I I & II = ** II I & III =1.0620** III II & III = NS This may be due to the residual effect of the previous crop grown on part of the experimental site. Data analyzed for the contents of glutamine of beets in each treatment are presented in Table XVI. TABLE XVI: Comparisons of means treatments of glutamine for micromilliliter per milliliter of beet filtrate Χ LSD at P =.05 for N levels =.450 uml/ml LSD at P =.01 for N levels =.620 uml/ml LSD at P =.05 for levels =.450 uml/ml LSD at P =.01 for levels =.620 uml/ml Table XVI shows highly significant differences among treatment means for glutamine contents at different levels of nitrogen. Treatment means receiving 100 percent nitrogen showed a highly significant increase in glutamine content compared with treatments receiving 0 and 30 percent nitrogen respectively. There was a significant increase in glutamine content for means of treatments receiving 30 percent nitrogen compared with the means of treatments 0 percent nitrogen. levels showed no significant differences among treatment means for glutamine content. There were no significant differences among means for nitrogen x (interaction). Total impurities per 100 gm sugar are calculated according to formula on page 7 and analyzed statistically. Percent purity is the grams of impurities subtracted from 100 gm of sugar. Data for these analyses are presented in Tables XVIII and XIX respectively. TABLE XVII: Comparisons Of Means Of Treatments For Grams Of Impurities/100 Gm Sugar Χ LSD at P =.05 for N levels =.62 gm/100 gm sugar LSD at P =.01 for N levels =.85 gm/100 gm sugar LSD at P =.05 for levels =.62 gm/100 gm sugar LSD at P =.01 for levels =.85 gm/100 gm sugar Table XVII shows highly significant increases of impurities for means of treatments having 100 and 30 percent nitrogen compared with treatment means having 0 percent nitrogen. Means of treatments having 30 percent nitrogen showed a significant increase in percent total impurities compared with means for 100 percent nitrogen. levels did not show any significant difference in percent total impurities. 10

11 TABLE XVIII: Comparisons Of Means Of Treatments For Percent Purity Of Sugar Χ LSD at P =.05 for N levels =.62 percent LSD at P =.01 for N levels =.85 percent LSD at P =.05 for levels =.62 percent LSD at P =.01 for levels =.85 percent Table XVIII shows highly significant increase in percent of purity of means of treatment 0 percent nitrogen, compared with means of treatments for 100 and 30 percent nitrogen. Treatment means for 30 percent nitrogen showed significant increase in percent purity compared with means of treatments for 100 percent nitrogen. CONCLUSION Data presented in Tables I - XVIII clearly show the combined effects of nitrogen and on the parameters measured in sugar beets. Application of only 30 percent (45 kg/ha N) of the recommended rate of nitrogen (150 kg/ha N) with 1 or 2 liters of /ha produced a significant increase in yield of beet roots compared with treatments receiving 100 percent nitrogen application (142 kg/ha N). Part of the increase in the yield of roots may be attributed to the residual nitrogen, already in the soil, but a major contributor to the yield of beet roots at the 30 percent nitrogen level has been application of 1 and 2 liters of per hectare respectively. This is supported by the evidence that 2 liters of /ha produced a highly significant increase in yield of beet roots over the 0 level of while the increase in yield of beet roots of 1 liter/ha was also significant. When the data for yield of tops were examined, highly significant increases were noted in the fresh weight of tops for 30 percent and 100 percent nitrogen treatments compared with 0 percent nitrogen treatments. applied at 1 and 2 litres per hectare produced highly significant and significant increases respectively over treatment means not receiving. It is quite evident that application at both levels of 1L and 2 L/ha produced highly significant and significant yield increases compared with the treatments not receiving. Further evidence in this connection comes from the statistical data analyzed for the yield of dry matter of roots and tops. Application of I and 2 liters of /ha produced highly significant and significant yield increases in total dry matter yield of roots and tops over the treatments where no was applied. The evidence clearly shows that increase in the fresh weight of roots and tops was not accompanied by a reduction in total dry matter production, moreover, the percent dry matter for roots and tops showed no significant difference for any of the treatments and thus extra yield of roots and tops produced proportionate yield of dry matter. Nitrogen levels of 30 percent produced highly significant and significant increases in the yield of root dry matter over 0 percent and 100 percent nitrogen levels respectively while 100 and 30 percent nitrogen levels produced highly significant increases in yield of dry matter of tops respectively compared with 0 percent levels of nitrogen. The situation of percent dry matter is also true for percent sucrose. There were no significant differences among means of different treatments for sucrose content. As a result increase in yield of roots was reflected in a proportionate and greater increase in the yield of sugar per hectare. It is interesting to note that 30 percent level of nitrogen produced highly significant and significant increases in the yield of sugar per hectare compared with 0 and 100 percent nitrogen levels respectively. The low levels of nitrogen appear to have produced optimal effect in sugar accumulation in beets at the end of the season. Higher 17 relative sugar percent plus considerably greater increase in yield of roots has produced greater tonnage of sugar per hectare. it is also the lower yield of roots in treatments receiving 100% nitrogen that have resulted in significantly reduced yield of sugar per hectare compared with treatments receiving 30% nitrogen. 11

12 A unique feature of the beet plants response to was in their reaction to long periods of drought experienced from 11 June- 9 September 1981 (44.4 mm = 1.75" rainfall). At 0 and 30% nitrogen application, -treated plots did not show the slightest symptoms of soil moisture stress, leaf wilting, darkening of leaf color, progressive yellowing, browning and eventually death of the older leaves when combined with 1 and 2 L /ha respectively. On the other hand, beet plants in plots receiving 100 percent nitrogen showed symptoms of soi1 moisture stress (soil moisture deficit of mm, 6.16", in August and mm, 6.68" in September) reflected in pronounced wilting of the leaves, yellowing, browning of the edges, desiccation and death of the older as well as some of the younger leaves, to the extent that a new rosette of leaves appeared in the center of the affected plants after the first soaking rain in September These symptoms were also seen in plots receiving 100 percent nitrogen plus 1 liter of per hectare but to a much lesser extent. 100 percent nitrogen plots using 2 liters of per hectare showed these symptoms even to a much lesser degree than did 100 percent nitrogen plots plus 1 liter /ha. These reactions indicate that the tolerance induced in plants to drought conditions is, within limits, inversely related to the amount of nitrogen used and the status of N as NH 4 + or NO 3 -N in the soil. It appears that the greater the soil contents of these two cations and anions the lesser is the tolerance of -treated plants to long periods of relative drought. Evidence from the data of nitrogen x (interaction) provides support. Plants in treatments have 30% nitrogen with 1 and 2 liters /ha showed the highest tolerance to drought conditions followed by plants in treatments having 0% nitrogen plus 2L and 1L /ha respectively. Moreover plants in plots receiving no showed significantly lower tolerance to drought and soil moisture stress. Even plants in treatments at 0% nitrogen level which received no nitrogen fertilizer and the soil had a nitrogen fertilizer content of 45 kg/ha N below that of 30% nitrogen treatments with 1 or 2 L /ha showed severe symptoms of wilting. The highest degree of tolerance to soil moisture stress and drought was shown by plants in plot C where 2 L /ha was used with 0% nitrogen. Apparently a relatively high level of made use of the residual soil nitrogen and induced highest degree of tolerance to drought conditions and soil moisture stress. Analysis of impurities showed highest absorption of meq. of K per 100 mm of beets and sugars in treatments receiving 30% nitrogen compared with treatments have 0 and 100% nitrogen, whereas sodium absorption was highest in treatments have 0% nitrogen compared with treatments receiving 30 and 100 percent nitrogen in both the beet roots and the sugar extracted. The concentration of alpha amino nitrogen affects beet qua1ity and ensuing processing. Alpha amino nitrogen, however, showed to be the highest in amount in terms of milliequivalent per 100 gm of beet root and sugar in treatments receiving 100% nitrogen compared with treatments receiving 30 and 0 percent nitrogen, while 30% nitrogen treatments showed significantly greater amounts of alpha amino nitrogen per 100 gm of beet pulp and sugar compared with 0 percent nitrogen. The relationship between potassium and nitrogen levels shows an attempt by plants to maintain the ionic balance when nitrogen in plants reaches a certain level and passes beyond a certain limit. The relationship of sodium and nitrogen in the data analyzed follows the normal pattern of sodium uptake with considerable variation in relation to the amount of nitrogen available and the amount of nitrogen absorbed by the plant. The concentration of glutamine and ammonia nitrogen present in beet roots influences the quality of the beet root and the molassogenic tendency of beet juice. Considerable experimental evidence indicates that high concentrations of glutamine and ammonia nitrogen decrease the quality of beet and the process of sugar extraction that follows. In our experiment there were no significant differences in glutamine content among treatment means for levels, and nitrogen x (interaction). There were highly significant differences among nitrogen levels for the glutamine content of roots. Relatively high glutamine contents of treatments have 100 percent nitrogen compared with treatments having 0 and 30% nitrogen may be attributed to the higher uptake of nitrogen by plants on plots of 100% nitrogen treatment. Moreover, there was a significant increase in the glutamine content of 30% nitrogen treatments compared with treatments having 0 percent nitrogen. In conclusion, it is of especial interest and significance to note that levels and treatment means did not show any significant differences in content of impurities, such as potassium, sodium, alpha amino nitrogen, glutamine and ammonia nitrogen. This is important both from the point of view of sugar accumulation in roots and purity of juice in subsequent sugar extraction. In this connection percent total impurities per 100 of sugar and percent purity (Tables XVII and XVIII) show quite clearly that as the level of nitrogen increased from 0 to 30 and 12

13 to 100 percent there was a significant increase in grams of impurities per 100 gm sugar and a significant decrease in percent impurity. 13