Sugarbeet As Influenced by Row Width, Nitrogen Fertilization, and Planting Date 1

Transcription

1 Sugarbeet As Influenced by Ro Width, Nitrogen Fertilization, and Planting Date 1 M. A. DILLON AND "\IV. R. SCHMEHL" Received jvl /","liration October 2, 1971 In temperate climates the leaf canopy of a sugarbeet crop may not cover the soil surface for more than one-half the time beteen planting and harvest. The slov" development of leaf area during the spring is a critical limitation in sugarbeet production, since the total production of dry matter depends on the size of the photosynthetic system (ieaf area), the duration of the leaf area, and its relation to the seasonal income of solar radiation (8). 'IVhere nutrients and moisture are optimum, more emphasis should be p;aced on management practices that ill increase the leaf canopy early in the groing season. Early season groth of sugarbeets can be increased by several practices. Dillon et al (5) report that transplanting and the use of polyethylene cover over fie!d-p~anted sugarbeets in ~reased sucrose yields from 25 to 4 %. The objective of our research as to study the influence of nitrogen fertilizer, plant population, and planting date on early groth and the relationship to final yields. Methods and Materials Sugarbeets ere gtq1.vn under irrigation in to field experiments at the Colorado State Pniversity Research Center near Fort Collins on a calcareous, non-saline Nunn clay loam ith ro spacing and planting date as variables. Nitrogen fertilizer as broadcast as ammonium nitrate and harroed into the soil prior to pl anting. Phosphorus fertilizer as applied uniformly to provide an adequate level of this nutrient. Spring heat preceded the 1968 experiment and dry beans the 1969 experiment. The 1968 experiment compared three ro idths at to nitrogen levels and to planting dates in a split-block design ith 3 replications. The planting dates ere April 9,lOd i\lay 2. Nitrogen fertilizer levels ere 4 and 15 lbs. N per acre. Ro idths and accompanying plant populations to the nearest 1 ere: 1) 22-in ros ith 28,5 pl,lllts per acre, 2) alternating 1 Published ith the approval of the Dire<:tor of the Col orado State University Experiment Station as Scientific Series Paper No This study as supported by the Agricul. tural R c~('a n1t Sen'icc, U. S. Department or Agriculture, lln :.lcr Cooperative Agreement No (3'1) administered by the Plant Science Research Division, Beltsville. Maryland. 3 Former Graduate R esearch Assistant (no at Tribune Branch Experiment Station. Tribune, Kansas); and Professor of Agronomy. Colorado State University. Fort Collins, Colorado. 8521, respectively.

2 586 JOURNAL 1' THE A. S. S. B. T. II-in and 22-ill ros ith 38, plants per acre, and 3) alternating II-in and 33-in ros ith 28,5 plants per acre. The plant spacing in the ro remained constant at 1 inches. In the 1969 experiment, there ere three ro 'idths at three nitrogen levels and to planting dates in a split-split plot design. Planting dates ere April 4 and May 14.!'iitrogen fertilizer levels ere, GO, and 12 Ibs. N per acre. Ro idths and accompanying plant populations ere: I) 22-in ros ith 28,:) plants per acre, 2) alternating 18-in and 22-in ros ith 31,4 plants per acre, and 3) alternating 13-in and 22-in rov"s ith 35,8 plants per acre. Nitrogen fertilizer level, the main plot, as split for ro idth, and planting date as the Sll b-sub-plot. There ere four replications to give a total of 72 plots. In 1968, the Leets in 15 ft. of ro ere harvested approximately every to eeks beginning June 18. In 1969, the beets in 2 ft. of ro ere harvested approximately every four eeks beginning June 3. The final harvest in 1969 as 3 feet of ro. There ere a total of nine harvests in 1968 and four harvests in Alternate ros ere harvested to maintain uniform competition throughout the season. Leaf area index (LAI) as determined by the punch method described by Campbell and Viets (2). Sucrose content as determined on the brei by a modification of the method outlined in A.O.A.c. (1). Purity of the thin juices as determined by the method of Carruthers and Oldfield (3). Recoverable sucrose percentage as calculated from the sucrose content and thin juice purity by assuming a standard factory loss of.3% and a molasses purity of 62.5% (4). Final Harvest Results Results and Discussion The October 14 and October 28 harvests ere combined for statistical analysis in the 1968 experiment. There,,,,ere no maineffect differences ben-veen harvests significant at the 1% level, nor ere there any interactions beteen harvests or ithin the combined harvests. Results of the combined analysis are given in 'fable 1 for yield and quality, for ro idth and plantingdate effects. :'-J itrogen fertilizer level had no significant effect on any of the yield or quality characteristics shon in Table 1. The field design gave greatest precision to the ro spacing and small differences in yield and quality due to nitrogen treatments ere not significant at the 1% level. Petiole nitrate analyses indicated that all treatments had adequate supplies of availabll nitrogen through September.

3 VOL. 16, No.7, OCTOBER Rovv idth had a significant effect on both root yield and recoverable sucrose (Table 1). The significance resulted from loer yields of roots and recoverable sucrose from the 11 X 33-in ro\vs than for the 22-in ros, even though both treatments had the same number of plants per acre. Sucrose content and purity also tended to be depressed by this spacing, although these differences ere not significant. The 11 X 22-in ro spacing, ith one-third more plants, produced about the same yield as the 22-in spacing. Table I. E(fcet of ro idth and planting date on yield and quality of sugarbeets, October 14 and 28 barvests combined, Root Yield Sucrose Purit), Recoverable Treatment T / A % % Sucrose T/A Ro idth 1 ~2-jn II X 22 io II X 33-in 16.7" ' Planting' date April # 2.93' May Plants per acre: 22-in rolvs 28,5; II X 22-;n ros 38,; 11 X 33-in ros 28,5. #, - DifEers frolll 22-in ro spacing or from late plantillg at 1% (#) or 5% () levels oe significance, respectively. The early planting increased purity from 9.9% to 93.1 % and had the same trend for root yield and sucrose. The combined planting-date effects of root yield, sucrose content, and purity resuj ted in a significantly greater yield of recoverable sucrose for the early planting. The average yield as 2.93 tons of recoverable sucrose per acre for the April 9 planting compared to 2.54 tons per acre for the May 2 planting. Increased sugarbeet yield and quality from early planting have been reported by Schmehl, et a!. (9) in Colorado and by Hull and Webb (7) in England. The effects of ro idth and planting date on the yield of the final harvest in 1969 are presented in Table 2. Again, as in 1968, the application of nitrogen fertilizer had little effect on root yield or production of recoverable sucrose. Percentage sucrose, hoever, as about 3% loer at harvest for all treatments in 1969 than in Since chemical analysis shoed that the nitrogen content of the petioles as about the same in September each year, the lo sucrose in 1969 as attributed to cool, et eather during October. There ere 4 inches of precipitation during the first to eeks of October beginning ith rain and sno on October 3. The plants ere covered ith sno much of this to-eek period. The mean air temperature for October as 39.5"F and the roots ere frozen at harvest.

4 388 JOCRNAL OF THE A. S. S. R. T. T able 2. EUect of ro idth and planting date on root yield and qua!ity of sugar beers, November 1, Root Yield Sun'ose Purity Recove"able Treatlnent T /A % (/' Sucrose T /A Ro ' idth! 22 ;n "4 18 X 22-in b6 13 X 22 in # '1;lnting' clate April " 14.9.tt May Plants per acre: 22 in ros 28,:;; 18 X 22 in ro\,\'$ 31,4; 13 X 22 in ros 35,8. #. '. Differs from 22-in ro idth or from lale planting at 1% (#) or 5% ( ) level s of significance, respectively. Increasing the number of plants per acre ith closer ros did not affect root yield or recoverable sucrose. The closest ro spacing (13 X 22-in ros) did increase the sucrose contenl Slightly (1 % level), but the effect as not large enough to increase recoverable sucrose. Although other ro idths might have been more advantageous, results of Hills, et al." indicate that stands of 28,5 plants per acre are close to optimum for several different ro idths. Goodman (6) considers that under the conditions of southern England, 3, plants per acre are sufficient to fill the available space and, given abundant ater and nutrients, ill produce maximum yields. Thus, it appears that generall y there is no advantage to ros closer th;ln 22 inches hen the in-ro spacing- is about 1 inches. Early planting significantly increased final root yield again in Beets planted April 4 averaged 24.3 tons per acre compared to IS.1 for beets planted May 14. Early planting also in' creased the sucrose content from 14.5 to 14.9%. Thus, a delay in planting from April 4 to May 14 reduced the yield of recoverable sucrose from 3.2 to 2.18 tons per acre. The advantage for early planting as much greater in 1969 than in the previous. year, but it should be noted that there as a 4-day difference" beteen planting dates in 1969 compared to 23 days in f~arly Groth Leaf areas and root yields in June and early July are presented in Tables 3 and 4 for 1968 and 1969, respectively. There as no early groth response to nitrogen fertilization, nor ere there any significant interactions ith nitrogen either year. Therefore, the results are averaged over nitrogen levels for the main effects of planting date and ro idth. " Hills, f. J., T. M. Little, and G. M. Worker. Sugarbeet spacing and in roll' competition. Presen ted a t the J6th General "feeling of the Am. Soc. Sligar Beet Techno!., Denver, Feh , 197.

5 VOL. 16, ~o. 7, OCTOBER For the June 18 sampling in 1968, planting in II X 22-in ros significantly increased early LAI approximately in proportion to the increase in plant population. The 11 X 33-in and the 22-in ro idths both ith the same plant population had about the same LAI in mid-june. By July 2, the effect of ro idth on LAI as no longer significant Crable 3). Table 3. The effect of ro idth and planting' date on leaf area index (LAI) and rool yield in June and early July, June 18 July 2 Treatolent LAI Root yield, T / A LAI Root yield, T/A Ro' idth l 22 in II X 22 in.61# II X 33 in # Planting date \pril 9.76'.37 ' 2.38' 3.75' May Plants per acre: 22-in ro\vs 28.5; 11 X 22 in ros 38,; 11 X 33 in ros 28,5. #,. Differs from 22 in ro idth or from late planting at 17, (#) or 5% ( ) levels of Significance, respecth cly. The first sample date in 1969 as June 3. By this date, ro idth had no significant effect on either leaf area or root yield (Table 4). Table.1. The effect of ro idth and planting date on leaf a.rea index (LAI) and root yield, June 3, 1969, Treatluent LAI Root yield, T / A Ro idth 1 22 in X 22 in X 22-in Planting date April 4.95'.73' Ma) Plants per acre; 22 in ros. 28,5; 18 X 22 in ros - 31,4; 13 X 22 in ros - 35,8. Differs [rom late planting' at 5% levej of significance. Planting date had a significant effect on early groth in both years of the experiment. Delay in planting from April 9 to May 2 in 1968 reduced the mean LAI in June from.67 to.27 and also reduced root yield in June from.37 to.11 tons per acre (Tahle 3). In 19fi9, delayed planting reduced the LAI on.june 3 from.96 to.12 and reduced root yield from.73 to.;) tons per acre (Table 4). Thus, the April plantings produced larger leaf canopies earlier in the season hich ould increase light interception and efficiency in the use of solar radiation.

6 59 JOURNAL OF THE A. S. S. B. T. Seasonal Leaf Area and Root Yield The effects of planting date on leaf area during 1968 and 1969 are presented in Figure 1. Total solar radiation averaged for to-eek intervals is given in the same figure. For both 1968 and 1969, the beets planted in April produced a larger leaf area early in the season and throughout the year, although relative differences ere small later in the season. Although early leaf areas ere less for the :Vlay planting, maximum LAl for botb April and May plantings ere attained about the same date each year. The maxima in 1968 ere reached about a month sooner than in 1969, caused possibly by greater solar radiation during this early period in 1969 (Fig. 1) or by higher petiole nitrate (41 vs 56 ppm NOs-N) in z 6 i= <!~ > <! 5 ::" :::",... <! E 4...J<.)... (f)_...j 3 <! <.) I-~ ~ 2 ( ) RADIATION "'1968 <'> <!...J 1968 PLANTING DATE 3 x z 2 <! W ::: <! LL <! W...J I April 9} 1968 May 2 o April ~ 1969 o May I (b) APR MAY JUN JU L AUG SEP OCT MONTH Figure lao Total daily solar radiation averaged for to-,~,e/::k intervals for 1968 and 1969 groing seasons. Figure lb. Effect of planting date on seasonal leaf are" index, 19G8 and 1969.

7 VOL. 16, No.7, OCTOBER IY7 1.'}9 1 The influence of ro idth on LAI is shon in Figure 2. As noted previously, differences among ro spacings ere not significant at the.) % level for either year in late June or early July (Tables 3 and 4). By early August, hoever, the 11 X 22-in ro spacing in 1968 had a significantly greater leaf area than the other treatments (Fig. 2). In 1969 differences among rovv-idth treatments ere small throughout the season. ROW WIDTH POPULATION 22 in 2851 II I I x '" I I x in x /::, 13 x rl...j 4 x 3 z 2 :: LL...J I I JUN JUL AUG SEP OCT MONTH Figur,e 2. Effect of ro spacing on seasonal leaf area index, 1968 and The effects of nitrogen fertilization on LAI during the season are summarized in Figure 3. Rates of nitrogen had little effect on LAI until August and September in Nitrogen effects ere not significant in 1969, but the trends ere similar. 'When LAI for each harves t ere correlated ith final root yield, correlations ere highest for the July 2 sampling in 1968 (r =.55, df = 1) and for June 3 in 1969 (r =.92, df = 16). Thereafter, correlation of LAI from later harvests ith final root yield decreased as the season advanced. Thus, variations in leaf area early in the season had a greater effect on final root yield than did a comparable difference in leaf area at a later date.

8 JOURNAL OF THE A. S. S. B. T.... : NITROGEN LEVEL 4 IbS/A} Ibs/A o Ibs/A t::, 6 Ibs/A } 1969 o 12 Ibs/A 1969 x 5 o z 2 ::: 3 l.l Figure 3. and L- ~ -L L- ~ ~O JUN JUL AUG SEP OCT MONTH Effect of nitrogen fertilization on leaf area index, 19G8 The time of leaf area presentation is as important as the total leaf area, especially 'hen root yield is considered. The only treatment increasing final yields in these experiments as planting date hich increased leaf area in June and early July. Although the nitrogen and ro spacing treatments increased leaf area in August and September, these treatments did not increase final root yields or recoverable sucrose (Tables 1 and 2) and the II X 33-in ros decreased root and sucrose yields in Planting date as the only treatment, other than the 11 X 33-in ro spacing, that significantly affected the seasonal root groth pattern and final yield. The effect of planting date on root gro'th shon in Figure 4 is similar for the to years. The advantage of the early planting as greater in 1969, probably because of a greater interval beteen the to planting dates. The early planting gained an advantage in root yield by early July hich as maintained to the end of the season. More than 8% of the difference in final root yield resulting from planting date as attained prior to August 1st of each year.

9 VOL. 16, No.7, OCTOllER 1971 PLANTING DATE Q) II Apri I 9 }1968 May 2 A p ri14} May 14 2 ~ 15 "' If) c: J >= f :: 5 Figure JUN JUL AUG SEP OCT NOV MONTH Effect of planting date on seasonal root yieids, 1968 and The resul ts indicate that cuitural practices that do not increase LAI before early July probably ill not increase sucrose production in temperate climates. This follos from results of these and other experiments (5, 1) hich sho that leaf area is the limiting factor early in the season, but that solar radiation generally is the factor limiting gtoth after about mid-july 'hen the full leaf canopy is developed. Summary Field experiments ere conducted to determine the influence of ro spacing, nitrogen fertilization and planting date on gtoth and yield of sugarbeets. The plants ere thinned to a uniform 1-in spacing in the ro for beteen-ro distances of 11 X 22 (alternate 11 and 22 in beteen ros), 13 X 22, 18 X 22, 11 X 33, and 22 in. The closer ro spacings had only a small effect on early season groth, but did increase the leaf area in August or Septem ber. Final yields of roots and sucrose, hoever, 'ere not increased by ros closer than 22-in, and 11 X 33-in spacing reduced yields of roots and sucrose. :"J itrogen fertilizer had no effect on the early groth of sugarbeets in these experiments, but it did increase the L,\I in August and September and reduce final root quality. There as little effect of nitrogen on final yield of recoverable sucrose.

10 594 JOURNAL OF THE A. S. S. B. T. Planting date "vas the only treatment hich had a substantial deect on early-season leaf area and final recoverable sucrose. The earlier planting dates resulted in a closed leaf canopy sooner in the season, and the increase in early top gtoth as accompanied by an increase in yield of roots. About 8% of the advantage in final root yield from early planting as accrued by the end of July. Light interception and quite probably the efficiency in use of sunlight ere enhanced by the early planting because leaf area as increased at a time hen LAI as relatively lo and solar radiation as high. Literature Cited (I) :\..O.A.C Official M e thods of A rill i),s!s. Association of Olficial\gricultural Chemists, 9tll Edition. Washington, D.C. (2) CAMPBELL, R. E., and F. G. VIETS, JR Yield and sligar production by sugar beets as affected by leaf area variations induced by stand density,md nitrogen fertilization. Ag,on. J. 59: (3) CARRLlI-IERS, A., and J. F. T. OLDFIELD Methods fo. tile assessment of beet quality. 1. Purity determination using a clarified extract from brei. lnt. Sugar J. 63: (4) DEXTER, S. T., M. G. FRAKES, and F. W. SNYDER A rapid and practical method of determining extractable hite sugar as m ay be applied to the evaluation of agronomic practices and groer cleliveries in the sugar beet industry. J.. \mer. Soc. Sugar Beet Techno!' 14:433-4.~4. (5) DILLON,:VI..\., B. D. MCCASLI N, and YV. R. SCHM.EHL Effect of transplating and plastic cover groth of sugar beets. Agron. J. 6'J (6) GOOD;\'IA N, P. J Effect of varying pl an t population on groth and yield of sugar beets. Agric. Prog. 41:82-1. (7) HULL, R., and D. J. WEllE Plant spacing. Rothamsted Report (or pp (8) IVI1\'$, J. D., and P. M. BRE MER Groth studies ith the sugar beet crop. Agric. Prog. 41 : (9) SCHMEHl., '\tv. R., R. FI NKNER, and J. SWINK Effect of nitrogen fertilization on yield and quality of sugar beets. J. Amer. Soc. Sugar Beet Techno!' 12: (1) STORER, K. R., W. R. SCHMEHL, allll R. J. H ECKER Quantitative groth studies ith sugarbeets, Bela vulgaris. J. Amer. Soc. Sugar Beet Technol. 15: