Relation between air temperature and length of vegetation period of potato crops.

Transcription

1 Mazurczyk W., Lutomirska B. and Wierzbicka A. Plant Breeding and Acclimatization Institute (IHAR) Research Division at Jadwisin Relation between air temperature and length of vegetation period of potato crops. ABSTRACT On the basis of multiannual field experiment conducted in Central Poland the relation between the air temperature sum (TSUM) and the length of vegetation period (Lv) of potato crops is described. It is shown that air temperature has significant influence on the duration of vegetation. The exponential equations describing relationship between Lv and TSUM are formulated for three maturity groups of potato crops: early, medium and late. The data sets of Lv and TSUM with their descriptive statistics for these potato groups are given as well. Key words: potato, air temperature, vegetation length. INTRODUCTION Temperature is one of the most important variables effecting the plant environment. It impacts on crop growth and yield in different ways. Photosynthesis, respiration, organs initiation and their relative growth, dry matter production and its distribution are dependent on temperature (Ewing et all, 1990; Keulen and Wolf, 1986; MacKerron and Waister, 1985; Montheith, 1981; Ng and Loomis, 1984; Squire,1995). A crop passes through successive phenological development stages. The length of these stages depends on the development rate which is modified by temperature. The aim of this study was to quantify the relationship between the air temperature and the length of vegetation period, from emergence till canopy death, of potato crops grown in Central Poland for many years. MATERIAL AND METHODS Potato crops were grown on light loamy sand at Experimental Station in Jadwisin near Warsaw. Each year between 1974 and 2000 (except 1981) the average length of growth period (Lv), from emergence till canopy death, was estimated for 3 groups of potato cultivars: early, medium and late. In Poland potato varieties are officially classified, generally based on foliage maturity, into the following earliness classes: very early, early, mid-early, mid-late and late. In this paper early group includes also very early class and medium group embraces mid-early or mid-late classes. Number

2 of tested cultivars in each group changed from year to year between 2 and 35 as is shown in table 1. Every year a very similar manner of cultivation was applied: organic fertilisation with manure (22t ha -1 ) and mineral N, P, K in the amount of 80, 35, 125 kg ha -1, respectively. Irrigation and chemical control of late blight were not used. Temperature was measured at the height of 2m in weather station (longitude: E, latitude: N, altitude: 105 meters above sea level) situated closely to experimental field. Daily air temperature was calculated as an arithmetic mean of four records registered at one and seven o`clock in the morning and in the afternoon. Air temperature sum (TSUM) was calculated by adding the mean daily air temperature (diminished each by 2 O C) in the course of growing period, that is from emergence till the death of foliage. The values of TSUM calculated in the same way, with threshold of 2 O C, are used for potato crop growth simulation by means of model WOFOST for the following countries: Belgium, Denmark, France, Germany, Ireland, Luxemburg and United Kingdom (Boons-Prins et all, 1993; Guiking-Lens and Diepen, 1993). Results of Lv and TSUM listed in table 1 are average values for the number of cultivars tested in particular group and year. Statistic analysis was made by means of Statgraphics Plus for Windows version 4. RESULTS AND DISCUSSION Duration of growth is one of the main determinants of the total dry matter produced by crops. The main effect of temperature is on the rate of plant development and indirectly the length of vegetation. The length of vegetation of different earliness groups of potato is listed in table 1. The average values of Lv (day) and TSUM ( O C day) for 26 tested years were following: early cultivars 97 and 1446, medium cultivars 110 and 1666, late cultivars 122 and It is worth to notice that Lv was less variable by about 2% compared with sum of temperature. These three sets of data (tab.1) were analyzed with the Statgraphics 4.0 package using different regression models. Exponential model (y = e a+bx ) fitted in the best way the relationship between the Lv and the TSUM. The correlation coefficients indicate a moderately strong relationship between these parameters for early and medium group of potato crops (tab.3). These equations explain almost the half of the variation in the length of vegetation because values of r 2 equal about 45%. It is lower (17.7%) for late group of potato crops indicating a relatively weak relationship between tested variables. Results showed in this paper can be useful for working with simulation potato models, especially WOFOST. The plant data used in these models should often be modified in dependence on the region of cultivation and genetic traits of varieties. For example in file POT701 (Guiking-Lens and Diepen, 1993) value of TSUM equal 1700 O Cd (late cultivars) is applied for many European countries, among others Germany neighbouring country of Poland. It is lower by 76 O C day than

3 presented here for Central Poland (table 2). Equations presented here allow also to assess the potato length of historical vegetation based on daily air temperature. CONCLUDING REMARKS From this study can be concluded that air temperature influences significantly on duration of vegetative period of potato crops. The relation between these two variables could be described with an exponential regression accounting for almost 50% of the variance for early and medium varieties. REFERENCES [1] Boons-Prins E.R., Koning de G.H.J., Diepen C.A.van and Penning de Vries, Crop specific simulation parameters for yield forecasting across the European Community. Simulation Reports CABO-TT, no. 32, CABO-DLO Wageningen Agricultural University, 250 pp. [2] Ewing E.E.,Heyn W.D, Batutis E.J., Snyder R.G., Khedher M., Sandlan K.P. and Turner A.D., Modifications to the simulation model POTATO for use in New York. Agric. Systems, 33: [3] Guiking-Lens I.M. and Diepen C.A. van, A user guide for running WOFOST 6.0 on a personal computer. DLO-starting Centrum, Wageningen, 156pp. [4] Keulen H.van and Wolf J., Modelling of agricultural production: weather, soils and crops. Simulation monographs. Pudoc Wageningen, 479pp. [5] MacKerron D.K.L. and Waister P.D., A simple model of potato growth and yield. Part I. Model development and sensitivity analysis. Agric. For.Meteorol., 34: [6] Montheith J.L., Climatic variation and the growth of crops. Quart.J.R.Soc.,107: [7] Ng E. And Loomis R.S., Simulation of growth and yield of the potato. Simulation Monographs. Pudoc, Wageningen 147pp. [8] Squire G.R., Linkage between plant and weather in models of crop production. In: Kabat P. et all (editors), Modelling and parametrization of the soil-plant-atmosphere system. Wageningen Pers, Wageningen,

4 Table 1 Average values of length of vegetation (Lv) and air temperature sum (TSUM) for given number of varieties cultivated in particular year at Experimental Station in Jadwisin, Poland. Year Cultivar Lv TSUM earliness number day C day 1974 early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late

5 year cultivar earliness number Lv TSUM 1989 early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late early medium late

6 Table 2 Summary statistics of data sets presented in table 1, n = 26. item length of vegetation, Lv; day cultivar earliness early medium late LSD 0,05 average value maximum minimum median variability coefficient (%) air temperature sum, TSUM; O C day average value maximum minimum median variability coefficient ( %) Table 3 Results of regression analysis quantifying the relationship between length of vegetation of potato crops (Lv) and air temperature sum (T), n = 26. Cultivar group Regression equation r 2 SE 1 Level of significance 2 early Lve = 60.8 e T ** medium Lvm = 64.4 e T ** late Lvl = 85,0 e T * 1 standard error of estimation 2 significant at the level 0.01 (**) or 0.05 (*)