THE RELATION OF SOIL TEST VALUES TO FERTILIZER RESPONSE BY THE POTATO: III. EXCHANGEABLE POTASSIUM AND POTASSIUM FERTILIZER REQUIREMENTS

1964 ◽  
Vol 44 (3) ◽  
pp. 310-318 ◽  
Author(s):  
D. C. MacKay ◽  
C. R. MacEachern ◽  
R. F. Bishop

In experiments conducted at 46 locations over a 6-year period soil potassium levels ranged from 46 to 361 p.p.m. in exchangeable potassium and from 1.1 to 9.6% K saturation. The average yield of tubers on zero-K plots was 86.2% of the maximum (yield obtained from optimum K fertilization) and the zero-K plots produced less than 75% of the maximum at only two locations.Utilization of Bray's modified Mitscherlich equations indicated high variability in c1 values and poor correlation of relative yields (as percentages of the maxima) with soil test values. Expressing soil K as % K saturation provided only slightly better correlations than exchangeable K.The polynomial response equation relating absolute yields (bu/acre) with rates of applied potassium was highly significant, and near maximum yields of tubers were obtained at 150 lb/acre of K. When soils were grouped according to exchangeable K values into "high" (> 230 p.p.m.), "medium" (230–130 p.p.m.), and "low" (< 130 p.p.m.) classes, similar responses to application of K fertilizers were obtained for each. However, greater yields of tubers resulted on the higher soil test classes throughout the entire range of treatments.A highly significant linear depression in dry matter content resulted from potassium applications, with each 50 lb/acre increment of K depressing dry matter by 0.5%.

HortScience ◽  
2008 ◽  
Vol 43 (5) ◽  
pp. 1611-1614 ◽  
Author(s):  
André Pereira ◽  
Nilson Villa Nova

There is currently a great deal of interest in estimating crop productivity as a function of climatic factors by means of different crop weather models. In this article, an agrometeorological model based on maximum carbon dioxide assimilation rates for C3 plants, fraction of photosynthetically active radiation, air temperature, photoperiod duration, and crop parameters is assessed as to its performance under tropical conditions. Crop parameters include leaf area, harvest index, dry matter content of potato tubers, and crop cycles to estimate potential potato yields. Productivity obtained with the cultivar Itararé, grown with adequate soil water supply conditions at four different sites in the state of São Paulo (Itararé, Piracicaba, Tatuí, and São Manuel), Brazil, was used to test the model. The results revealed excellent performance of the agrometeorological model proposed here with an underestimation of irrigated potato productivity of less than 10%.


1995 ◽  
Vol 35 (6) ◽  
pp. 739 ◽  
Author(s):  
EJ Havilah ◽  
AG Kaiser ◽  
H Nicol

A scoring system based on the position of the boundary (milkline) between the solid starch phase and the liquid phase on the surface of the maize kernel was evaluated as an indicator of crop stage of maturity. Milkline score (MLS) varies from 0 when the kernel contents are all liquid and no milkline is visible to 5 when the kernel contents are all solid and grain filling is complete. The scoring sytem is continuous in intervals of 0.5 units. The MLS was linearly related to the dry matter (DM) content of the cro in experiments at Nowra (R2 = 0.72), Wagga Wagga (R2= 0.82), and Grafton (R2 = 0.65). The predicted dry matter content at MLS 2.5 was 34.2% at Nowra, 36.0% at Wagga Wagga, and 33.7% at Grafton. Under normal seasonal conditions, milkline scoring can be used by farmers to help decide when their crops are ready for harvest. Crop DM is optimal for silage productions when MLS is in the range 2-3. However, the technique may not be reliable with severely stressed crops. Sampling 10 cobs from an area of 0.25 ha gave a 95% confidence of detecting the MLS with a precision � 0.37 unit. At Nowra the milkline moved down the kernel at a rate of 1 MLS unit/9 days. This rate may be different in other environments. At the same site there was a significant (P<0.05) quadratic relationship between milkline score and DM yield, with maximum yield obtained at MLS 3.4. However, this relationship accounted for only 16.76% of the variation, and clearly, other factors influenced DM yield.


2009 ◽  
Vol 57 (2) ◽  
pp. 119-125
Author(s):  
G. Hadi

The dry matter and moisture contents of the aboveground vegetative organs and kernels of four maize hybrids were studied in Martonvásár at five harvest dates, with four replications per hybrid. The dry matter yield per hectare of the kernels and other plant organs were investigated in order to obtain data on the optimum date of harvest for the purposes of biogas and silage production.It was found that the dry mass of the aboveground vegetative organs, both individually and in total, did not increase after silking. During the last third of the ripening period, however, a significant reduction in the dry matter content was sometimes observed as a function of the length of the vegetation period. The data suggest that, with the exception of extreme weather conditions or an extremely long vegetation period, the maximum dry matter yield could be expected to range from 22–42%, depending on the vegetation period of the variety. The harvest date should be chosen to give a kernel moisture content of above 35% for biogas production and below 35% for silage production. In this phenophase most varieties mature when the stalks are still green, so it is unlikely that transport costs can be reduced by waiting for the vegetative mass to dry.


2020 ◽  
pp. 16-19
Author(s):  
Е.В. Янченко

Цель исследований – дать оценку сохраняемости и болезнеустойчивости современных сортов и гибридов моркови столовой и определить корреляционные зависимости влияния биохимических показателей качества на сохраняемость и степень поражения моркови столовой различными видами болезней в процессе хранения. Исследования проводились в 2011–2016 годах во ВНИИО – филиале ФГБНУ ФНЦО по общепринятым методикам. В биохимической лаборатории отдела земледелия и агрохимии содержание сухого вещества определяли высушиванием до абсолютно сухого веса, общего сахара – по Бертрану, аскорбиновой кислоты – по Мурри, нитраты – ионоселективным методом. При характеристике моркови столовой важнейший показатель, определяющий его качество – количество сухого вещества и сахаров. В процессе хранения были выявлены следующие болезни моркови: серая гниль (Botrytis cinerea Pers. ex Fr.), белая гниль (Sclerotinia sclerotiorum (Lib.)), белая парша (Rhizoctonia carotae Rad.), альтернариоз (Alternaria radicina M., Dr. et E.). В большей степени сортообразцы моркови столовой поражались серой гнилью. Лучшими по сохраняемости сортообразцами были Корсар (94,6%), F1Берлин (94,5%), Берликум Роял (94,1%) и F1 Звезда (94%). Сохраняемость у зарубежных сортов и гибридов моркови столовой была немного выше, чем у отечественных (на 0,4%) как за счет меньшей величины убыли массы (6,3% против 6,4%), так и потерь от болезней (1,6% против 1,9%). Сохраняемость корнеплодов моркови находится в прямой корреляционной зависимости от содержания сухого вещества (r=+0,41), каротиноидов (r=+0,39), моносахаров (r­=+0,30) и суммы сахаров (r=+0,27). Проявление серой гнили находится в обратной корреляционной связи с содержанием сухого вещества и каротиноидов (r=-0,37 и r=-0,35 соответственно), белой парши – в прямой корреляции с содержанием сухого вещества , моносахаров и дисахаров (r= +0,21; r= +0,39; r= -0,41 соответственно), белой гнили в обратной корреляционной связи с содержанием сухого вещества, моносахаров и дисахаров. The purpose of the research is to assess the persistence and disease resistance of modern varieties and hybrids of carrots and to determine the correlation between the influence of biochemical quality indicators on the persistence and degree of damage to carrots by various types of diseases during storage. The research was conducted in 2011–2016 at ARRIVG – branch of FSBSI FSVC, according to generally accepted methods. In the biochemical laboratory of the Department of Agriculture and Agrochemistry, the dry matter content was determined by drying to absolutely dry weight, total sugar – by Bertran, ascorbic acid – by Murri, nitrates – by the ion-selective method. When describing carrots, the most important indicator that determines its quality is the amount of dry matter and sugars. During storage, the following diseases of carrots were detected: gray rot (Botrytis cinerea Pers. ex Fr.), white rot (Sclerotinia sclerotiorum (Lib.), white scab (Rhizoctonia carotae Rad.), alternariasis (Alternaria radicina M., Dr. et E.). To a greater extent, varieties of table carrots were affected by gray rot. The best preserved varieties were Corsar (94.6%), F1 Berlin (94.5%), Berlicum Royal (94.1%) and F1 Zvezda (94%). The persistence of foreign varieties and hybrids of table carrots was slightly higher than that of domestic ones by 0.4%. both due to a smaller amount of weight loss (6.3% vs. 6.4%) and losses from diseases (1.6% vs. 1.9%). The persistence of carrot root crops is directly correlated with the content of dry matter (r=+0.41), carotenoids (r=+0.39), monosaccharides (r=+0.30) and the amount of sugars (r=+0.27). The manifestation of gray rot is in inverse correlation with the content of dry matter and carotenoids (r=-0.37 and r=-0.35, respectively), white scab is in direct correlation with the content of dry matter (r= +0.21; r= +0.39; r= –0.41, respectively), white rot is in inverse correlation with the content of dry matter, monosaccharides and disaccharides.


2017 ◽  
Vol 43 (8) ◽  
pp. 1234
Author(s):  
Dao-Bin TANG ◽  
Jian-Gang AN ◽  
Yi DING ◽  
Hui BAI ◽  
Kai ZHANG ◽  
...  

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