Tuber Growth Rate Research Articles

Ionic balance and growth of potatoes as affected by N plus P fertilization

Potato plants were grown in the San Luis Valley of Colorado under irrigation with different N and P levels applied to the soil. Growth rate of stems, leaves and tubers was measured. At three different growth stages the concentration of total N and organic anions or organic salts was determined. The organic anions (C-A) were assumed to equal the difference between the milliequivalents of cations (Na+, K+, Ca++, Mg++) and the milliequivalents of inorganic anions (Cl−, NO3 −, H2PO4, SO4 =) in the tissues. Application of N and P fertilizers increased leaf, stem, and tuber growth rates and, consequently, yields. Unfertilized plants had a high level of organic anions. Fertilization increased organic N, NO3 − -N, and P but decreased K and (C-A) in leaves and stems, except for the last leaf sampling where (C-A) of the fertilized plants had increased to the level of (C-A) in unfertilized plants. Fertilization increased Ca and Mg concentrations in stems. Fertilization decreased concentration of total cations and increased P in tubers. The N and (C-A) levels in leaves and stems associated with optimum tuber yield varied linearly with time with the former decreasing and the latter increasing with time. The tuber (C-A) decreased with time.

Analysis of Potato Growth Under Differing P Regimes. II. Time by P‐status Interactions for Growth and Leaf Efficiency1

AbstractFew full‐season studies of potato (Solanum tuberosum L.) growth under mid‐latitude environments have been conducted. Furthermore, published reports about effects of nutrient status on leaf efficiency in any species are inconclusive. Hence, the effects of factorially combined levels of initial soil P (SP = 35, 66, and 110 kg/ha) and row‐applied fertilizer P (FP = 0, 28, and 56 kg/ha) on dry matter accumulation, leaf‐area generation, leaf efficiency, and partitioning of assimilates by potatoes were studied via growth‐analysis concepts. Tops and tubers of field‐grown ‘Pungo’ potatoes (40,000 plants/ha on Portsmouth fsl—Typic Umbraquult, fine‐loamy, mixed, thermic) were harvested weekly, and all parameters essential to a detailed growth analysis were derived.Growth curves for P‐adequate plants (Sp ⋝ 66, FP > 0) were typically sigmoidal with three post‐emergent ontogenetic phases: 1) pre‐tuber vegetative (emergence − 28 days); 2) tuber initiation and early bulking concurrent with rapid leaf growth (28 to 50 days); and 3) continued tuber growth during rapid leaf loss followed by death of haulms. Plants on the low‐P extreme (SP = 35, FP = 0) never entered the third phase; they produced in 80 days only 50% of the “normal” leaf canopy (LAI = 1.6 vs. 3.2 at optimal P) and lost none of it. Curves for plants with moderate P supplies lay between these extremes. Row‐applied P enhanced early growth; but it also hastened leaf senescence and, if initial soil P was low, shortened the duration of tuber bulking.Leaf growth rate was maximal with 0.35% P in foliar tissue. Tuber growth rate was a quadratic function of leaf area during most of the tuber bulking period, but the estimate of 3.4 as optimal LAI was tenuous because no treatment generated a LAI greater than 3.2. Tuber yield was linearly related to leaf‐area duration (LAD); doubling the LAD resulted in a 45% increase in yield.Phosphorus deficiency reduced mean net assimilation rate (NAR) during early growth, had no statistically measurable effect during mid‐season [NAR (35 to 63 days) = 7.76 gm−2 day−1], but markedly increased NAR during late growth stages. Instantaneous estimates of NAR derived from growth equations suggested that effects of low P on leaf efficiency were even more severe and longer‐lasting than indicated by NAR's. Initiation of tubers as an additional metabolic sink halted a downward trend in NAR, and partitioning of assimilates between tops and tubers during bulking depended on P supply and the manner of supplying it.

COMPARISON OF GROWTH AND TUBER DEVELOPMENT IN THREE POTATO CULTIVARS WITH DIVERSE CANOPY SIZE

The basis of differences in tuber and plant development in potato, due to differences in canopy size, was studied by measuring changes in plant dry weight and leaf area throughout the growing season. Differing canopy sizes were obtained by selecting three cultivars from the Canada Potato Breeding Program. These were F57048, Grand Falls, and F62008, which normally produce small, medium and large sized canopies respectively, with similar tuber yields. Differences in total and tuber dry weight through the season were slight compared to differences observed in leaf and stem growth. The branching capacity of the cultivars appeared to be the major determinant of canopy size. In these three cultivars, as canopy size increased, the initial tuber growth rate immediately following tuberization decreased. Thus, in the two smaller cultivars, the early tuber growth rate was more critical in determining final yield than was the case in the large-canopied cultivar, F62008. As expected, the net assimilation rate increased as canopy size decreased. The evidence indicated that the demands of the developing tubers exerted the greatest influence on the net assimilation rate.

Einfluß des Calcium‐Angebotes auf Wachstumsrate und Calcium‐Gehalt von Kartoffelknollen

Effect of calcium supply on growth rate and calcium content of potato tubers..Using potato plants in water culture with a constant calcium supply to the roots, a study was made of the influence of additional supply of calcium to the tuber surface on growth rate and calcium content of the tubers.Under conditions of high relative humidity around the tubers the calcium nutrition of the tubers was exclusively dependent on the calcium supplied to the tuber surface („exogenous calcium”︁). With a high level of exogenous Ca the growth rate of the tubers was high and the rate of uptake of Ca was proportional to the tuber growth. With a low level of exogenous Ca the growth rate declined to a lower but constant value. In absence of exogenous supply of Ca the growth rate of the tubers declined gradually until growth ceased. Cessation of tuber growth occurred when the Ca content decreased below 0,36 mg Ca per g dry matter for smaller tubers and below 0,14 mg Ca per g dry matter for larger tubers.Severe Ca deficiency in potato tubers causes necrosis at the tuber apex.

Relationships of hollow heart in Irish potatoes to carbohydrate reabsorption and growth rate of tubers

Tubers of Irish Cobbler that were hollow grew faster than non-hollow tubers on the same plant. However, tubers of varieties without hollow heart grew just as rapidly as tubers of the variety with hollow heart. Therefore tuber growth rate was related to hollow heart occurring within a variety but could not account for differences between varieties. When plant foliage was pruned the C-14 label from sucrose was translocated from the tuber to the top of the plant. Our studies suggest hollow heart can occur in small tubers under the following conditions: (i) moisture stress in the tubers resulting in conversion of starch to sugar, followed by a rapid influx of water into the tuber resulting in rapid enlargement of the perimedullary zone and a separation in the pith that later develops into hollow heart, and/or (ii), following injury to some cells in the tuber due to reabsorption of minerals and carbohydrates or depletion of food reserves followed by tuber enlargement. It seems probable however that hollow heart that is initiated in large tubers is only associated with excessively rapid tuber enlargement without the involvement of reabsorption or depletion of food reserves.

Langstreckentransport von Calcium in Stolonen von Kartoffelpflanzen

Long‐distance transport of calcium in stolons in potato plantsIn potato plants grown in water culture the influence of the tuber growth rate and the Ca supply to the tubers as well as the effect of the relative humidity around the stolons and tubers on the 45Ca translocation in the stolon was investigated.If the stolon tip or the tuber were supplied with additional exogenous Ca and the relative humidity around the stolon or tuber was very high then 45Ca applied to the roots was translocated in a negligible amount into the stolon or tuber. Even when the supply of exogenous Ca to the tubers was low, the tubers exerted no “sink”‐effect on the 45Ca translocation within the stolon.Under conditions of high relative humidity around the stolon 45Ca applied to the stolon surface was nearly exclusively translocated in direction of the shoot. In contrast, under low relative humidity around the stolon or tuber 45Ca applied to the stolon surface or to the root system was translocated into the stolon tip and into the tuber.The results indicate that within the stolon Ca is exclusively translocated in the xylem. A “sink”‐effect of the tuber on the Ca translocation into the stolon as well as within the stolon was not been observed.