The Effects of Different Manurial Treatments on The Yield and Mineral Composition of Red Beet

Red beet was grown in factorial manurial experiments at two sites: at Wellesbourne annually from 1954 to 1964 in a rotation of vegetable crops and at Efford in 1959 only.

At Wellesbourne applications of FYM (20 tons per acre per crop), together with NPK fertilizers, consistently gave much higher yields than mineral fertilizers alone, but the relative effect of FYM did not increase as the experiment proceeded.

In the presence of FYM, yields of red beet increased with increasing rates of application of Nitrochalk (up to 124 lb. N per acre), but applications of phosphate and potash fertilizers did not affect yields.

In the absence of FYM, phosphate fertilizers did not increase yields significantly after 1959; there was an important interaction between the effects of the applications of Nitrochalk and SUlphate of potash. Each fertilizer applied alone produced small increases in yield, but when they were applied together at the highest rates used (186 lb. Nand 192 lb. K₂O per acre) large increases in yield were obtained and there was some indication that an even higher rate of application would have given a further increase in yield. At Efford, nitrogenous fertilizers increased yields significantly.

Applications of FYM increased the potassium and decreased the calcium and magnesium contents of red beet leaves and had only small effects on the nitrogen and phosphorus contents; in the roots, only the potassium content was altered (increased) by the FYM applications.

In general, in the absenc~ of FYM only potash fertilizer applications had large, consistent and significant effects on the mineral composition of the leaves and roots. At both sites, applications of sulphate of potash increased the potassium content of the leaves and had a much smaller depressing effect on the calcium and magnesium contents of the leaves but not, in general, of the roots.

The effects of the nitrogenous fertilizers on the total nitrogen content of the roots were relatively small, but could be important in relation to the processing quality of the beet.

The marked differences between the responses of red beet and early potatoes to the manurial treatments are discussed in relation to the nutrient contents of the plants.     

An Approach to the Study of Yearly and other Variation in Crop Yields

The effects of deep ploughing, shallow ploughing-with-subsoiling, shallow ploughing, and shallow rotary cultivation combined factorially with three manurial treatments on the yields of vegetable crops are described. Each of the five crops in the rotation was grown in each year from i960 to 1962 on a sandy loam at Wellesbourne.

Where a high level of fertility bad been built up by the use of farmyard manure (FYM), yields were subsequently maintained at a high level for a three-year period by the use of NPK fertilizers alone.

Plots which had received either FYM with NPK fertilizers for each crop from 1954 to 1962 (FYM -j- NPK), or FYM with NPK fertilizers from 1954 to 1959 but with NPK only from i960 to 1962 (residual FYM + NPK), gave much higher yields than plots which had received only nitrogenous fertilizers from 1954 to 1959 and NPK fertilizers from 1960 to 1962. The increases in yields from FYM + NPK over those from residual FYM + NPK were small, and significant only for autumn lettuce and leeks.

Although, on average, the differences between the yields from the three ploughing treatments were small (the largest was 10%) some of the differences were significant.

The ploughing treatments gave significantly higher yields of early peas, autumn lettuce, leeks and Brussels sprouts than shallow rotary cultivation ; with early summer cauliflowers, however, only shallow ploughing-with- subsoiling gave a higher yield than shallow rotary cultivation.     

The Effects of Different Manurial Treatments on The Yield and Mineral Composition of Early Potatoes

The effects of different manurial treatments on the yield and mineral composition of early potatoes are described. The crops were grown annually from 1954 to 1964 in a rotation of vegetable crops in a factorial manurial experiment on a sandy loam at Wellesbourne and, in i960 only, on a very fine sandy loam at Efford.

At Wellesbourne, farmyard manure (20 tons per acre per crop) with fertilizers consistently produced much higher yields than mineral fertilizers alone, and the relative effect of FYM increased from 1954 to 1959 but not subsequently. In years when moisture supplies were adequate, the larger part of the increase in yield could be attributed to effects of FYM on the early growth of the plants, and a smaller part to the increased rate of bulking of the tubers on the FYM plots. In dry years, however, growth during the harvest period was much slower on the fertilizer plots than on the FYM plots and the additional relative increase in yield on the latter during this period caused the overall effect of FYM to be larger than in the wetter years.

In the absence of FYM, each of the major nutrients N, P and K gave significant yield increases, but the need for adequate applications of phosphate and potash fertilizers together was emphasized by a marked interaction between their effects on yield. Applications of phosphate fertilizers had a particularly important effect early in the bulking period, whereas the effects of the nitrogenous fertilizers were greater at the later stages. In the presence of FYM, the fertilizer applications had significant effects only at the later stages of bulking, but at this time the amounts needed to give maximum yields were similar to those needed in the absence of FYM (124 lb. N, 36 lb. P₂O₅ 144 lb. K₂O (estimated), each per acre).

At Efford, applications of up to 4 cwt. per acre of sulphate of ammonia and 2 cwt. per acre of superphosphate (18% P₂2O₅) gave significant increases in yield, and higher rates would probably have given still higher yields. Potash fertilizers did not affect yields although they markedly increased the potash contents of the plants. The differences between the responses at the two sites are discussed in relation to soil conditions.

The leaves of plants manured with FYM (Wellesbourne) contained much more potassium and slightly more phosphorus than leaves from unmanured plants and, while the differences in potassium content were larger towards the end of the bulking period than at the beginning, the reverse was true of the phosphorus contents. Thus, to use leaf composition data to indicate possible shortages of nutrients in the soil, the samples of leaves for chemical analysis must be taken at several different times during the growth of the crop. The value, if any, of extra nutrients for FYM-manured plants cannot at present be assessed.

At Efford, applications of sulphate of potash increased the potassium content of the leaves to levels approaching those found in the manured plants at Wellesbourne and higher than those in the unmanured plants. Because of marked interactions between the effects of the phosphate and potash fertilizers at Wellesbourne and indications that phosphate applications at Efford may have been too low to ensure maximum yields, it does not seem possible to combine the data from the two experiments in order to suggest levels of the major nutrients in the potato leaves, at any particular stage or stages, which may be considered adequate for maximal yield production.

At Wellesbourne the standard error per plot was smaller for the manured series (8·1%) than for the unmanured (12·9%), indicating that growth was more uniform on the former.     

The Effect of Different Irrigation Treatments on the Growth and Yield of Early Summer Cauliflowers

Lettuce were grown during the winter of 1957–58 on the plots of a long-term manurial experiment in which the treatments had been applied to each crop from 1954 to 1957. Three rates of each of the three nutrients N, P and K were applied either with or without farmyard manure (20 tons per acre per crop) in a 3³ × 2 factorial design.

The mean yield from the plots which received farmyard manure (FYM) together with fertilizers was more than twice that from the plots which received fertilizers alone; the extra yield came from the greater number of lettuces that reached marketable condition on the former plots and not from an increase in the size of the plants. The date by which 50% of the plants that eventually reached marketable condition had been cut was almost 8 days earlier for the FYM plots than for the no-FYM plots. The different rates and combinations of fertilizers, when applied with FYM, did not produce different yield effects.

In the absence of FYM, applications of sulphate of potash and superphosphate each increased yields significantly (P =.0·05); applications of Nitrochalk, however, reduced yields but the reduction just failed to reach significance (P = 0·05). The treatments did not affect the 50% cutting date.

Where FYM had been applied, the fertilizer applications did not have differential effects on the mineral composition of the lettuce plants but, on average, there was twice as much potassium in the dry matter of plants (7·8%) as in plants from the no-FYM plus fertilizer plots (3·9%). In the absence of FYM, the fertilizer applications had marked differential effects on the mineral composition of the plants and these effects are discussed in relation to yield.     

The Effects of Different Primary Cultivations and Manurial Treatments on the Yield of Early Peas,Spring Cabbage,Leeks and Brussels Sprouts

The effects of different primary cultivations and manurial treatments on the yields of early peas, spring cabbage, leeks and Brussels sprouts grown in rotation on a sandy loam soil are described. The cultivation treatments consisted of deep ploughing, shallow ploughing-with-subsoiling, shallow ploughing, and shallow rotary cultivation, and these were combined fac- torially with three manurial treatments. Each of the crops in the rotation was grown in each year from 1954 to 1959. Special attention was paid to weed control and the experimental area was kept essentially free from weeds.

On average, the differences between the yields from the three ploughing treatments were small but, although the largest mean difference was only about 7%, several of the differences were significant.

The ploughing treatments gave significantly higher yields of all four crops than did shallow rotary cultivation ; the mean difference varied from 11% for peas and Brussels sprouts to almost 40% for spring cabbage.

Farmyard manure (FYM) with NPK fertilizers gave substantially higher yields of leeks/ spring cabbage and Brussels sprouts than nitrogenous fertilizer alone, but a smaller increase of only 18% in the yield of peas.

The following significant interactions are discussed : cultivations X years, manurial treatments X years, cultivations X manurial treatments and, for leeks only, cultivations X manurial treatments X years. It is concluded that the effects of some of the experimental treatments on the water available to the plant roots were, at least in part, responsible for some of the significant differences and interactions.

Certain aspects of experimental technique are also discussed.     

A Note on the Growth-Regulating Activity of 2:6-Dichlorophenoxyacetic Acid

During each of the four years 1957-60 the growth of the carrot crops in a long-term manurial experiment was studied. Significant increases in the yield of roots were produced by the application of farmyard manure and of potassic fertilizer but not by the application of nitrogenous or phosphatic fertilizers. The mean annual yields, and the responses to the applications of FYM and K, varied considerably from year to year.

The applications of FYM resulted in increases of 15-20% in the net assimilation rates and relative growth rates of the plants but these increases persisted for only 4-7 weeks when growth of the leaves on all plots was exponential. Subsequently net assimilation and relative growth rates of the plants on the FYM plots were slightly less than those on the no-FYM plots. It appeared that the initial differences in net assimilation rates were the main cause of the increased leafiness of the plants on the FYM plots, and hence of the increases in yields of roots.

Year-to-year differences in the total weight of leaves produced were related mainly to differences in the amount of rainfall during their growth. Yearly variation in root yields, however, was related both to the amount and to the distribution of the rainfall during growth.

The relative importance of variations in net assimilation rate and in leaf weight ratio are discussed.     

Rubus Stunt: A Virus Disease

In 1958, at three sites in the Vale of Evesham, a progressive increase in the yield of spring cabbage was obtained from increasing rates of application of nitrogenous fertilizers up to 279 lb. N per acre, as Nitrochalk. At a fourth, with later application of fertilizers and a relatively early cutting date, 6 cwt. per acre gave a yield response rather greater than at the other three sites, but higher rates of application of Nitrochalk produced no further increases in yield.

No yield advantage was gained by applying the fertilizer dressing in three doses during the growth of the crop rather than in one dose in the very early spring.

The uptake of potassium, phosphorus, magnesium and calcium by the plants increased as the rate of nitrogenous fertilizer increased. The need to maintain an adequate level of available potassium in the soil when using heavy dressings of nitrogenous fertilizers is emphasized.

The effect of a ploughed-in ley on the recovery of added nitrogen is discussed.     

The Effects of Manurial Treatments on The Yield and Quality of Carrot Seed

Seed crops of carrots were grown in 1962, 1963 and 1964, on plots of a 2⁴ N, P, K and farmyard manure factorial experiment. Significant seed yield responses were obtained to each of the fertilizers and to manure, as compared with the yields from the control plot with no manure or fertilizers.

Except when a seed-borne disease caused by Stemphylium radicinum was present, the germination of the ungraded seed was well above the statutory declarable minimum of 60% and there were no significant differences in germination caused by the manurial treatments.

The seed produced in 1963 and 1964 was of similar mean chemical composition to commercial seed and, although its composition was affected by the nitrogen and farmyard manure dressings, these variations in composition did not affect the yield of roots obtained from field sowings of the 1963 seed. The 1962 seed was exceptional in having a lower mean phosphorus concentration than commercial seed. The seed with the lowest phosphorus concentration was obtained from the plots which had received nitrogen but not phosphorus fertilizers, and the root yields from such seed were significantly lower than those from the seed containing higher concentrations of phosphorus.     

The Relation Between the Rate of Respiration of an Apple Fruit and its Content of Protein: I. The Value of this Relation Immediately After Picking

Tomato plants of two varieties (Potentate and Immuna) were grown for four seasons with different combinations of magnesium and potassium sulphate in heated glasshouses. Magnesium sulphate was applied either to the soil or as a foliar spray, with untreated plots as controls ; these treatments were combined factorially with two levels of soil potassium. The effects of the treatments on the magnesium and potassium contents of the soil, as extracted by 0 5N-acetic acid, are recorded.

Chlorosis of the leaves was widespread where magnesium was not applied. Foliar spraying effectively controlled the deficiency symptoms; treatment of the soil with magnesium sulphate was only partially successful in the first season but increasingly satisfactory thereafter.

In only one of the four seasons was there a significant increase in yield J due to the correction of magnesium deficiency. In that year (1959) the yields at the higher level of potassium were increased by 15%and 12%by the soil and spray treatments respectively (P=0·001).

The magnesium treatments slightly improved fruit quality as assessed by visual grading, mainly at the very low level of potassium in the last two seasons. The dominant factor affecting fruit quality was potassium, however, which markedly increased the proportion of uniformly coloured fruit and reduced the incidence of ripening disorders.

It is suggested that magnesium deficiency should be controlled by supplying this nutrient rather than by reducing the application of potassium salts below the quantity necessary for high fruit quality.

Variety Immuna gave higher yields and better quality fruit than Potentate throughout the trial.     

油菜素内酯对菜豆落花落荚作用的研究

以皇嘉牌油菜素内酯、防落素对菜豆进行处理,探索它们对花荚脱落作用的影响.结果表明:150 mg/kg HJNBR和35 mg/kg PCPA均能对菜豆前期花荚脱落有明显的抑制作用,且150 mg/kg HJNBR更能显著提高菜豆的总产量,但其对豆荚的生长速度并无显著的促进作用,对单荚重也无明显影响.即使用皇嘉牌油菜素内酯(HJNBR)使菜豆产量增加的原因主要是由于增加了菜豆的座荚率.     

The Micronutrient Content of Young Vegetable Plants as Affected by Farmyard Manure

Concentrations of copper, zinc, iron and manganese found in the laminae of five species of vegetable plants grown in a field experiment with added FYM or potash fertilizers are reported.

Manganese concentrations were depressed by FYM additions and this was associated with increased soil pH. Generally, the other micronutrient concentrations were little affected by the presence or absence of FYM, and no differences were detected which could be attributed to the effects of potassium nitrate as against potassium sulphate, although plant growth was stimulated markedly on the plots receiving FYM.

It is concluded that the effects of FYM on growth and yield are unlikely to be the result of increased availability of the micronutrients measured.     

A Factorial Nutritional Study of the Perpetual-Flowering Carnation Grown Under Glass

Two varieties of glasshouse carnations (Improved William Sim and Saugus White) have been grown under 48 different combinations of manurial treatment. The treatments consisted of three levels of nitrogen and two of potash in factorial combination, applied in solution through trickle irrigation equipment to beds of compost (steamed loam with 20% peat and 10% grit) containing two levels each of phosphate, magnesium sulphate and lime (carbonate).

Soil samples were taken periodically for the determination of nitrate, available phosphate and potash, pH and pC. The distribution of nutrients was also studied in irrigated and non-irrigated areas of the beds.

A tip-burn of the leaves of variety Saugus White, attributed tomanganese toxicity from the steamed loam, developed shortly after the plants became established in the beds. Symptoms of nitrogen and potassium deficiencies were observed in the second half of the trial.

The total numbers of blooms of both varieties were increased by 6-9% at the intermediate and high levels of nitrogen as compared with the lowest level of this nutrient (P=0.001). The higher level of phosphate increased the flowering of Improved William Sim by 20%, but was not beneficial to Saugus White. The higher level of potash increased the flowering of Saugus White but somewhat depressed that of Improved William Sim. The main effects of magnesium and lime were not significant, but both factors occurred in significant interactions. Averaged over all combinations of treatments, Saugus White yielded 24% more blooms than Improved William Sim.

Splitting of the calyx was markedly decreased at the higher levels of nitrogen (P=0.001), and increased to a lesser extent by the higher levels of phosphate (P=0.05), potash (P=0.001) and lime (p=0.05). Improved William Sim gave far more split calyces than Saugus White.

The weight of the aerial portions of the plants at the end of the trial was reduced by the higher levels of nitrogen and increased by the higher level of potash. The combination of high phosphate with low potash was particularly unfavourable to variety Saugus White. THE visual symptoms of acute mineral deficiencies of the carnation have been described by Messing (1958). Chan et al. (1958) reported factorial nutritional studies of the carnation (variety Apollo) in relation to nitrogen, phosphorus, potassium and calcium in culture solution. Flower production increased significantly with increasing nitrogen concentration, and also to a lesser extent with potassium concentration, but the effect of phosphorus was relatively small and not significant. Much of the available data relating to glasshouse carnations grown in soil is contained in bulletins and periodicals published for commercial growers in America. Without attempting a comprehensive survey of such data, one notes beneficial responses to nitrogen (Beach and Mussenbrock, 1948; Holley et al., 1951) and potash (Holley, 1953).

Despite the commercial importance of the carnation as a glasshouse crop, relatively little attention has been given to its nutritional requirements as grown in this country. A series of large-scale factorial nutritional studies was accordingly undertaken, the first of which is now reported.     

The Effects of Light Intensity,Day Temperature and Water Supply on the Fruit-Ripening Disorders and Yield of two Varieties of Tomato

A study was made of the effects on fruit-ripening disorders and crop yield of shaded and unshaded glasshouses maintained at both high and low daytime temperatures (80° F. (26 ? 5° C.) and 65° F. (18 ? 3° C.)), in which were grown two varieties of tomatoes (Potentate and Ware Cross) at two levels of watering.

Shading the glasshouses reduced the proportion of non-uniformly coloured fruit at the high temperature. At the low temperature, shading reduced the proportion in i960 but there was no effect in 1959. Light watering reduced the proportion of non-uniformly coloured fruit in the first year but it had little effect in the second year. The variety Ware Cross bore approximately 10% fewer non-uniformly coloured fruit than did Potentate in both years.

Shading the glasshouses reduced yield in both years, the decrease being greater (62%) in the very dull year of i960 than it was (40%) in the very sunny year of 1959. The house at the low day temperature yielded a 30% greater weight of crop than the warmer house. In both years the heavily watered plants yielded more than the lightly watered plants because of an increase in mean fruit size. Potentate and Ware Cross yielded similar weights of crop in both years but Ware Cross bore more fruits and had a smaller mean fruit size.

The gross cash return obtained in 1960 was reduced by shading the glasshouses, by maintaining a high day temperature and by growing the variety Potentate as opposed to Ware Cross. The differences in the watering regimes employed had little effect on the cash return obtained.

By assuming that yield and quality have simple mathematical relations with degree of shading, the profitability of shading is discussed. It is shown that shading is not likely to be profitable.     

草炭土生物复合肥料对菜心生长的影响

以菜心为试材,研究草炭土固定芽孢杆菌制成的生物复合肥对菜心生长的影响。结果表明:草炭土生物复合肥栽培中的菜心幼苗生长健壮,地上部分和地下部分的生长状况均优于其它处理,说明可将草炭土与生物有益菌进行固定化,形成优质的草炭土肥料应用于蔬菜育苗和生产中。     

The Response of Malling Jewel And Malling Exploit Raspberries to Different Soil Moisture Conditions and Straw Mulching

The raspberry varieties Mailing Jewel and Mailing Exploit were used to study growth and crop responses to mulching and irrigation from 1957 to 1962 inclusive.

Treatment A consisted of a wheat straw mulch applied deeply enough to form a complete surface cover; treatments B and C of water applications on unmulched cultivated soil at soil moisture tensions of 20 cm. and 50 cm. of mercury respectively, measured at 1 ft. depth. Treatment B was changed after i960 to a single 2-in. water application given when the raspberry fruits began to ripen. Plots under treatment D were cultivated, unwatered and unmulched.

Irrigation greatly increased the rate of cane growth but this was found to be a disadvantage in raspberries grown as continuous rows because the new cane tended to chafe and obscure ripe berries. Restricting irrigation to the pre-picking period reduced height growth but did not appear to reduce cane numbers or crop yield. Crop yield was increased by irrigation to about 30% more than was produced on the unwatered and unmulched plots, mainly as a result of increased berry size, but the full effect of irrigation on yield was not realized because cane numbers and height were restricted. Under the conditions of this experiment, in which the canes were thinned to a given density and tipped to a given height, a single 2-in. application of water at the commencement of ripening, i.e. when the berries showed the first tinge of pink, was a very economic irrigation treatment. Irrigation slightly delayed ripening, probably because of the harder tipping required by the irrigated canes.

The mulch conserved the equivalent of 2 in. of moisture and was intermediate in effect between the irrigation treatments B and C and treatment D in height growth, crop yield and berry size, but had a depressing effect on the production of new canes by the weaker-growing variety Mailing Jewel.     

PBO对菜豆产量效应的研究

以不同浓度的促控剂PBO,1001、50、2002、50倍液,对菜豆("美国供给者"品种)进行叶面喷施。结果表明:PBO能有效提高菜豆单荚重,对菜豆的产量有极显著地增加作用,尽管PBO也能增加菜豆结荚数,但对产量提高作用并不明显。在PBO各个浓度的处理中,以150倍液的PBO对单荚重增加的效应最为显著,比对照增加28.88%,为生产上适用的浓度,该试验的研究结果为菜豆施用PBO提高产量提供了理论依据。     

2种钙肥对菜心生长及品质的影响

采用73.0 mg/L的果蔬钙肥及1.25 g/L、2.5 g/L和3.75 g/L 3种浓度的氯化钙溶液对菜心进行叶面喷施,研究不同钙肥处理对菜心生长及品质的影响。试验结果表明,不同的钙肥处理均可促进菜心的生长发育,提高叶绿素含量、增加菜心的产量、改善菜心品质,但存在差异,73.0 mg/L的果蔬钙肥处理效果最好,低浓度氯化钙处理对菜心产量和品质影响很小,中浓度氯化钙处理影响比较大,高浓度氯化钙处理比中浓度处理效果差。在不同的生长发育期,作用效应有所不同,在菜心生长的初期各钙肥处理影响不大,生长中后期影响比较大。     

The Magnesium Content and Potassium Magnesium Ratio of Tomato Leaves in Relation to Degree of Chlorosis

The magnesium and potassium contents of the leaves of two tomato varieties have been studied for three seasons in a replicated nutritional trial in heated glasshouses. Magnesium sulphate was applied either to the soil or as a foliar spray, with untreated plots as controls, in combination with high and low levels of soil potassium.

The samples analysed consisted of upper (5th from the top) leaves in the first season, 5th and 15th leaves in the second, and lower (15th) leaves in the third; the lower leaves proved more responsive to added magnesium.

The treatments supplying magnesium increased the magnesium content of the foliage slightly in the first season and highly significantly in the subsequent years. Potassium had no effect on the magnesium content in the first season, but tended to depress it subsequently.

The degree of chlorosis, assessed visually, was closely related to the magnesium content of the lower leaves of both varieties. The relationship was approximately linear for values up to about 0· 4% Mg, above which little chlorosis was ever found; the correlation coefficient for values up to 0·5% Mg in the leaves was –0·94 (P=0·001). Severe chlorosis occurred below 0·25%–0·30% Mg.

The K{Mg ratios in the leaves were also significantly correlated (P=0· 001) with degree of chlorosis (r=+0·87 for values up to 0·5% Mg and +0·91 overall). Calculation of the multiple regression of chlorosis on % Mg and % K showed, however, that the regression coefficient of chlorosis on potassium content was not significant. The magnesium content of the lower leaves is thus regarded as a more satisfactory criterion of magnesium status than their K{Mg ratios.     

Virus,Fertilizer and Rootstock Effects on the Nutrition of Young Apple Trees

The chemical analyses of leaves of young apple trees on three clonal rootstocks with four different virus infections were compared. The trees were grown on plots that had received different N, P and K treatments for 40 years.

The viruses reduced leaf-N most in the one-year-old trees, and the effect was greater than that of 63 units per acre of fertilizer-N. Interactions occurred between virus and rootstocks; the leaf-N of trees on MM. 111 was reduced more by the viruses than that of trees on the other rootstocks. The omission of fertilizer-N had little effect on the leaf-N in one-year-old trees, but as they aged the effect became significant.

Fertilizer, virus and rootstock treatments all affected the levels of leaf-P. Virus effects were greatest on the leaf-P with rootstock MM. 104 and least with MM. 111, and leaf-P with MM. 104 was generally higher than that of trees on the other rootstocks. The omission of fertilizer-N increased leaf-P more than did the application of fertilizer-P.

Rootstock and fertilizer treatments affected the level of leaf-K throughout the experiment, but virus effects were significant only in the two-year-old trees.

Magnesium and calcium levels in the leaves were affected by fertilizer, root-stock and virus treatments. The presence of viruses usually reduced both magnesium and calcium, and trees on MM. 106 were generally higher in leaf-Mg and Ca than trees on the other rootstocks. The effects of the latent viruses on nutrition as indicated by leaf analysis were less than those shown on growth and flowering.     

Edge Effects in a Cocoa Shade and Manurial Experiment

The separate recording of “edges” and “cores” of the plots of a cocoa shade and manurial experiment has shown that the gross plot yield exceeds the guarded plot yield by about 17%. Previously published yields of this experiment have been based on unguarded plots and are presumably correspondingly in error, at least in recent years. (The edge effects may not have been so great in earlier years.)

At interfaces between manured and unmanured plots there was a substantial manurial edge effect, the edge rows of the unmanured plots apparently deriving almost as much benefit from the fertilizer as did the manured plots themselves.