Luiz Torres de Miranda

Oito ciclos de seleção entre e dentro de famílias de meios irmãos no milho IAC-1

This paper presents the results of eight cycles of selection among and within half-sib families in the IAC-1 maize population. It was obtained an average progress of 1.9% per cycle in grain yield against an expected genetic progress of 8.8% per cycle. For ear index it was estimated an expected genetic progress of 1.5% per cycle if applied the same differential selection index as for yield. Nevertheless it was not done any systematic selection among progenies for this character. The percent of lodging did not alter greatly with the cycles of selection.

A análise foliar na nutrição do milho: I - Correlação entre analise de fôlhas e produção

A correlation between foliar analysis and yield of corn was established, based on 31 fertilizer experiments conducted during the period of 1962-64, at 16 different localities of the State of Sao Paulo. In these trials five levels each of N, P2O5 and K2O were used; plots with and without sulfur were also included. Arranging in groups all the trials showing positive coefficients of correlation for total nitrogen (24 trials) and phosphorus (26 trials), the following correlations for total nitrogen (24 trials) and phosphorus (26 trials), the following correlations were found in each case: nitrogen, r = 0.51**, y - 4.26 + 28.66 x; phosphorus, r = 0.47**, y = 43.21 + 160.83 x. As the K content of levaves was affected mainly by soil type, the correlations for leaf potassium were obtained separately special consideration being given to this circumstance. The nitrate content of midribs, required for best yields, varies in the same year from locality to locality and in the same site, from year to year. This uncontrollable variability, of course, makes the interpretation of nitrate data difficult. The plants not receiving sulfur averaged low yields and had lower sulfate--sulfur content in the leaves. [The normal ones had 40 kg S per hectare but all plots received a central dose of 60 kg per hectare of each N or P2O5, and 30kg per hectare of K2O] . It seems that the mean values for calcium and magnesium in leaves, obtained from the range of levels which provides high yields, may be indicative of normal composition. Limiting leaf nutrient values associated with 80 per cent maximum yields in the field are as follows: nitrogen (N), 2.90%; phosphorus (P), 0.230%; potassium (K) - latosolic B terra roxa type of soil, 1.70%; gravelly podzolized soils, 2.80%; other soil types, 2.10- 2.70%.

Métodos de analise dos danos da lagarta da espiga¹, em médias de gerações envolvendo IAC Maya e Zapalote Chico

The line Zapalote Chico 2451 (ZC 2451) resistant to the corn earworm, Heliothis zea, the commercial synthetic Brazilian variety IAC Maya XII, the F1 and F2 obtained with their cross, and the two back crosses between the F1 and both parents, were planted in the field in a randomized block with 10 replications. The earworm damage done to the ears was graded utilizing the revised scale described by WIDSTROM (27). The data obtained was analised by two different ways. The grades were distributed at first in two different classes: grades 0 and 1 and grades > 2. The grades were afterwards distributed in the following two classes: grades 0 and grades > 1. The chi-square test was applied to verify which of the two types of classes adjusts better with their respective expected ratios. The results showed that when the grades were divided in the classes 0+1 and > 2 the data were more uniform within each treatment. The analysis of variance for each damage class separately, presented F values highly significant for the classes zero and zero plus one, whereas for the classes > 1 and > 2 the damage averages were very similar and the F values were not significant. The class zero plus one had F value higher and the coefficient of variation smaller than the class zero. The ZC 2451 corn compared to the variety IAC Maya XII, exibited good resistance to the corn earworm, under the field conditions of Campinas, State of Sao Paulo, Brazil. This resistance is of the type non preference and or antibiosis, because there was a higher percentage of ears of ZC 2451 free of earworm damage.

Estimativas de parâmetros genéticos na população de milho IAC-1 opaco-2

Progeny tests used for the improvement of IAC-1 opaque-2 maize population led to estimates of a series of genetic parameters. Estimates obtained for variance among half-sib progenies, coefficient of genetic variance and aditive genetic variance permit to come to a conclusion that population will continue reacting favorably to selection. The estimates of expected progress in selection were quite proximate with the observed progress showing great efficiency in the methodology. Estimates of these genetic parameters of IAC-1 opaque-2 showed to be of great value in the study of selection in this population permiting reliable prediction of the genetic progress.

Adubação do milho XXVII: ensaios com diversos fosfatos (10.ª série)

Four trials comparing six phosphorus fertilizers for the production of corn (Zea mays L.) were conducted in 1962-63 at different localities of the State of Sao Paulo. Practically no effect of phosphorus was observed in one of the trials. As an average of the other three experiments and of the six phosphates tested the yield increases due to the doses of 60 and 120 kg/ha of total P2O5 corresponded to 13 and 18 per cent, respectively. The average increase due to ordinary superphosphate was 683 kg/ha of grain. Giving the value 100 to this increase, the relative efficiencies of the other phosphates were: thermophosphate, 127; mixture of 2/3 of ordinary superphosphate and 1/3 of Araxa phosphate, 75; Olinda phosphate, 71; Alvorada phosphate, 56; Araxa phosphate, 37. The last three carriers are local rock phosphates.

Cytological association between a knob on the short arm of chromosome 2 of maize and the latent-1 supergene

SUMMARYC-banding technique was applied in some maize materials with the purpose of verifing cytogenetical association between chromosome 2S knob and the presence and expression of latent-1 supergene and also mitotic chromosome characterization. Materials chosen were IP 48-5-3 Cateto Assis Brasil, its isoline IP 48-5-3-lte-1 carring latent-1 factor and Michoacan 21-1-104 latent-1 donnor. C-band number obtained was 3.26 ± 0.69 for IP 48-5-3 Assis Brasil, 7.86±1.57 for IP-48-5-3-lte-1 and 8.43 ±1.12 for Michoacan 21-1-104. The mean of total heterochromatin amount values obtained and expressed as percentage were 4.07±0.46; 9.68±1.59 and 13.99±2.05, respectively, C-band was used because of good correspondence between heterochromatic knobs and positive C-bands. IP 48-5-3 lte-1 isoline and Michoacan 21 showed positive C-band on short arm of chromosome 2 and IP 48-5-3 Assis Brasil did not show any band in the same chromosome.

Adubação do milho: XXIV - Resultados de um ensaio permanente com estêrco, calcário e NPK mineral

Neste trabalho sao apresentados os resultados dos nove primeiros anos de um ensaio de adubacao do milho instalado em terra-roxa-misturada da Estacao Experimental «Theodureto de Camargo», Campinas, no qual foram estudados, em esquema fatorial, tres niveis de esterco, tres de calcario e tres de NPK mineral. De esterco, usaram-se 0, 10 e 20 t/ha; de NPK, 0, 60-60-30 e 120-120-60 kg/ha de N-P2O5-K2O. Esses adubos foram empregados anualmente. O calcario so foi aplicado em dois anos: no primeiro, 2 e 4 t/ha; no terceiro, 2 e 0,85 t/ha. As producoes foram geralmente boas e, em media dos tratamentos, tenderam a crescer no decorrer do ensaio, o que se atribui a acumulacao de residuos das consecutivas adubacoes e ao uso de hibridos cada vez mais produtivos. Embora tendesse a melhorar um pouco nos ultimos anos, o efeito medio da calagem foi nulo, mas sua interacao com NPK foi significativa e positiva; respectivamente na ausencia e na presenca de NPK, as respostas ao corretivo corresponderam a -205 e +204 kg/ha. A reacao ao esterco foi linear e mais ou menos constante no decorrer do periodo estudado. A interacao com NPK foi significativa e negativa: tendo seu efeito medio alcancado +1.340 kg/ha na ausencia de NPK, na presenca desta adubacao baixou para apenas +443 kg/ha. No conjunto do periodo relatado, o efeito de NPK foi altamente significativo. Conquanto do tipo parabolico, a curva das producoes ainda era ascendente quando se usou a dose 2. Do que se disse linhas atras, deduz-se que a presenca do calcario aumentou e a do esterco diminuiu o efeito de NPK. A resposta a NPK baixou de +1.904 kg/ha, na ausencia, para +1.007 kg/ha na presenca do esterco. Todavia, as producoes cresceram sempre que se aumentaram as doses totais de nutrientes. As medias citadas nao representam bem o efeito de NPK, pois sua interacao com anos, altamente significativa, mostrou que ele aumentou no decorrer do ensaio.

Macronutrient content in the fourth leaves of corn related with yield

), pertencentes as parcelas adubadas e as sem adubo, aos 60-65 dias de idade da. planta. Nas amostras devidamente preparadas foram determinados N, P, K, Ca e Mg. Dispondo dos dados de producao e dos teores dos macronu-trientes das folhas referentes a ambos os tratamentos, num delinea-mento blocos inteiramente ao acaso, verificou-se que os efeitos da adubacao foram significativos apenas na producao e nos teores de nitrogenio. Pelo quadro 1 nota-se que as producoes das parcelas sem adubo variaram de 1.140 a 8.469 kg e os teores de N, de 1,59 a 3,71%, observando-se uma estreita correlacao entre essas duas variaveis: r = 0,75**. Para o fosforo e potassio, os coeficientes de correlacao foram r = 0,47* e r = 0,51**, respectivamente. Gallo e col. (

Fertilizer experiments with corn XXVII: trials with various phosphorus sources (10th Series)

Four trials comparing six phosphorus fertilizers for the production of corn (Zea mays L.) were conducted in 1962-63 at different localities of the State of Sao Paulo. Practically no effect of phosphorus was observed in one of the trials. As an average of the other three experiments and of the six phosphates tested the yield increases due to the doses of 60 and 120 kg/ha of total P2O5 corresponded to 13 and 18 per cent, respectively. The average increase due to ordinary superphosphate was 683 kg/ha of grain. Giving the value 100 to this increase, the relative efficiencies of the other phosphates were: thermophosphate, 127; mixture of 2/3 of ordinary superphosphate and 1/3 of Araxa phosphate, 75; Olinda phosphate, 71; Alvorada phosphate, 56; Araxa phosphate, 37. The last three carriers are local rock phosphates.

Relação entre teores de nitrogênio e fósforo e pH do solo, e a resposta à adubação fosfatada em milho

The correlation between phosphorus, nitrogen and pH in the soil and the response to phosphate application was studied in 33 NPK fertilizer trials of the 33 factorial design. The calculated responses to phosphorus based on the results of soil analysis and the actual yield values had the correlation coefficients r = 0.642 and r = 0.602 for the two levels, 60 and 120 kg of P2O5 per hectore, respectively. When the experiments in soils with a pH below 4.9 were excluded, as well as a single experiment in a soil extremely low in N, the remaining 24 trails gave the correlation values r = 0.844 and r = 0,877 for the two phosphorus levels respectively. It is believed that the corn response to phosphate application can be reasonably predicted based on phosphorus and nitrogen content and pH of the soil. The results of soil analysis may thus serve as a basis for phosphate fertilizer recomendation in case of this crop.