Brazil's coffee farmers balk at investing in crops even as prices rally

Reuters - Reese Ewing  -  SAO PAULO  Thu Aug 28, 2014 3:24pm EDT

Three years ago, a record surge in arabica prices spurred a wave of investment across coffee plantations in top grower Brazil, as farmers scrambled to fill a supply gap left by Central America after heavy rains damaged crops.

The following year, in 2012, Brazil's output rose by 19 percent, hitting a record 38 million bags.

But a surge in prices this year is not having a similar effect. While benchmark bean prices have rallied more than 90 percent from the seven-year lows hit last November, they remain at least 20 percent below where farmers say would consider plowing more money into fertilizer or expanding acreage.

A Reuters survey of nine cooperatives and producers in Minas Gerais, Sao Paulo and Parana states found that farmers in Brazil's southeast, the region worst hit by a drought that ranks as the worst in five decades and which has caused the run-up in prices, have no plans to invest more than usual this year to boost output.

The drought, which peaked in the crucial January through March period and robbed farmers of as much as 30 percent of their crop, has weakened appetite to invest, especially with the debts that farmers already are carrying after painfully low prices in 2013.

"You're not going to see a lot of enthusiasm to invest after the drought. There are 30 types of businesses with better returns than coffee right now," producer Luis Hafers said. "For now, my investments are on hold."

Without investment in crop nutrients over the next few months, it could take years for the country's coffee trees to recover, potentially hurting global supplies of arabica.

The official estimate from the Agriculture Ministry in May put Brazil's arabica harvest, which was ravaged by the drought, at 32 million bags, down 16 percent from last year. Many fear output in 2015 may be even lower.

ROILED BY ROYA, BULKING AT FERTILIZER

A devastating leaf rust in Central American and war and logistical challenges in Africa will make it harder for other producers of quality arabicas to fill the vacuum that will be left by Brazil in the coming years.

"We're getting 400 reais a bag ($1.33/lb) for good cup arabica, but we need to see 500 reais to consider planting more or additional fertilizer," said Walter Dutra, co-owner of a 300-hectare farm in Minas Gerais, Brazil's main coffee state.

Most of the representatives of Brazil's coffee industry who spoke with Reuters said they need to see prices to rise by a quarter before they would consider new investment.

Futures prices for arabicas have rallied almost 30 percent since mid-July, hitting $2.00 per lb this week, but they are still 8 percent from April highs of $2.15/lb and down more than a third from 2011 highs above $3.

"Producers are making money finally, but not enough," Anderson Oliveira de Souza, manager at the Cocatrel cooperative said. In 2011/12, Cocatrel sold 40,000 tonnes of fertilizer to coffee producers on the farms in the Tres Pontas area of Minas Gerais, but in the last two years it sold only 26,000 tonnes.

"We'll be lucky to sell that this year because producers' debts are restricting their access to credit," Souza said.

Application of nitrogen, phosphorus and potassium will start in September and continue through April, but the effects will not be seen until the 2016 harvest.

Over the first half of 2014, fertilizer sales to the coffee sector have been up 1.2 percent, according to Brazil's largest coffee cooperative, Cooxupe, in southern Minas Gerais, the state that produces half the country's coffee.

"After selling coffee at below cost in 2013, we lacked capital, so we cut back on fertilizer," said Marco Antonio Jacob, producer in Sao Paulo state.

"Now, the drought took 30 to 40 percent of our crop, so again, where are we supposed to get this money to invest?"

Coffee Weather Woes Spread to Central America -- WSJ Blog

Leslie Josephs

Weather woes are mounting for coffee growers and coffee lovers.

  Drought has taken hold in Central America, adding to worries over a drop in global production that

has already driven up prices for consumers.

  The most-actively traded arabica-coffee futures contract rose above $2 a pound on Wednesday, as

coffee production in the region appeared poised for another drop.

  While Central America produces about 10% of the world's coffee, growers there are already battling

a fungus that has reduced output. Meanwhile, the world's top coffee grower, Brazil, was hit with its

own crop-damaging drought.

  "The cherries are not filling up because of the lack of rain," said Nils Leporowski, president of

the Guatemalan Coffee Association, known as Anacafe, following a visit to coffee farms in the

country. The Guatemalan government declared a state of emergency in 16 of the country's 22 provinces

earlier this week as a result of the drought.

  A lack of water stunts the development of coffee cherries, which contain the seeds that are

roasted and ground to make coffee beverages. Often following a drought, the cherries will appear

healthy, turning a deep red color, but contain no seeds.

  The next harvest starts in October, and moisture during the traditionally rainy months in Central

America is key to the crop's maturation process.

  Exports of arabica beans from Latin America, excluding Brazil, are down 3.2% since this season

began last year, according to Anacafe, with double-digit drops in Guatemala, El Salvador, Nicaragua

and Mexico.

  The dry weather could push prices even higher, analysts say. Guatemala "could be just like

Brazil," said Jack Scoville, a vice president at Chicago brokerage Price Futures Group, adding that

prices could reach $2.20 a pound in the coming weeks. "The potential for lower crops this year and

next are decent."

Arabica-coffee prices are up more than 80% this year, a rally ignited by Brazil's drought.

  Growers in Brazil, the source of one-third of the world's coffee supply, will harvest between 5%

and 10% less coffee this year, according to trade groups and exporters.

  That will likely tip the world into its first supply deficit in three years in the 2014-15 season,

which starts in October, according to the International Coffee Organization.

World Coffee Weather

Brazil Slightly Cooler, Restricted Rainfall Into Weekend

By Andy Karst

           Kansas City, August 27 (World Weather, Inc.) – Some cooling was noted in Parana and southernmost Sao Paulo, Brazil Tuesday and the cooler air will advance northward during the balance of this week. Very little rain of significance will accompany the cooling trend, but there will be some precipitation mostly near the coast. Espirito Santo, Rio de Janeiro, Zona de Mata and eastern Bahia will be most vulnerable to showers Friday and Saturday with today and Thursday’s precipitation a little further south. Most interior coffee areas will not be impacted by much meaningful rain. Showers will return in southern crop areas next week and they may be more significant in the middle and latter part of the week, but not likely great enough for flowering.  A tropical disturbance located east of the Greater Antilles will move across the Caribbean Sea during the next several days and should not have much of an impact on coffee in the Greater Antilles other than a brief increase in shower and thunderstorm activity.  Another round of rain occurred in the Central Highlands of Vietnam Tuesday and conditions for coffee should continue to improve as additional rain is expected during the next week.  Beneficial rain fell on nearly all of Ivory Coast and Ghana Tuesday.

BRAZIL

            Mostly dry weather occurred in Brazil coffee areas Tuesday. The only rain noted was at the port city of Sao Paulo where 2 millimeters and east-central Bahia resulted. High temperatures Tuesday were in the middle and upper 20s Celsius in Parana and southwestern Sao Paulo and in the upper 20s to lower 30s in most other areas. Extreme highs of 34 to 36 occurred from northern Minas Gerais to central Bahia.  Lows this morning were 10 to 17 most often with readings of 18 to 22 in some northern and eastern areas. 

            Today’s forecast has not changed much from that of Tuesday. Totally dry weather is not likely through the weekend, but the few showers that occur periodically are most likely near the Atlantic coast and will generate 1 to 8 millimeters of rain most often with an infrequent occurrence of amounts to 15 millimeters. Friday and Saturday may be wettest from Espirito Santo to eastern Bahia. Most interior coffee areas will not be impacted by meaningful rain prior to next week.

            A more unstable atmosphere may evolve in southern Brazil coffee areas next week. Showers will begin in Parana and coastal Sao Paulo Monday and increase September 2-6 while spreading northeast to Rio de Janeiro.  A few showers may reach into Zona de Mata and Espirito Santo. Most of the daily rainfall will continue light varying from 3 to 10 millimeters with a rare occurrence of 15-20 millimeters. Most of the advertised rainfall is not expected to be great enough to change crop or soil conditions, but there will be more showers during that period of time than during any day this week.

                        Some additional cooling is expected today into the coming weekend in southern coffee production areas. The cooling trend will lower daily high temperatures to the lower and middle 20s south while staying mostly in the middle and upper 20s to lower 30s in the north. Lowest morning temperatures will be in the range of 8 to 15 in the south and 10 to 18 with a few readings over 20 in the north. In contrast, today will generate many highs in the upper 20s through the middle 30s with extreme highs of 35-37 in northern Minas Gerais and central Bahia.

Arabica-Coffee Futures Climb Above $2/lb

Leslie Josephs

  NEW YORK--Arabica-coffee futures rose above $2 a pound Wednesday as dry weather from Brazil to

Guatemala fed concerns over the world's supply of coffee.

  Arabica for December delivery on the ICE Futures U.S. exchange was up 2.1% at $2.0150 a pound, the

highest since Aug. 1.

  On Tuesday, the government of Guatemala, Central America's second-largest coffee grower after

Honduras, declared a state of emergency because of extreme drought.

  It is the latest threat to coffee production, which was already hit this year by a severe drought

in top grower Brazil. Industry groups and exporters have lowered their estimates for output this

year, which has sent prices to two-year highs, prompting roasters such as Folgers maker J.M. Smucker

Co. and Starbucks Corp. to raise prices. Arabica-coffee futures are up 81% this year.

  Guatemala "could be just like Brazil," said Jack Scoville, a vice president at Chicago brokerage

Price Futures Group. "The potential for lower crops this year and next are decent."

  Brazil's weather continues to fuel worries over coffee supplies. Early rains there followed by

current dry weather could cause coffee trees to abort flowers that opened early, said Rodrigo Costa,

coffee director at brokerage Newedge.

  That process would prevent coffee cherries, which contain the seeds that are roasted and ground to

make coffee beverages, from developing.

  In other markets, raw sugar for October delivery was up 1.1% at 15.88 cents a pound, following an

estimate showing the world's sugar surplus slipping next year.

  Global sugar production is likely to outpace demand by 1.3 million metric tons by Sept. 30, 2015,

the London-based said Tuesday. While that would be the fifth consecutive surplus, it is about a

quarter of the surplus the ISO has forecast for the current year.

  November orange-juice concentrate was up 0.2% at $1.5195 a pound, while December cocoa was 0.5%

lower at $3,199 a ton. December cotton was 0.1% lower at 66.83 cents a pound.

Produção de café do Brasil terá maior queda desde 1965

A produção do Brasil, maior produtor do mundo, pode cair 18 por cento quando a colheita terminar no mês que vem

Bloomberg  

A seca prolongada no Brasil já custou metade da colheita do café de José Francisco Pereira. No ano que vem pode ser ainda pior e o país está a caminho da primeira queda de três anos na produção desde 1965.

"Todos estão rezando pela chuva", disse Pereira, diretor-geral da Monte Alegre Coffees, uma produtora dona de 2.500 hectares com sede em Alfenas, Minas Gerais, que previu uma colheita de 45.000 sacas nesta safra, abaixo das 82.000 da temporada passada.

A produção do Brasil, maior produtor do mundo, pode cair 18 por cento quando a colheita terminar no mês que vem, para 40,1 milhões de sacas, estima o Conselho Nacional do Café, após um declínio de 3,1 por cento no ano passado. Com a piora dos danos antes do início da primavera no Hemisfério Sul, o conselho disse que os agricultores poderão colher menos de 40 milhões de sacas em 2015, criando a queda mais longa em três décadas.

O Citigroup Inc. previu em 21 de agosto que o déficit global na produção pode durar até 2016 por causa da escassez no Brasil, que no ano passado respondeu por 36 por cento da oferta mundial.

Os contratos futuros, que se valorizaram mais que os de qualquer outra commodity neste ano, podem subir mais 19 por cento até o fim de dezembro, para US$ 2,25 a libra-peso (454 gramas), mostrou uma consulta da Bloomberg a 18 analistas. O incremento está forçando compradores como a J.M. Smucker Co., produtora da Folgers, a marca mais vendida dos EUA, a elevar os preços no varejo.

"O mercado está vulnerável ao incremento devido a todos os problemas no Brasil", disse ontem Donald Selkin, que ajuda a gerenciar US$ 3 bilhões como estrategista-chefe de mercado da National Securities Corp. em Nova York. "As pessoas estão prevendo ofertas mais apertadas e esperando evoluções climáticas mais drásticas".

Commodity sobe
O café arábica subiu 71 por cento neste ano, para US$ 1,892, na ICE Futures U.S., o maior ganho entre 22 matérias-primas no índice Bloomberg Commodity, que caiu 0,1 por cento. O índice de ações MSCI All-Country World subiu 5,4 por cento no mesmo período. O índice Bloomberg Treasury Bond teve um incremento de 4,1 por cento.

O Brasil está enfrentando sua pior seca em décadas. Os reservatórios das regiões Sudeste e Centro-Oeste, onde está a maioria das plantações de café do país, estavam em menos de 32 por cento de sua capacidade em 24 de agosto, contra a média de 59,3 por cento em agosto nos 13 anos anteriores, segundo a Operadora Nacional do Sistema Elétrico, a ONS. O Brasil gera cerca de 70 por cento de sua energia com usinas hidrelétricas.

Agravando os danos à colheita deste ano, em julho chuvas torrenciais inesperadas levaram ao florescimento prematuro de árvores cujos frutos já haviam sido colhidos. Quando o clima seco retornou neste mês, as flores murcharam e caíram, prejudicando ainda mais o rendimento potencial para 2015.

Demanda crescente
A colheita menor do Brasil e o consumo crescente redundarão em um déficit da produção global de até 10 milhões de sacas no ano que começa em 1º de outubro, disse a Organização Internacional do Café, em Londres, em 1º de agosto. A Volcafé Ltd., operadora de commodities da ED&F Man Holdings Ltd., estimou o déficit em 11,3 milhões de sacas. Cerca de 58 por cento da produção mundial é de café arábica, o grão preferido pela Starbucks, enquanto o restante é da variedade robusta, usada em café instantâneos e nos blends.

Muito do dano para a colheita da próxima safra pode já ter sido feito no Brasil.

"O crescimento foi muito lento", disse Alemar Braga Rena, pesquisador independente e professor de Agronomia aposentado da Universidade Federal de Viçosa, em Minas Gerais. "As raízes são o cérebro da planta e elas foram prejudicadas pelo calor e pela falta de água, o que as tornou incapazes de absorver nutrientes".

Arabica Coffee, Orange Juice, Sugar Rise on Supply Worries

Alexandra Wexler

  NEW YORK-Arabica-coffee prices surged to a more than three-month high on Tuesday as investors

worried about the harvest in top grower and exporter Brazil.

  The source of more than half of the world's arabica coffee experienced its worst drought in

decades this year, which has reduced the size of the current harvest and damaged trees.

  Weather in Brazil's arabica-growing regions has been less than favorable, WeatherBELL Analytics

said in a note. "Given the forecast over the next 30 days, there is an enhanced risk of flowers

aborting in the arabica areas," the meteorological consulting firm said.

  A weak flowering would mean a smaller amount of coffee beans would be produced during the 2015

season.

  Arabica coffee for delivery in December on the ICE Futures U.S. exchange ended 5.2% higher at

$1.9745 a pound, the highest level since May 7 and the biggest one-day gain since July 31.

  Brazil's National Coffee Council expects the 2014 and 2015 coffee harvests to produce about 40

million bags of coffee each. Its forecast for the current year is about 20% smaller than its

original estimate because of the drought. Each bag weighs 132 pounds.

  "If one is worried about supply tightness, it would make sense to get in," said Rodrigo Costa,

coffee director at brokerage Newedge in New York.

   Global coffee production could fall short of demand next season by the largest amount in almost a

decade due to smaller harvests in Brazil, the International Coffee Organization said last month.

  Orange-juice futures also jumped Tuesday as the churning of Hurricane Cristobal off the coast of

top orange-producing state Florida served as a reminder to investors that the Atlantic hurricane

season is far from over.

  "It's an awakening to the market," said Boyd Cruel, senior analyst at Vision Financial Markets in

Chicago.

  Orange juice for November delivery settled up 4.9% at $1.5160 a pound, the biggest one-day jump

since Nov. 8, 2013, and the highest close since July 23.

  The June-November Atlantic hurricane season could bring potentially damaging storms to Florida,

where the coming crop is already expected to be the smallest since the mid-1960s. Previous

hurricanes have damaged groves and ripped unripe fruit from the trees. Orange-juice prices usually

rise when a storm targets the state.

  Raw-sugar futures got a boost after Brazilian sugar-cane industry group Unica lowered its forecast

for the  center-south region's cane harvest to 545.9 million metric tons, down 5.9% from an earlier

estimate. Raw sugar for delivery in October ended up 2.3% at 15.71 cents a pound, the largest

one-day gain since June 20.

  However, sugar output in top producer Brazil's main growing region is still up 6.4% during the

season through the first half of August, and the global sugar market is likely to register a supply

surplus of 1.31 million metric tons for the season, according to the latest outlook from the

London-based International Sugar Organization. "Any possible price recovery brought by production

shocks over the course of 2014-15 might be muted by the huge stocks accumulated since the beginning

of the surplus phase in 2010-11," the ISO said.

  In other markets, December-delivery cotton ended up 1.1% at 66.89 cents a pound and cocoa for

December delivery ended down 0.1% at $3,216 a ton.

Brazil's Unica Cuts Center-South Sugarcane Crush Estimate Because of Drought

Jeffrey Lewis

  SAO PAULO--The worst drought in decades in Brazil's center-south region will cut the area's

sugarcane crop by 8.6% in the current growing season compared with a year earlier, sugar-industry

group Unica said Tuesday.

  The region, which produces about 90% of Brazil's cane, will produce 545.9 million metric tons of

the crop in the current 2014-2015 season, compared with 597.1 million tons in the 2013-2014 season.

Unica and Brazil's Cane Technology Center had earlier forecast a crop of 580 million tons for

2014-2015.

  Brazil is the world's biggest sugar producer and exporter, and the decline in output of the

sweetener has boosted prices on world markets.

  In the early part of the harvesting season, the drier-than-normal weather made it easier for farm

equipment to enter fields and helped accelerate the harvest and boost sugar and ethanol output above

normal levels.

  With much of the crop now harvested, mills are starting to crush less than they did a year earlier

and the season is expected to finish earlier than normal.

  "Traditional cane regions have been severely affected by the drought, and that should lead to an

earlier end to the  harvest and impede the harvest in areas where the plants didn't develop enough

to be cut," explained Unica's technical director, Antonio de Padua Rodrigues.

  Mills in the center-south region crushed 44.9 million tons of cane in the first half of August, a

decline of 3.4% from the same period a year earlier. Sugar output fell 4.3% in the first half of the

month from a year earlier, to 2.8 million tons, while ethanol production rose 4.4% in the same

period to 2.04 billion liters.

  The production mix of sugar and ethanol in the first half of the month was 45.7% sugar and 54.3%

ethanol, compared with 47.9% sugar and 52.1% ethanol a year earlier.

  Mills in the center-south crushed 325.3 million tons in the cane-growing season through Aug. 15,

an increase of 2.8% from the same period a year earlier. Sugar output rose 6.4% in the period to

17.9 million tons and ethanol production rose 4.5% to 13.9 billion liters.

  The production mix for the season through Aug. 15 was 44.2% sugar and 55.8% ethanol, compared with

43.7% sugar and 56.3% ethanol a year earlier.

 A rede de fast food Burger King anunciou nesta

terça-feira (26) a fusão com a companhia canadense de cafés, Tim Horton,

segundo o jornal "Wall Street Journal".

Com a aquisição, as duas companhias passam a formar a terceira maior cadeia de

fast food do mundo, com 18 mil lojas em mais de cem países.

O Burger King é controlado pelo fundo 3G, dos brasileiros Jorge Paulo Lemann,

Beto Sicupira e Marcel Telles, que já haviam se unido para a compra da Heinz,

em outubro de 2013.

A operação foi realizada com ajuda do megainvestidor Warren Buffett, que

financiou parte do negócio por meio da sua holding, o Berkshire Hathaway, O

empresário financiará 25% da compra, estimada em US$ 10 bilhões, em troca de

ações preferenciais, que têm maior liquidez e não dão direito ao voto nas

assembleias de acionistas.

De acordo com a publicação, a fusão do Burger King tem como principal objetivo

a redução de impostos. Com o acordo com a Tim Horton, a rede de lanchonetes

terá sinal verde para criar uma holding com sede no Canadá, onde a tributação é

menor.

A tendência já foi criticada pelo presidente Barack Obama e por assessores da

Casa Branca, que prometeram medidas do governo para reduzir a prática, que

afeta os cofres americanos.

Desde 1998, cerca de 40 companhias de diferentes setores fizeram aquisições

planejadas, mudando a sede das empresas para obter vantagens tributárias.

Dados da consultoria e auditoria KPMG mostram que o imposto sobre as empresas

canadenses é de 26,5%, enquanto nos EUA é de 40%.

Segundo o "Wall Street Journal", o presidente executivo do Burger King, Alex

Behring, irá liderar a nova companhia de atuação global, acumulando este cargo

e a função de diretor. Marc Caira, presidente do Tim Horton, será indicado à

vice-presidência e à diretoria da nova empresa.

Já Daniel Schwartz, CEO do Burger King, irá comandar a companhia resultante da

fusão neste mesmo cargo.

Três especialistas respondem sobre fisiologia cafeeira quando retornarem as chuvas.

Perguntei a 3 especialistas sobre o fragilidade dos estômatos para abrir e fechar corretamente e permanecer fechado depois de grave calor  e estresse hídrico.

Penso que mesmo com o retorno das chuvas , o cafeeiro arabica  não vai ser capaz de transpirar corretamente para reidratar-se .

Pois o problema não é só a obter a água e umidade para as raízes, mas as árvores terem capacidade de utilizar esta umidade.

Isto fará com que haja um desfolhamento excessivo e muitos frutos abortarem.

Meus agradecimentos aos Prof. Rena , Prof. Donizeti e Eng. Flavio Gassen , por imediatamente dividirem  os seus  conhecimentos com a comunidade cafeeira.

Prof. Alemar Braga Rena

Os resultados a seguir foram obtidos com mudas de 10 meses de idade, em sacolinhas com 800 ml de solo, mantidas durante o período experimental sob condições controladas de temperatura (25 C) e irradiância baixa (ca 500 micro-einsteins, por metro quadrado, por segundo, ou seja, aproximadamente 25% da luz solar máxima obtida nas condições de campo), mas o suficiente parar saturar a demanda fotossintética por luz, nas condições experimentais. Foram comparadas as reações de grupos de plantas permanentemente irrigados (controle) e grupos aos quais foi suspensa a irrigação, até que os potenciais hídricos foliares desejados eram alcançados.

Nestas condições ambientais, os seguintes resultados foram obtidos (Osmar Rodrigues e Alemar B. Rena, 1988):

Quando as folhas de Catuaí alcançaram déficits hídricos fortíssimos de -3,5 Mpa em cerca de 10 dias, a turgescência das folhas e a maquinaria fotossintética recuperaram-se em 24 h após o retorno da irrigação, mas o funcionamento dos estômatos, ou seja, a resistência estomática, somente se recuperou completamente nas próximas 72 h. Portanto, tudo voltou ao normal em 3 dias nas condições deste estudo. Mas algumas folhas sofreram a abscisão, ou seja, caíram.

No Mundo Novo, porém, a turgescência recuperou-se em 24 h, mas não a fotossíntese e a abertura estomática, que ficaram permanentemente prejudicadas, digamos, retornaram a apenas uns 20% da eficiência dos controles em duas semanas, mas nunca plenamente, até a queda das folhas. Há ainda que considerar que o Muno Novo  perde muitíssimo mais folhas do que o Catuaí, podendo ficar envaretado.

Entretanto, nas condições de campo a que foram submetidos os cafeeiros em 2014, de altíssimas irradiâncias e temperaturas, as folhas que permaneceram nas plantas jamais retornarão ao que eram após a recuperação da turgescência, que será rápida com a chuva (2 a 3 dias), possivelmente em todos os cultivares de café disponíveis no Brasil.

Se se considerar a morte de raízes pelo déficit hídrico e os danos mecânicos ao sistema radicular pelo descolamento do solo, o quadro pode ser muito mais sério para os cafeeiros desidratados de 2014. Enfim, como eu já afirmei muitas vezes, as plantas poderão não ser mais as mesmas por um bom tempo, digamos meses ou anos, podendo respingar em 2016.

Professor Jose Donizeti Alves

Os estômatos possuem movimento de abertura e fechamento em respostas ao ambiente. Basicamente luz, água, temperatura, CO2 e o hormônio (ABA) regulam esse processo.

Estômatos abertos permite a planta se reidratar, abaixar a temperatura foliar e ao mesmo tempo, absorver CO2 que será transformado em carboidrato pela fotossíntese.

Para que o processo de abertura e fechamento estomático ocorra normalmente é preciso que as células-guardas (células estomáticas) tenham a membrana plasmática intacta e,portanto, funcional.

Seca e alta temperatura por longo período de tempo promove a ruptura da membrana plasmática e a células-guardas se desestruturam e perdem a capacidade de se movimentar.

Com isso os estômatos podem permanecer fechados ou abertos indefinidamente. Se fechados tem-se: murcha das folhas, aumento da temperatura foliar, paralisação da fotossíntese e de todo processo metabólico como um todo que, ao se permanecer nessas condições por muito tempo (poucos dias), culminará com a queda das folhas.

Se permanecerem abertos, a folha irá se desidratar rapidamente, a temperatura foliar ira aumentar drasticamente paralisando todo o processo metabólico e queda de folhas.

Em nossa opinião, o fenômeno de desestruturação da membrana plasmática das células-guardas já esta acontecendo devido a seca e alta temperatura prolongada.

Eng. Flavio Glassen

Os danos citados referentes ao sistema radicular somente representam a parte inicial do sistema hídrico nos vegetais. O stress contínuo das plantas promove a má formação do sistema vascular e sua porção final que são os estômatos e hidatódios. Os pesquisadores Rena e Donizeti abordam muito bem este assunto. Tenho como hábito sempre trazer comigo um clorofilômetro manual (por absorbância) que apresenta o índice verde das folhas, tornando-se útil quando temos a referência numérica de uma folha saudável que varia conforme a genética. As folhas que estão em processo de abcisão por déficit hídrico apresentam redução uniforme no índice verde (diferente dos sintomas nutricionais), partindo da sua posição proximal e direcionando-se à distal (extremidade dos ramos). No momento que as folhas apresentam redução no índice verde por déficit hídrico, os estômatos já estavam comprometidos.  É possível criar um algoritmo para estimar o tempo necessário para que ocorra a abcisão de uma folha (queda), considerando o teor de umidade do solo atual, prognóstico da alteração desta umidade nos próximos dias e a diferença do Índice Verde das folhas atuais relativas ao índice referência. Uma vez deflagrado, o processo de abcisão é irreversível.  A agricultura é um grande canteiro de obras a realizar e este indicador é mais um a ser elaborado.  

Com certeza absoluta, a somatória temporal com déficit hídrico desde janeiro comprometeu a produção de fotoassimilados e o acúmulo de reservas que é significativamente inferior aos anos anteriores. Não há como compensar este tempo perdido com precipitação acima do normal à frente. Se isto ocorrer, cada ponto acima de 80% da capacidade de campo do solo (é necessário ajustar conforme origem do solo), será prejudicial. Por outro lado, não há evidência de precipitação acima do normal para o próximo verão na região sudeste, somente para a região sul do Brasil, Argentina e Uruguai.