I created a Vf page to show Account lookup and Picklist option. When An account is choosen the Picklist will render the values. 

Once I select the picklist value it is refreshing the entire VF page and showing the errors automatically for required fields if it is empty.

How to stop this can anyone please help me ?

**Page :**

    <apex:pageblocksection>
    <apex:actionRegion>
    
    	<span> Account </span>
    	<apex:inputField value="{!object__c.AccountId}">
    		<apex:actionSupport event="onchange" action="{!method1}"
    			rerender="op1">
    			<apex:param assignTo="{!acclookup}" value="{!object__c.AccountId}" />
    		</apex:actionSupport>
    
    	</apex:inputField>
    </apex:actionRegion>
    
    <apex:OutputPanel Id="op1">
                     Picklist
                        <apex:selectList value="{!pick}" multiselect="false"
    		size="1">
    		<apex:selectOptions value="{!options}" />
    		<apex:actionsupport event="onchange">
    			<apex:param assignTo="{!object__c.Picklist__C}" value="{!pick}" />
    		</apex:actionsupport>
    	</apex:selectList>
    </apex:OutputPanel>
    
    </apex:pageblocksection>